xref: /src/sys/external/bsd/drm2/dist/drm/i915/display/intel_crt.c

/*	$NetBSD: intel_crt.c,v 1.2 2021/12/18 23:45:29 riastradh Exp $	*/

/*
 * Copyright  2006-2007 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *	Eric Anholt <eric (at) anholt.net>
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: intel_crt.c,v 1.2 2021/12/18 23:45:29 riastradh Exp $");

#include <linux/dmi.h>
#include <linux/i2c.h>
#include <linux/slab.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drm_edid.h>
#include <drm/drm_probe_helper.h>
#include <drm/i915_drm.h>

#include "i915_drv.h"
#include "intel_connector.h"
#include "intel_crt.h"
#include "intel_ddi.h"
#include "intel_display_types.h"
#include "intel_fifo_underrun.h"
#include "intel_gmbus.h"
#include "intel_hotplug.h"

/* Here's the desired hotplug mode */
#define ADPA_HOTPLUG_BITS (ADPA_CRT_HOTPLUG_PERIOD_128 |		\
			   ADPA_CRT_HOTPLUG_WARMUP_10MS |		\
			   ADPA_CRT_HOTPLUG_SAMPLE_4S |			\
			   ADPA_CRT_HOTPLUG_VOLTAGE_50 |		\
			   ADPA_CRT_HOTPLUG_VOLREF_325MV |		\
			   ADPA_CRT_HOTPLUG_ENABLE)

struct intel_crt {
	struct intel_encoder base;
	/* DPMS state is stored in the connector, which we need in the
	 * encoder's enable/disable callbacks */
	struct intel_connector *connector;
	bool force_hotplug_required;
	i915_reg_t adpa_reg;
};

static struct intel_crt *intel_encoder_to_crt(struct intel_encoder *encoder)
{
	return container_of(encoder, struct intel_crt, base);
}

static struct intel_crt *intel_attached_crt(struct intel_connector *connector)
{
	return intel_encoder_to_crt(intel_attached_encoder(connector));
}

bool intel_crt_port_enabled(struct drm_i915_private *dev_priv,
			    i915_reg_t adpa_reg, enum pipe *pipe)
{
	u32 val;

	val = I915_READ(adpa_reg);

	/* asserts want to know the pipe even if the port is disabled */
	if (HAS_PCH_CPT(dev_priv))
		*pipe = (val & ADPA_PIPE_SEL_MASK_CPT) >> ADPA_PIPE_SEL_SHIFT_CPT;
	else
		*pipe = (val & ADPA_PIPE_SEL_MASK) >> ADPA_PIPE_SEL_SHIFT;

	return val & ADPA_DAC_ENABLE;
}

static bool intel_crt_get_hw_state(struct intel_encoder *encoder,
				   enum pipe *pipe)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct intel_crt *crt = intel_encoder_to_crt(encoder);
	intel_wakeref_t wakeref;
	bool ret;

	wakeref = intel_display_power_get_if_enabled(dev_priv,
						     encoder->power_domain);
	if (!wakeref)
		return false;

	ret = intel_crt_port_enabled(dev_priv, crt->adpa_reg, pipe);

	intel_display_power_put(dev_priv, encoder->power_domain, wakeref);

	return ret;
}

static unsigned int intel_crt_get_flags(struct intel_encoder *encoder)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct intel_crt *crt = intel_encoder_to_crt(encoder);
	u32 tmp, flags = 0;

	tmp = I915_READ(crt->adpa_reg);

	if (tmp & ADPA_HSYNC_ACTIVE_HIGH)
		flags |= DRM_MODE_FLAG_PHSYNC;
	else
		flags |= DRM_MODE_FLAG_NHSYNC;

	if (tmp & ADPA_VSYNC_ACTIVE_HIGH)
		flags |= DRM_MODE_FLAG_PVSYNC;
	else
		flags |= DRM_MODE_FLAG_NVSYNC;

	return flags;
}

static void intel_crt_get_config(struct intel_encoder *encoder,
				 struct intel_crtc_state *pipe_config)
{
	pipe_config->output_types |= BIT(INTEL_OUTPUT_ANALOG);

	pipe_config->hw.adjusted_mode.flags |= intel_crt_get_flags(encoder);

	pipe_config->hw.adjusted_mode.crtc_clock = pipe_config->port_clock;
}

static void hsw_crt_get_config(struct intel_encoder *encoder,
			       struct intel_crtc_state *pipe_config)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);

	intel_ddi_get_config(encoder, pipe_config);

	pipe_config->hw.adjusted_mode.flags &= ~(DRM_MODE_FLAG_PHSYNC |
					      DRM_MODE_FLAG_NHSYNC |
					      DRM_MODE_FLAG_PVSYNC |
					      DRM_MODE_FLAG_NVSYNC);
	pipe_config->hw.adjusted_mode.flags |= intel_crt_get_flags(encoder);

