-----Original Message----- From: Intel-gfx intel-gfx-bounces@lists.freedesktop.org On Behalf Of Ville Syrjala Sent: Wednesday, July 10, 2024 6:12 PM To: intel-gfx@lists.freedesktop.org Cc: stable@vger.kernel.org Subject: [PATCH] drm/i915: Fix readout degamma_lut mismatch on ilk/snb

From: Ville Syrjälä ville.syrjala@linux.intel.com

On ilk/snb the pipe may be configured to place the LUT before or after the CSC depending on various factors, but as there is only one LUT (no split mode like on IVB+) we only advertise a gamma_lut and no degamma_lut in the uapi to avoid confusing userspace.

This can cause a problem during readout if the VBIOS/GOP enabled the LUT in the pre CSC configuration. The current code blindly assigns the results of the readout to the degamma_lut, which will cause a failure during the next atomic_check() as we aren't expecting anything to be in degamma_lut since it's not visible to userspace.

Fix the problem by assigning whatever LUT we read out from the hardware into gamma_lut.

Looks Good to me. Reviewed-by: Uma Shankar uma.shankar@intel.com

Cc: stable@vger.kernel.org Fixes: d2559299d339 ("drm/i915: Make ilk_read_luts() capable of degamma readout") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11608 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com

---

.../drm/i915/display/intel_modeset_setup.c | 31 ++++++++++++++++--- 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_modeset_setup.c b/drivers/gpu/drm/i915/display/intel_modeset_setup.c index 7602cb30ebf1..e1213f3d93cc 100644 --- a/drivers/gpu/drm/i915/display/intel_modeset_setup.c +++ b/drivers/gpu/drm/i915/display/intel_modeset_setup.c @@ -326,6 +326,8 @@ static void intel_modeset_update_connector_atomic_state(struct drm_i915_private

static void intel_crtc_copy_hw_to_uapi_state(struct intel_crtc_state *crtc_state) {

• struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
• if (intel_crtc_is_joiner_secondary(crtc_state)) return;

@@ -337,11 +339,30 @@ static void intel_crtc_copy_hw_to_uapi_state(struct intel_crtc_state *crtc_state crtc_state->uapi.adjusted_mode = crtc_state->hw.adjusted_mode; crtc_state->uapi.scaling_filter = crtc_state->hw.scaling_filter;

• /* assume 1:1 mapping */
• drm_property_replace_blob(&crtc_state->hw.degamma_lut,

• 		  crtc_state->pre_csc_lut);
  

• drm_property_replace_blob(&crtc_state->hw.gamma_lut,

• 		  crtc_state->post_csc_lut);
  

• if (DISPLAY_INFO(i915)->color.degamma_lut_size) {

• /* assume 1:1 mapping */
  

• drm_property_replace_blob(&crtc_state->hw.degamma_lut,
  

• 			  crtc_state->pre_csc_lut);
  

• drm_property_replace_blob(&crtc_state->hw.gamma_lut,
  

• 			  crtc_state->post_csc_lut);
  

• } else {

• /*
  

•  * ilk/snb hw may be configured for either pre_csc_lut
  

•  * or post_csc_lut, but we don't advertise degamma_lut as
  

•  * being available in the uapi since there is only one
  

•  * hardware LUT. Always assign the result of the readout
  

•  * to gamma_lut as that is the only valid source of LUTs
  

•  * in the uapi.
  

•  */
  

• drm_WARN_ON(&i915->drm, crtc_state->post_csc_lut &&
  

• 	    crtc_state->pre_csc_lut);
  

• drm_property_replace_blob(&crtc_state->hw.degamma_lut,
  

• 			  NULL);
  

• drm_property_replace_blob(&crtc_state->hw.gamma_lut,
  

• 			  crtc_state->post_csc_lut ?:
  

• 			  crtc_state->pre_csc_lut);
  

• }

  drm_property_replace_blob(&crtc_state->uapi.degamma_lut, crtc_state->hw.degamma_lut);

-- 2.44.2