kernel/drivers/gpu/drm/i915/display/intel_vrr.c, branch linux-rolling-stable

drm/i915/vrr: Configure VRR timings after enabling TRANS_DDI_FUNC_CTL

2026-03-19T15:15:24Z

commit 237aab549676288d9255bb8dcc284738e56eaa31 upstream. Apparently ICL may hang with an MCE if we write TRANS_VRR_VMAX/FLIPLINE before enabling TRANS_DDI_FUNC_CTL. Personally I was only able to reproduce a hang (on an Dell XPS 7390 2-in-1) with an external display connected via a dock using a dodgy type-C cable that made the link training fail. After the failed link training the machine would hang. TGL seemed immune to the problem for whatever reason. BSpec does tell us to configure VRR after enabling TRANS_DDI_FUNC_CTL as well. The DMC firmware also does the VRR restore in two stages: - first stage seems to be unconditional and includes TRANS_VRR_CTL and a few other VRR registers, among other things - second stage is conditional on the DDI being enabled, and includes TRANS_DDI_FUNC_CTL and TRANS_VRR_VMAX/VMIN/FLIPLINE, among other things So let's reorder the steps to match to avoid the hang, and toss in an extra WARN to make sure we don't screw this up later. BSpec: 22243 Cc: stable@vger.kernel.org Cc: Ankit Nautiyal Reported-by: Benjamin Tissoires Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/15777 Tested-by: Benjamin Tissoires Fixes: dda7dcd9da73 ("drm/i915/vrr: Use fixed timings for platforms that support VRR") Signed-off-by: Ville Syrjälä Link: https://patch.msgid.link/20260303095414.4331-1-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal (cherry picked from commit 93f3a267c3dd4d811b224bb9e179a10d81456a74) Signed-off-by: Tvrtko Ursulin Signed-off-by: Greg Kroah-Hartman

drm/i915/de: Include units in intel_de_wait*() function names

2025-11-11T17:27:46Z

intel_de_wait*() take the timeout in milliseconds. Include that information in the function name to make life less confusing. I'll also be introducing microsecond variants of these later. Done with cocci: @@ @@ ( static int - intel_de_wait + intel_de_wait_ms (...) { ... } | static int - intel_de_wait_fw + intel_de_wait_fw_ms (...) { ... } | static int - intel_de_wait_for_set + intel_de_wait_for_set_ms (...) { ... } | static int - intel_de_wait_for_clear + intel_de_wait_for_clear_ms (...) { ... } ) @@ @@ ( - intel_de_wait + intel_de_wait_ms | - intel_de_wait_fw + intel_de_wait_fw_ms | - intel_de_wait_for_set + intel_de_wait_for_set_ms | - intel_de_wait_for_clear + intel_de_wait_for_clear_ms ) Signed-off-by: Ville Syrjälä Link: https://patch.msgid.link/20251110172756.2132-4-ville.syrjala@linux.intel.com Reviewed-by: Suraj Kandpal Acked-by: Jani Nikula

drm/i915/vrr: Check HAS_VRR() first in intel_vrr_is_capable()

2025-10-24T21:10:58Z

There's no point in doing all the other checks in intel_vrr_is_capable() if the platform doesn't support VRR at all Check HAS_VRR() before wasting time on the other checks. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-23-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Update the intel_vrr_extra_vblank_delay() comment

2025-10-24T21:10:58Z

The coment in intel_vrr_extra_vblank_delay() is a bit outdated now that we generally got rid of the "vblank delay" stuff. Update the comment to better describe the current state of things. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-22-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Nuke intel_vrr_vmin_flipline()

2025-10-24T21:10:58Z

Now that intel_vrr_flipline_offset() is completely hidden from the higher level VRR code, intel_vrr_vmin_flipline() has become rather pointless. Remove it. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-21-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Nuke intel_vrr_vblank_exit_length()

2025-10-24T21:10:58Z

Now that we always populate crtc_state->vrr.guardband even on ICL/TGL intel_vrr_vblank_exit_length() has become rather pointless. Get rid of it. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-20-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: s/crtc_state/old_crtc_state/ in intel_vrr_transcoder_disable()

2025-10-24T21:10:58Z

We generally use the 'old_crtc_state' in the disable functions to make it clear these generally get called when the hardware is still using the old crtc state rather than the new crtc state. Rename the intel_vrr_transcoder_disable() 'crtc_state' parameter to 'old_crtc_state' for consistency. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-19-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Move HAS_VRR() check into intel_vrr_set_transcoder_timings()

2025-10-24T21:10:58Z

Reduce the clutter in hsw_configure_cpu_transcoder() a bit by moving the HAS_VRR() check into intel_vrr_set_transcoder_timings(). Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-18-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Remove redundant HAS_VRR() checks

2025-10-24T21:10:58Z

intel_vrr_transcoder_{enable,disable}() already check for intel_vrr_possible(), so the extra HAS_VRR() checks are redundant. Remove them. Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-17-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal

drm/i915/vrr: Always write TRANS_VRR_CTL in intel_vrr_set_transcoder_timings() on !always_use_vrr_tg()

2025-10-24T21:10:58Z

Currently, depending on vrr.enable, we may write TRANS_VRR_CTL from both intel_vrr_set_transcoder_timings() and intel_vrr_transcoder_enable() on !always_use_vrr_tg() platforms. Streamline this so that we just always write it from intel_vrr_set_transcoder_timings(), and never from intel_vrr_transcoder_enable(). The main benefit is that intel_vrr_transcoder_enable() becomes symmetric to intel_vrr_transcoder_disable(). Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20251020185038.4272-16-ville.syrjala@linux.intel.com Reviewed-by: Ankit Nautiyal