	pipe_config->hw.adjusted_mode.crtc_clock = lpt_get_iclkip(dev_priv);
}

/* Note: The caller is required to filter out dpms modes not supported by the
 * platform. */
static void intel_crt_set_dpms(struct intel_encoder *encoder,
			       const struct intel_crtc_state *crtc_state,
			       int mode)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct intel_crt *crt = intel_encoder_to_crt(encoder);
	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
	const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
	u32 adpa;

	if (INTEL_GEN(dev_priv) >= 5)
		adpa = ADPA_HOTPLUG_BITS;
	else
		adpa = 0;

	if (adjusted_mode->flags & DRM_MODE_FLAG_PHSYNC)
		adpa |= ADPA_HSYNC_ACTIVE_HIGH;
	if (adjusted_mode->flags & DRM_MODE_FLAG_PVSYNC)
		adpa |= ADPA_VSYNC_ACTIVE_HIGH;

	/* For CPT allow 3 pipe config, for others just use A or B */
	if (HAS_PCH_LPT(dev_priv))
		; /* Those bits don't exist here */
	else if (HAS_PCH_CPT(dev_priv))
		adpa |= ADPA_PIPE_SEL_CPT(crtc->pipe);
	else
		adpa |= ADPA_PIPE_SEL(crtc->pipe);

	if (!HAS_PCH_SPLIT(dev_priv))
		I915_WRITE(BCLRPAT(crtc->pipe), 0);

	switch (mode) {
	case DRM_MODE_DPMS_ON:
		adpa |= ADPA_DAC_ENABLE;
		break;
	case DRM_MODE_DPMS_STANDBY:
		adpa |= ADPA_DAC_ENABLE | ADPA_HSYNC_CNTL_DISABLE;
		break;
	case DRM_MODE_DPMS_SUSPEND:
		adpa |= ADPA_DAC_ENABLE | ADPA_VSYNC_CNTL_DISABLE;
		break;
	case DRM_MODE_DPMS_OFF:
		adpa |= ADPA_HSYNC_CNTL_DISABLE | ADPA_VSYNC_CNTL_DISABLE;
		break;
	}

	I915_WRITE(crt->adpa_reg, adpa);
}

static void intel_disable_crt(struct intel_encoder *encoder,
			      const struct intel_crtc_state *old_crtc_state,
			      const struct drm_connector_state *old_conn_state)
{
	intel_crt_set_dpms(encoder, old_crtc_state, DRM_MODE_DPMS_OFF);
}

static void pch_disable_crt(struct intel_encoder *encoder,
			    const struct intel_crtc_state *old_crtc_state,
			    const struct drm_connector_state *old_conn_state)
{
}

static void pch_post_disable_crt(struct intel_encoder *encoder,
				 const struct intel_crtc_state *old_crtc_state,
				 const struct drm_connector_state *old_conn_state)
{
	intel_disable_crt(encoder, old_crtc_state, old_conn_state);
}

static void hsw_disable_crt(struct intel_encoder *encoder,
			    const struct intel_crtc_state *old_crtc_state,
			    const struct drm_connector_state *old_conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);

	WARN_ON(!old_crtc_state->has_pch_encoder);

	intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
}

static void hsw_post_disable_crt(struct intel_encoder *encoder,
				 const struct intel_crtc_state *old_crtc_state,
				 const struct drm_connector_state *old_conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);

	intel_crtc_vblank_off(old_crtc_state);

	intel_disable_pipe(old_crtc_state);

	intel_ddi_disable_transcoder_func(old_crtc_state);

	ilk_pfit_disable(old_crtc_state);

	intel_ddi_disable_pipe_clock(old_crtc_state);

	pch_post_disable_crt(encoder, old_crtc_state, old_conn_state);

	lpt_disable_pch_transcoder(dev_priv);
	lpt_disable_iclkip(dev_priv);

	intel_ddi_fdi_post_disable(encoder, old_crtc_state, old_conn_state);

	WARN_ON(!old_crtc_state->has_pch_encoder);

	intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
}

static void hsw_pre_pll_enable_crt(struct intel_encoder *encoder,
				   const struct intel_crtc_state *crtc_state,
				   const struct drm_connector_state *conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);

	WARN_ON(!crtc_state->has_pch_encoder);

	intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, false);
}

static void hsw_pre_enable_crt(struct intel_encoder *encoder,
			       const struct intel_crtc_state *crtc_state,
			       const struct drm_connector_state *conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
	enum pipe pipe = crtc->pipe;

