drm/i915: debugfs: Add support for probing DP sink CRC.

This debugfs interface will allow intel-gpu-tools test case
to verify if screen has been updated properly on cases like PSR.

v2: Accepted all Daniel's suggestions:
    * grab modeset lock
    * loop over connector and check DPMS on
    * return errors
    * use _eDP1 suffix for easy future extension
    * don't cache crc_supported neither latest crc
    * return crc as a full array and read it at once with aux.
    * use 0 to turn TEST_SINK off.
    * split the drm_helpers definitions in another patch.

v3: Accepted 2 Damien's suggestion: remove h from printf hexa
    and return ENODEV when eDP not present instead of EAGAIN.

v4: Accepted 2 Jani' s suggestion: 1 path for unlock and remove
    _retry from aux read.

v5: removing last missing useless _retry (by Damien)

Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@gmail.com>
Reviewed-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 29 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index e37c7a03753..389eabf898a 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -2922,6 +2922,35 @@ intel_dp_probe_oui(struct intel_dp *intel_dp)
 	edp_panel_vdd_off(intel_dp, false);
 }
 
+int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc)
+{
+	struct intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
+	struct drm_device *dev = intel_dig_port->base.base.dev;
+	struct intel_crtc *intel_crtc =
+		to_intel_crtc(intel_dig_port->base.base.crtc);
+	u8 buf[1];
+
+	if (!intel_dp_aux_native_read(intel_dp, DP_TEST_SINK_MISC, buf, 1))
+		return -EAGAIN;
+
+	if (!(buf[0] & DP_TEST_CRC_SUPPORTED))
+		return -ENOTTY;
+
+	if (!intel_dp_aux_native_write_1(intel_dp, DP_TEST_SINK,
+					 DP_TEST_SINK_START))
+		return -EAGAIN;
+
+	/* Wait 2 vblanks to be sure we will have the correct CRC value */
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
+	intel_wait_for_vblank(dev, intel_crtc->pipe);
+
+	if (!intel_dp_aux_native_read(intel_dp, DP_TEST_CRC_R_CR, crc, 6))
+		return -EAGAIN;
+
+	intel_dp_aux_native_write_1(intel_dp, DP_TEST_SINK, 0);
+	return 0;
+}
+
 static bool
 intel_dp_get_sink_irq(struct intel_dp *intel_dp, u8 *sink_irq_vector)
 {