Commit 4dfce79e authored by Ville Syrjälä's avatar Ville Syrjälä Committed by Joonas Lahtinen
Browse files

drm/i915/dsi: Don't do DSC horizontal timing adjustments in command mode 

Stop adjusting the horizontal timing values based on the
compression ratio in command mode. Bspec seems to be telling
us to do this only in video mode, and this is also how the
Windows driver does things.

This should also fix a div-by-zero on some machines because
the adjusted htotal ends up being so small that we end up with
line_time_us==0 when trying to determine the vtotal value in
command mode.

Note that this doesn't actually make the display on the
Huawei Matebook E work, but at least the kernel no longer
explodes when the driver loads.

Cc: stable@vger.kernel.org
Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/12045


Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260326111814.9800-2-ville.syrjala@linux.intel.com


Fixes: 53693f02 ("drm/i915/dsi: account for DSC in horizontal timings")
Reviewed-by: default avatarJani Nikula <jani.nikula@intel.com>
(cherry picked from commit 0b475e91)
Signed-off-by: default avatarJoonas Lahtinen <joonas.lahtinen@linux.intel.com>
parent 7aaa8047

drivers/gpu/drm/i915/display/icl_dsi.c

+2 −2
Original line number Diff line number Diff line
@@ -889,7 +889,7 @@ gen11_dsi_set_transcoder_timings(struct intel_encoder *encoder, 
	 * non-compressed link speeds, and simplifies down to the ratio between

	 * compressed and non-compressed bpp.

	 */

	if (crtc_state->dsc.compression_enable) {

	if (is_vid_mode(intel_dsi) && crtc_state->dsc.compression_enable) {

		mul = fxp_q4_to_int(crtc_state->dsc.compressed_bpp_x16);

		div = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);

	}
@@ -1503,7 +1503,7 @@ static void gen11_dsi_get_timings(struct intel_encoder *encoder, 
	struct drm_display_mode *adjusted_mode =

					&pipe_config->hw.adjusted_mode;



	if (pipe_config->dsc.compressed_bpp_x16) {

	if (is_vid_mode(intel_dsi) && pipe_config->dsc.compressed_bpp_x16) {

		int div = fxp_q4_to_int(pipe_config->dsc.compressed_bpp_x16);

		int mul = mipi_dsi_pixel_format_to_bpp(intel_dsi->pixel_format);