	WARN_ON(!crtc_state->has_pch_encoder);

	intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, false);

	hsw_fdi_link_train(encoder, crtc_state);

	intel_ddi_enable_pipe_clock(crtc_state);
}

static void hsw_enable_crt(struct intel_encoder *encoder,
			   const struct intel_crtc_state *crtc_state,
			   const struct drm_connector_state *conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
	enum pipe pipe = crtc->pipe;

	WARN_ON(!crtc_state->has_pch_encoder);

	intel_crt_set_dpms(encoder, crtc_state, DRM_MODE_DPMS_ON);

	intel_wait_for_vblank(dev_priv, pipe);
	intel_wait_for_vblank(dev_priv, pipe);
	intel_set_cpu_fifo_underrun_reporting(dev_priv, pipe, true);
	intel_set_pch_fifo_underrun_reporting(dev_priv, PIPE_A, true);
}

static void intel_enable_crt(struct intel_encoder *encoder,
			     const struct intel_crtc_state *crtc_state,
			     const struct drm_connector_state *conn_state)
{
	intel_crt_set_dpms(encoder, crtc_state, DRM_MODE_DPMS_ON);
}

static enum drm_mode_status
intel_crt_mode_valid(struct drm_connector *connector,
		     struct drm_display_mode *mode)
{
	struct drm_device *dev = connector->dev;
	struct drm_i915_private *dev_priv = to_i915(dev);
	int max_dotclk = dev_priv->max_dotclk_freq;
	int max_clock;

	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
		return MODE_NO_DBLESCAN;

	if (mode->clock < 25000)
		return MODE_CLOCK_LOW;

	if (HAS_PCH_LPT(dev_priv))
		max_clock = 180000;
	else if (IS_VALLEYVIEW(dev_priv))
		/*
		 * 270 MHz due to current DPLL limits,
		 * DAC limit supposedly 355 MHz.
		 */
		max_clock = 270000;
	else if (IS_GEN_RANGE(dev_priv, 3, 4))
		max_clock = 400000;
	else
		max_clock = 350000;
	if (mode->clock > max_clock)
		return MODE_CLOCK_HIGH;

	if (mode->clock > max_dotclk)
		return MODE_CLOCK_HIGH;

	/* The FDI receiver on LPT only supports 8bpc and only has 2 lanes. */
	if (HAS_PCH_LPT(dev_priv) &&
	    ilk_get_lanes_required(mode->clock, 270000, 24) > 2)
		return MODE_CLOCK_HIGH;

	/* HSW/BDW FDI limited to 4k */
	if (mode->hdisplay > 4096)
		return MODE_H_ILLEGAL;

	return MODE_OK;
}

static int intel_crt_compute_config(struct intel_encoder *encoder,
				    struct intel_crtc_state *pipe_config,
				    struct drm_connector_state *conn_state)
{
	struct drm_display_mode *adjusted_mode =
		&pipe_config->hw.adjusted_mode;

	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
		return -EINVAL;

	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;

	return 0;
}

static int pch_crt_compute_config(struct intel_encoder *encoder,
				  struct intel_crtc_state *pipe_config,
				  struct drm_connector_state *conn_state)
{
	struct drm_display_mode *adjusted_mode =
		&pipe_config->hw.adjusted_mode;

	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
		return -EINVAL;

	pipe_config->has_pch_encoder = true;
	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;

	return 0;
}

static int hsw_crt_compute_config(struct intel_encoder *encoder,
				  struct intel_crtc_state *pipe_config,
				  struct drm_connector_state *conn_state)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
	struct drm_display_mode *adjusted_mode =
		&pipe_config->hw.adjusted_mode;

	if (adjusted_mode->flags & DRM_MODE_FLAG_DBLSCAN)
		return -EINVAL;

	/* HSW/BDW FDI limited to 4k */
	if (adjusted_mode->crtc_hdisplay > 4096 ||
	    adjusted_mode->crtc_hblank_start > 4096)
		return -EINVAL;

	pipe_config->has_pch_encoder = true;
	pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;

	/* LPT FDI RX only supports 8bpc. */
	if (HAS_PCH_LPT(dev_priv)) {
		if (pipe_config->bw_constrained && pipe_config->pipe_bpp < 24) {
			DRM_DEBUG_KMS("LPT only supports 24bpp\n");
			return -EINVAL;
		}

		pipe_config->pipe_bpp = 24;
	}

	/* FDI must always be 2.7 GHz */
	pipe_config->port_clock = 135000 * 2;

	return 0;
}

static bool ilk_crt_detect_hotplug(struct drm_connector *connector)
{
	struct drm_device *dev = connector->dev;
	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
	struct drm_i915_private *dev_priv = to_i915(dev);
	u32 adpa;
	bool ret;

