Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
Pre-existing issues: - [High] Modifying hardware state and global driver state during the atomic_check phase. - [High] drm_atomic_get_bridge_state() error code masking breaks wait/wound mutex backoff. -- commit d0dd6a8692e00076c21b4fe6dcb51ded1a0bb7d0 Author: Cristian Ciocaltea <[email protected]> drm/rockchip: dw_hdmi_qp: Support 10-bit YUV422 output format This commit adds support for the 10-bit YUV422 output format to the Rockchip DW HDMI QP encoder. It also configures the HDMI PHY with 8 bpc when YUV422 is in use to keep its output clock aligned with the TMDS character rate. > diff --git a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c > b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c > index 9c4cf68d79d50..78473f9a0fce3 100644 > --- a/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c > +++ b/drivers/gpu/drm/rockchip/dw_hdmi_qp-rockchip.c [ ... ] > @@ -226,7 +227,14 @@ dw_hdmi_qp_rockchip_encoder_atomic_check(struct > drm_encoder *encoder, > } > > phy_cfg.hdmi.tmds_char_rate = conn_state->hdmi.tmds_char_rate; > - phy_cfg.hdmi.bpc = conn_state->hdmi.output_bpc; > + /* > + * YUV422 always transmits two 12-bit components per clock cycle, > + * regardless of the color depth, which from a rate perspective is > + * equivalent to three 8-bit RGB components. Force 8 bpc here to > + * keep the PHY PLL output aligned with the TMDS character rate. > + */ > + phy_cfg.hdmi.bpc = (s->output_mode == ROCKCHIP_OUT_MODE_YUV422 ? > + 8 : conn_state->hdmi.output_bpc); > > ret = phy_configure(hdmi->phy, &phy_cfg); > if (!ret) { [Severity: High] This isn't a bug introduced by this patch, but does calling phy_configure() and modifying hdmi->tmds_char_rate inside atomic_check illegally commit changes to global hardware tracking state? In the DRM atomic KMS framework, atomic_check callbacks must be strictly stateless and free of side-effects because they are frequently executed during test-only commits intended purely to validate configurations. By calling phy_configure() here, the driver incorrectly modifies physical hardware registers during a test phase, which can cause display glitches, sync loss, or hardware lockups. Additionally, upon success, the function updates the global state: if (!ret) { hdmi->tmds_char_rate = conn_state->hdmi.tmds_char_rate; s->output_type = DRM_MODE_CONNECTOR_HDMIA; This permanently corrupts the driver's cached state. A subsequent real commit may skip hardware configuration entirely because hdmi->tmds_char_rate matches the requested rate, leaving the device out of sync and breaking display output. This fundamentally breaks compositors that rely on test-only commits. There is also another pre-existing issue earlier in the same function: dw_hdmi_qp_rockchip_encoder_atomic_check() { ... ingest_fmt = dw_hdmi_qp_rockchip_get_vop_format(encoder, conn_state); if (ingest_fmt < 0) return -EINVAL; ... } [Severity: High] This is a pre-existing issue, but does swallowing the error code here break the wait/wound mutex backoff mechanism? dw_hdmi_qp_rockchip_get_vop_format() calls drm_atomic_get_bridge_state(), which uses wait/wound mutexes to lock bridge states and can return -EDEADLK if the lock is contended. Returning -EDEADLK signals the DRM core to back off, drop all locks, and retry the commit. By checking if (ingest_fmt < 0) and returning a hardcoded -EINVAL, the -EDEADLK error is swallowed. This breaks the DRM atomic commit WW mutex backoff mechanism, causing valid userspace commits to fail spuriously with -EINVAL under lock contention when multiple threads or processes attempt atomic commits concurrently. -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=12
