There are some cases in intel_ddi.c, such as in intel_ddi_is_audio_enabled and intel_ddi_compute_config_late, where we attempt to perform a BIT shift using a passed transcoder enum value. This value may be -1, INVALID_TRANSCODER, which can result in undefined behavior if this occurs.
In the former case, we can simply return false if this is the transcoder passed (as audio is not enabled on an invalid transcoder). In the latter case, the likely expected behavior is to set the crtc_state->sync_mode_slaves_mask to zero, so just do that directly and avoid a risky bit shift. The likelihood of either case occurring during normal execution is unknown and possibly very low. Regardless, this covers a static analyis issue. v2: Rewrite the latter case to streamline it (Ville) v3: Target cpu_transcoder in intel_ddi_compute_config_late change (Jani) Signed-off-by: Jonathan Cavitt <[email protected]> Cc: Ville Syrjälä <[email protected]> Cc: Jani Nikula <[email protected]> --- drivers/gpu/drm/i915/display/intel_ddi.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c index 9b3b526e5e55..2bfbb6297b5d 100644 --- a/drivers/gpu/drm/i915/display/intel_ddi.c +++ b/drivers/gpu/drm/i915/display/intel_ddi.c @@ -3893,7 +3893,8 @@ static void intel_ddi_set_idle_link_train(struct intel_dp *intel_dp, static bool intel_ddi_is_audio_enabled(struct intel_display *display, enum transcoder cpu_transcoder) { - if (cpu_transcoder == TRANSCODER_EDP) + if (cpu_transcoder == TRANSCODER_EDP || + cpu_transcoder == INVALID_TRANSCODER) return false; if (!intel_display_power_is_enabled(display, POWER_DOMAIN_AUDIO_MMIO)) @@ -4679,6 +4680,10 @@ static int intel_ddi_compute_config_late(struct intel_atomic_state *state, if (crtc_state->master_transcoder == crtc_state->cpu_transcoder) { crtc_state->master_transcoder = INVALID_TRANSCODER; + if (crtc_state->cpu_transcoder == INVALID_TRANSCODER) { + crtc_state->sync_mode_slaves_mask = 0; + return 0; + } crtc_state->sync_mode_slaves_mask = port_sync_transcoders & ~REG_BIT(crtc_state->cpu_transcoder); } -- 2.53.0