	/* The first time through, trigger an explicit detection cycle */
	if (crt->force_hotplug_required) {
		bool turn_off_dac = HAS_PCH_SPLIT(dev_priv);
		u32 save_adpa;

		crt->force_hotplug_required = false;

		save_adpa = adpa = I915_READ(crt->adpa_reg);
		DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);

		adpa |= ADPA_CRT_HOTPLUG_FORCE_TRIGGER;
		if (turn_off_dac)
			adpa &= ~ADPA_DAC_ENABLE;

		I915_WRITE(crt->adpa_reg, adpa);

		if (intel_de_wait_for_clear(dev_priv,
					    crt->adpa_reg,
					    ADPA_CRT_HOTPLUG_FORCE_TRIGGER,
					    1000))
			DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");

		if (turn_off_dac) {
			I915_WRITE(crt->adpa_reg, save_adpa);
			POSTING_READ(crt->adpa_reg);
		}
	}

	/* Check the status to see if both blue and green are on now */
	adpa = I915_READ(crt->adpa_reg);
	if ((adpa & ADPA_CRT_HOTPLUG_MONITOR_MASK) != 0)
		ret = true;
	else
		ret = false;
	DRM_DEBUG_KMS("ironlake hotplug adpa=0x%x, result %d\n", adpa, ret);

	return ret;
}

static bool valleyview_crt_detect_hotplug(struct drm_connector *connector)
{
	struct drm_device *dev = connector->dev;
	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
	struct drm_i915_private *dev_priv = to_i915(dev);
	bool reenable_hpd;
	u32 adpa;
	bool ret;
	u32 save_adpa;

	/*
	 * Doing a force trigger causes a hpd interrupt to get sent, which can
	 * get us stuck in a loop if we're polling:
	 *  - We enable power wells and reset the ADPA
	 *  - output_poll_exec does force probe on VGA, triggering a hpd
	 *  - HPD handler waits for poll to unlock dev->mode_config.mutex
	 *  - output_poll_exec shuts off the ADPA, unlocks
	 *    dev->mode_config.mutex
	 *  - HPD handler runs, resets ADPA and brings us back to the start
	 *
	 * Just disable HPD interrupts here to prevent this
	 */
	reenable_hpd = intel_hpd_disable(dev_priv, crt->base.hpd_pin);

	save_adpa = adpa = I915_READ(crt->adpa_reg);
	DRM_DEBUG_KMS("trigger hotplug detect cycle: adpa=0x%x\n", adpa);

	adpa |= ADPA_CRT_HOTPLUG_FORCE_TRIGGER;

	I915_WRITE(crt->adpa_reg, adpa);

	if (intel_de_wait_for_clear(dev_priv, crt->adpa_reg,
				    ADPA_CRT_HOTPLUG_FORCE_TRIGGER, 1000)) {
		DRM_DEBUG_KMS("timed out waiting for FORCE_TRIGGER");
		I915_WRITE(crt->adpa_reg, save_adpa);
	}

	/* Check the status to see if both blue and green are on now */
	adpa = I915_READ(crt->adpa_reg);
	if ((adpa & ADPA_CRT_HOTPLUG_MONITOR_MASK) != 0)
		ret = true;
	else
		ret = false;

	DRM_DEBUG_KMS("valleyview hotplug adpa=0x%x, result %d\n", adpa, ret);

	if (reenable_hpd)
		intel_hpd_enable(dev_priv, crt->base.hpd_pin);

	return ret;
}

static bool intel_crt_detect_hotplug(struct drm_connector *connector)
{
	struct drm_device *dev = connector->dev;
	struct drm_i915_private *dev_priv = to_i915(dev);
	u32 stat;
	bool ret = false;
	int i, tries = 0;

	if (HAS_PCH_SPLIT(dev_priv))
		return ilk_crt_detect_hotplug(connector);

	if (IS_VALLEYVIEW(dev_priv))
		return valleyview_crt_detect_hotplug(connector);

	/*
	 * On 4 series desktop, CRT detect sequence need to be done twice
	 * to get a reliable result.
	 */

	if (IS_G45(dev_priv))
		tries = 2;
	else
		tries = 1;

	for (i = 0; i < tries ; i++) {
		/* turn on the FORCE_DETECT */
		i915_hotplug_interrupt_update(dev_priv,
					      CRT_HOTPLUG_FORCE_DETECT,
					      CRT_HOTPLUG_FORCE_DETECT);
		/* wait for FORCE_DETECT to go off */
		if (intel_de_wait_for_clear(dev_priv, PORT_HOTPLUG_EN,
					    CRT_HOTPLUG_FORCE_DETECT, 1000))
			DRM_DEBUG_KMS("timed out waiting for FORCE_DETECT to go off");
	}

	stat = I915_READ(PORT_HOTPLUG_STAT);
	if ((stat & CRT_HOTPLUG_MONITOR_MASK) != CRT_HOTPLUG_MONITOR_NONE)
		ret = true;

