Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [High] drm/i915/alpm: uninitialized mutex lock in intel_alpm_lobf_disable() --
commit 3691f816d97c5d3f84209f1900c4bc02406c352b Author: Animesh Manna <[email protected]> drm/i915/alpm: Replace is_edp() with alpm_is_possible() This commit introduces intel_alpm_is_possible() to check ALPM capability from DPCD and LTTPR info instead of checking intel_dp_is_edp() in intel_alpm_lobf_compute_config(). It also removes the intel_dp_is_edp() checks from intel_alpm_lobf_enable() and intel_alpm_lobf_disable(). > diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c > b/drivers/gpu/drm/i915/display/intel_alpm.c > index 4e761022485d7..205f1ae10d431 100644 > --- a/drivers/gpu/drm/i915/display/intel_alpm.c > +++ b/drivers/gpu/drm/i915/display/intel_alpm.c [ ... ] > @@ -829,9 +848,6 @@ void intel_alpm_lobf_disable(const struct > intel_crtc_state *new_crtc_state) > > intel_dp = enc_to_intel_dp(encoder); > > - if (!intel_dp_is_edp(intel_dp)) > - continue; > - > mutex_lock(&intel_dp->alpm.lock); > intel_de_write(display, ALPM_CTL(display, cpu_transcoder), 0); > drm_dbg_kms(display->drm, "Link off between frames (LOBF) > disabled\n"); [Severity: High] Can removing the intel_dp_is_edp() check in intel_alpm_lobf_disable() cause mutex_lock(&intel_dp->alpm.lock) to be called on an uninitialized mutex? In drivers/gpu/drm/i915/display/intel_alpm.c, intel_alpm_init() only initializes alpm.lock when intel_alpm_source_supported(intel_dp) is true: void intel_alpm_init(struct intel_dp *intel_dp) { if (!intel_alpm_source_supported(intel_dp)) return; mutex_init(&intel_dp->alpm.lock); } On platforms with DISPLAY_VER between 20 and 34, intel_alpm_source_supported() is only true for eDP encoders, so non-eDP DP encoders leave alpm.lock uninitialized. In drivers/gpu/drm/i915/display/intel_display.c, intel_pre_plane_update() checks whether LOBF is being disabled via intel_crtc_lobf_disabling(), which inspects old_crtc_state->has_lobf, but then passes new_crtc_state to intel_alpm_lobf_disable(): if (intel_crtc_lobf_disabling(old_crtc_state, new_crtc_state)) intel_alpm_lobf_disable(new_crtc_state); If a CRTC with LOBF active on an eDP encoder (old_crtc_state->has_lobf is true) is switched in an atomic modeset to a non-eDP DP encoder (new_crtc_state->has_lobf is false), intel_alpm_lobf_disable() iterates over new_crtc_state->uapi.encoder_mask and calls mutex_lock(&intel_dp->alpm.lock) on the non-eDP encoder whose mutex was never initialized. Additionally, because intel_alpm_lobf_disable() inspects new_crtc_state rather than old_crtc_state, disabling a CRTC by detaching its connector (leaving new_crtc_state->uapi.encoder_mask empty) skips the loop and leaves ALPM_CTL enabled, or on DISPLAY_VER >= 35 locks the new encoder's alpm.lock instead of the old encoder's. Should intel_pre_plane_update() pass old_crtc_state to intel_alpm_lobf_disable(const struct intel_crtc_state *old_crtc_state) so it operates on the encoder and transcoder where LOBF was previously enabled? -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=16