	/* clear the interrupt we just generated, if any */
	I915_WRITE(PORT_HOTPLUG_STAT, CRT_HOTPLUG_INT_STATUS);

	i915_hotplug_interrupt_update(dev_priv, CRT_HOTPLUG_FORCE_DETECT, 0);

	return ret;
}

static struct edid *intel_crt_get_edid(struct drm_connector *connector,
				struct i2c_adapter *i2c)
{
	struct edid *edid;

	edid = drm_get_edid(connector, i2c);

	if (!edid && !intel_gmbus_is_forced_bit(i2c)) {
		DRM_DEBUG_KMS("CRT GMBUS EDID read failed, retry using GPIO bit-banging\n");
		intel_gmbus_force_bit(i2c, true);
		edid = drm_get_edid(connector, i2c);
		intel_gmbus_force_bit(i2c, false);
	}

	return edid;
}

/* local version of intel_ddc_get_modes() to use intel_crt_get_edid() */
static int intel_crt_ddc_get_modes(struct drm_connector *connector,
				struct i2c_adapter *adapter)
{
	struct edid *edid;
	int ret;

	edid = intel_crt_get_edid(connector, adapter);
	if (!edid)
		return 0;

	ret = intel_connector_update_modes(connector, edid);
	kfree(edid);

	return ret;
}

static bool intel_crt_detect_ddc(struct drm_connector *connector)
{
	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
	struct drm_i915_private *dev_priv = to_i915(crt->base.base.dev);
	struct edid *edid;
	struct i2c_adapter *i2c;
	bool ret = false;

	BUG_ON(crt->base.type != INTEL_OUTPUT_ANALOG);

	i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->vbt.crt_ddc_pin);
	edid = intel_crt_get_edid(connector, i2c);

	if (edid) {
		bool is_digital = edid->input & DRM_EDID_INPUT_DIGITAL;

		/*
		 * This may be a DVI-I connector with a shared DDC
		 * link between analog and digital outputs, so we
		 * have to check the EDID input spec of the attached device.
		 */
		if (!is_digital) {
			DRM_DEBUG_KMS("CRT detected via DDC:0x50 [EDID]\n");
			ret = true;
		} else {
			DRM_DEBUG_KMS("CRT not detected via DDC:0x50 [EDID reports a digital panel]\n");
		}
	} else {
		DRM_DEBUG_KMS("CRT not detected via DDC:0x50 [no valid EDID found]\n");
	}

	kfree(edid);

	return ret;
}

static enum drm_connector_status
intel_crt_load_detect(struct intel_crt *crt, u32 pipe)
{
	struct drm_device *dev = crt->base.base.dev;
	struct drm_i915_private *dev_priv = to_i915(dev);
	struct intel_uncore *uncore = &dev_priv->uncore;
	u32 save_bclrpat;
	u32 save_vtotal;
	u32 vtotal, vactive;
	u32 vsample;
	u32 vblank, vblank_start, vblank_end;
	u32 dsl;
	i915_reg_t bclrpat_reg, vtotal_reg,
		vblank_reg, vsync_reg, pipeconf_reg, pipe_dsl_reg;
	u8 st00;
	enum drm_connector_status status;

	DRM_DEBUG_KMS("starting load-detect on CRT\n");

	bclrpat_reg = BCLRPAT(pipe);
	vtotal_reg = VTOTAL(pipe);
	vblank_reg = VBLANK(pipe);
	vsync_reg = VSYNC(pipe);
	pipeconf_reg = PIPECONF(pipe);
	pipe_dsl_reg = PIPEDSL(pipe);

	save_bclrpat = intel_uncore_read(uncore, bclrpat_reg);
	save_vtotal = intel_uncore_read(uncore, vtotal_reg);
	vblank = intel_uncore_read(uncore, vblank_reg);

	vtotal = ((save_vtotal >> 16) & 0xfff) + 1;
	vactive = (save_vtotal & 0x7ff) + 1;

	vblank_start = (vblank & 0xfff) + 1;
	vblank_end = ((vblank >> 16) & 0xfff) + 1;

	/* Set the border color to purple. */
	intel_uncore_write(uncore, bclrpat_reg, 0x500050);

	if (!IS_GEN(dev_priv, 2)) {
		u32 pipeconf = intel_uncore_read(uncore, pipeconf_reg);
		intel_uncore_write(uncore,
				   pipeconf_reg,
				   pipeconf | PIPECONF_FORCE_BORDER);
		intel_uncore_posting_read(uncore, pipeconf_reg);
		/* Wait for next Vblank to substitue
		 * border color for Color info */
		intel_wait_for_vblank(dev_priv, pipe);
		st00 = intel_uncore_read8(uncore, _VGA_MSR_WRITE);
		status = ((st00 & (1 << 4)) != 0) ?
			connector_status_connected :
			connector_status_disconnected;

		intel_uncore_write(uncore, pipeconf_reg, pipeconf);
	} else {
		bool restore_vblank = false;
		int count, detect;

		/*
		* If there isn't any border, add some.
		* Yes, this will flicker
		*/
		if (vblank_start <= vactive && vblank_end >= vtotal) {
			u32 vsync = I915_READ(vsync_reg);
			u32 vsync_start = (vsync & 0xffff) + 1;

			vblank_start = vsync_start;
			intel_uncore_write(uncore,
					   vblank_reg,
					   (vblank_start - 1) |
					   ((vblank_end - 1) << 16));
			restore_vblank = true;
		}
		/* sample in the vertical border, selecting the larger one */
		if (vblank_start - vactive >= vtotal - vblank_end)
			vsample = (vblank_start + vactive) >> 1;
		else
			vsample = (vtotal + vblank_end) >> 1;

		/*
		 * Wait for the border to be displayed
		 */
		while (intel_uncore_read(uncore, pipe_dsl_reg) >= vactive)
			;
		while ((dsl = intel_uncore_read(uncore, pipe_dsl_reg)) <=
		       vsample)
			;
		/*
		 * Watch ST00 for an entire scanline
		 */
		detect = 0;
		count = 0;
		do {
			count++;
			/* Read the ST00 VGA status register */
			st00 = intel_uncore_read8(uncore, _VGA_MSR_WRITE);
			if (st00 & (1 << 4))
				detect++;
		} while ((intel_uncore_read(uncore, pipe_dsl_reg) == dsl));

		/* restore vblank if necessary */
		if (restore_vblank)
			intel_uncore_write(uncore, vblank_reg, vblank);
		/*
		 * If more than 3/4 of the scanline detected a monitor,
		 * then it is assumed to be present. This works even on i830,
		 * where there isn't any way to force the border color across
		 * the screen
		 */
		status = detect * 4 > count * 3 ?
			 connector_status_connected :
			 connector_status_disconnected;
	}

	/* Restore previous settings */
	intel_uncore_write(uncore, bclrpat_reg, save_bclrpat);

	return status;
}

static int intel_spurious_crt_detect_dmi_callback(const struct dmi_system_id *id)
{
	DRM_DEBUG_DRIVER("Skipping CRT detection for %s\n", id->ident);
	return 1;
}

static const struct dmi_system_id intel_spurious_crt_detect[] = {
	{
		.callback = intel_spurious_crt_detect_dmi_callback,
		.ident = "ACER ZGB",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "ACER"),
			DMI_MATCH(DMI_PRODUCT_NAME, "ZGB"),
		},
	},
	{
		.callback = intel_spurious_crt_detect_dmi_callback,
		.ident = "Intel DZ77BH-55K",
		.matches = {
			DMI_MATCH(DMI_BOARD_VENDOR, "Intel Corporation"),
			DMI_MATCH(DMI_BOARD_NAME, "DZ77BH-55K"),
		},
	},
	{ }
};

static int
intel_crt_detect(struct drm_connector *connector,
		 struct drm_modeset_acquire_ctx *ctx,
		 bool force)
{
	struct drm_i915_private *dev_priv = to_i915(connector->dev);
	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
	struct intel_encoder *intel_encoder = &crt->base;
	intel_wakeref_t wakeref;
	int status, ret;
	struct intel_load_detect_pipe tmp;

	DRM_DEBUG_KMS("[CONNECTOR:%d:%s] force=%d\n",
		      connector->base.id, connector->name,
		      force);

	if (i915_modparams.load_detect_test) {
		wakeref = intel_display_power_get(dev_priv,
						  intel_encoder->power_domain);
		goto load_detect;
	}

	/* Skip machines without VGA that falsely report hotplug events */
	if (dmi_check_system(intel_spurious_crt_detect))
		return connector_status_disconnected;

	wakeref = intel_display_power_get(dev_priv,
					  intel_encoder->power_domain);

	if (I915_HAS_HOTPLUG(dev_priv)) {
		/* We can not rely on the HPD pin always being correctly wired
		 * up, for example many KVM do not pass it through, and so
		 * only trust an assertion that the monitor is connected.
		 */
		if (intel_crt_detect_hotplug(connector)) {
			DRM_DEBUG_KMS("CRT detected via hotplug\n");
			status = connector_status_connected;
			goto out;
		} else
			DRM_DEBUG_KMS("CRT not detected via hotplug\n");
	}

	if (intel_crt_detect_ddc(connector)) {
		status = connector_status_connected;
		goto out;
	}

	/* Load detection is broken on HPD capable machines. Whoever wants a
	 * broken monitor (without edid) to work behind a broken kvm (that fails
	 * to have the right resistors for HP detection) needs to fix this up.
	 * For now just bail out. */
	if (I915_HAS_HOTPLUG(dev_priv)) {
		status = connector_status_disconnected;
		goto out;
	}

load_detect:
	if (!force) {
		status = connector->status;
		goto out;
	}

	/* for pre-945g platforms use load detect */
	ret = intel_get_load_detect_pipe(connector, &tmp, ctx);
	if (ret > 0) {
		if (intel_crt_detect_ddc(connector))
			status = connector_status_connected;
		else if (INTEL_GEN(dev_priv) < 4)
			status = intel_crt_load_detect(crt,
				to_intel_crtc(connector->state->crtc)->pipe);
		else if (i915_modparams.load_detect_test)
			status = connector_status_disconnected;
		else
			status = connector_status_unknown;
		intel_release_load_detect_pipe(connector, &tmp, ctx);
	} else if (ret == 0) {
		status = connector_status_unknown;
	} else {
		status = ret;
	}

out:
	intel_display_power_put(dev_priv, intel_encoder->power_domain, wakeref);

	/*
	 * Make sure the refs for power wells enabled during detect are
	 * dropped to avoid a new detect cycle triggered by HPD polling.
	 */
	intel_display_power_flush_work(dev_priv);

	return status;
}

static int intel_crt_get_modes(struct drm_connector *connector)
{
	struct drm_device *dev = connector->dev;
	struct drm_i915_private *dev_priv = to_i915(dev);
	struct intel_crt *crt = intel_attached_crt(to_intel_connector(connector));
	struct intel_encoder *intel_encoder = &crt->base;
	intel_wakeref_t wakeref;
	struct i2c_adapter *i2c;
	int ret;

	wakeref = intel_display_power_get(dev_priv,
					  intel_encoder->power_domain);

	i2c = intel_gmbus_get_adapter(dev_priv, dev_priv->vbt.crt_ddc_pin);
	ret = intel_crt_ddc_get_modes(connector, i2c);
	if (ret || !IS_G4X(dev_priv))
		goto out;

	/* Try to probe digital port for output in DVI-I -> VGA mode. */
	i2c = intel_gmbus_get_adapter(dev_priv, GMBUS_PIN_DPB);
	ret = intel_crt_ddc_get_modes(connector, i2c);

out:
	intel_display_power_put(dev_priv, intel_encoder->power_domain, wakeref);

	return ret;
}

void intel_crt_reset(struct drm_encoder *encoder)
{
	struct drm_i915_private *dev_priv = to_i915(encoder->dev);
	struct intel_crt *crt = intel_encoder_to_crt(to_intel_encoder(encoder));

	if (INTEL_GEN(dev_priv) >= 5) {
		u32 adpa;

		adpa = I915_READ(crt->adpa_reg);
		adpa &= ~ADPA_CRT_HOTPLUG_MASK;
		adpa |= ADPA_HOTPLUG_BITS;
		I915_WRITE(crt->adpa_reg, adpa);
		POSTING_READ(crt->adpa_reg);

		DRM_DEBUG_KMS("crt adpa set to 0x%x\n", adpa);
		crt->force_hotplug_required = true;
	}

}

/*
 * Routines for controlling stuff on the analog port
 */

static const struct drm_connector_funcs intel_crt_connector_funcs = {
	.fill_modes = drm_helper_probe_single_connector_modes,
	.late_register = intel_connector_register,
	.early_unregister = intel_connector_unregister,
	.destroy = intel_connector_destroy,
	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
};

static const struct drm_connector_helper_funcs intel_crt_connector_helper_funcs = {
	.detect_ctx = intel_crt_detect,
	.mode_valid = intel_crt_mode_valid,
	.get_modes = intel_crt_get_modes,
};

static const struct drm_encoder_funcs intel_crt_enc_funcs = {
	.reset = intel_crt_reset,
	.destroy = intel_encoder_destroy,
};

void intel_crt_init(struct drm_i915_private *dev_priv)
{
	struct drm_connector *connector;
	struct intel_crt *crt;
	struct intel_connector *intel_connector;
	i915_reg_t adpa_reg;
	u32 adpa;

	if (HAS_PCH_SPLIT(dev_priv))
		adpa_reg = PCH_ADPA;
	else if (IS_VALLEYVIEW(dev_priv))
		adpa_reg = VLV_ADPA;
	else
		adpa_reg = ADPA;

	adpa = I915_READ(adpa_reg);
	if ((adpa & ADPA_DAC_ENABLE) == 0) {
		/*
		 * On some machines (some IVB at least) CRT can be
		 * fused off, but there's no known fuse bit to
		 * indicate that. On these machine the ADPA register
		 * works normally, except the DAC enable bit won't
		 * take. So the only way to tell is attempt to enable
		 * it and see what happens.
		 */
		I915_WRITE(adpa_reg, adpa | ADPA_DAC_ENABLE |
			   ADPA_HSYNC_CNTL_DISABLE | ADPA_VSYNC_CNTL_DISABLE);
		if ((I915_READ(adpa_reg) & ADPA_DAC_ENABLE) == 0)
			return;
		I915_WRITE(adpa_reg, adpa);
	}

	crt = kzalloc(sizeof(struct intel_crt), GFP_KERNEL);
	if (!crt)
		return;

	intel_connector = intel_connector_alloc();
	if (!intel_connector) {
		kfree(crt);
		return;
	}

	connector = &intel_connector->base;
	crt->connector = intel_connector;
	drm_connector_init(&dev_priv->drm, &intel_connector->base,
			   &intel_crt_connector_funcs, DRM_MODE_CONNECTOR_VGA);

	drm_encoder_init(&dev_priv->drm, &crt->base.base, &intel_crt_enc_funcs,
			 DRM_MODE_ENCODER_DAC, "CRT");

	intel_connector_attach_encoder(intel_connector, &crt->base);

	crt->base.type = INTEL_OUTPUT_ANALOG;
	crt->base.cloneable = (1 << INTEL_OUTPUT_DVO) | (1 << INTEL_OUTPUT_HDMI);
	if (IS_I830(dev_priv))
		crt->base.pipe_mask = BIT(PIPE_A);
	else
		crt->base.pipe_mask = ~0;

	if (IS_GEN(dev_priv, 2))
		connector->interlace_allowed = 0;
	else
		connector->interlace_allowed = 1;
	connector->doublescan_allowed = 0;

	crt->adpa_reg = adpa_reg;

	crt->base.power_domain = POWER_DOMAIN_PORT_CRT;

	if (I915_HAS_HOTPLUG(dev_priv) &&
	    !dmi_check_system(intel_spurious_crt_detect)) {
		crt->base.hpd_pin = HPD_CRT;
		crt->base.hotplug = intel_encoder_hotplug;
	}

	if (HAS_DDI(dev_priv)) {
		crt->base.port = PORT_E;
		crt->base.get_config = hsw_crt_get_config;
		crt->base.get_hw_state = intel_ddi_get_hw_state;
		crt->base.compute_config = hsw_crt_compute_config;
		crt->base.pre_pll_enable = hsw_pre_pll_enable_crt;
		crt->base.pre_enable = hsw_pre_enable_crt;
		crt->base.enable = hsw_enable_crt;
		crt->base.disable = hsw_disable_crt;
		crt->base.post_disable = hsw_post_disable_crt;
	} else {
		if (HAS_PCH_SPLIT(dev_priv)) {
			crt->base.compute_config = pch_crt_compute_config;
			crt->base.disable = pch_disable_crt;
			crt->base.post_disable = pch_post_disable_crt;
		} else {
			crt->base.compute_config = intel_crt_compute_config;
			crt->base.disable = intel_disable_crt;
		}
		crt->base.port = PORT_NONE;
		crt->base.get_config = intel_crt_get_config;
		crt->base.get_hw_state = intel_crt_get_hw_state;
		crt->base.enable = intel_enable_crt;
	}
	intel_connector->get_hw_state = intel_connector_get_hw_state;

	drm_connector_helper_add(connector, &intel_crt_connector_helper_funcs);

	if (!I915_HAS_HOTPLUG(dev_priv))
		intel_connector->polled = DRM_CONNECTOR_POLL_CONNECT;

	/*
	 * Configure the automatic hotplug detection stuff
	 */
	crt->force_hotplug_required = false;

	/*
	 * TODO: find a proper way to discover whether we need to set the the
	 * polarity and link reversal bits or not, instead of relying on the
	 * BIOS.
	 */
	if (HAS_PCH_LPT(dev_priv)) {
		u32 fdi_config = FDI_RX_POLARITY_REVERSED_LPT |
				 FDI_RX_LINK_REVERSAL_OVERRIDE;

		dev_priv->fdi_rx_config = I915_READ(FDI_RX_CTL(PIPE_A)) & fdi_config;
	}

	intel_crt_reset(&crt->base.base);
}