Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: - [Medium] drm/imx: dc-crtc: premature clk_axi disable in dc_crtc_disable_at_boot() --
commit 8bca21cfc221adc6d10d2019ff78d5b2dc5c6e91 Author: Liu Ying <[email protected]> drm/imx: dc-crtc: Disable at boot This commit adds a dc_crtc_disable_at_boot() helper and calls it for each CRTC during driver bind to disable any running CRTCs and balance display and AXI clock usage counts before registering the DRM device. > diff --git a/drivers/gpu/drm/imx/dc/dc-crtc.c > b/drivers/gpu/drm/imx/dc/dc-crtc.c > index 0d64186a99018..5bc952d6883e1 100644 > --- a/drivers/gpu/drm/imx/dc/dc-crtc.c > +++ b/drivers/gpu/drm/imx/dc/dc-crtc.c [ ... ] > @@ -331,6 +341,48 @@ dc_crtc_atomic_disable(struct drm_crtc *crtc, struct > drm_atomic_commit *state) > spin_unlock_irq(&crtc->dev->event_lock); > } > > +int dc_crtc_disable_at_boot(struct drm_crtc *crtc) > +{ > + struct dc_drm_device *dc_drm = to_dc_drm_device(crtc->dev); > + struct dc_crtc *dc_crtc = to_dc_crtc(crtc); > + int ret; > + > + ret = pm_runtime_resume_and_get(dc_crtc->de->dev); > + if (ret < 0) { > + dc_crtc_err(crtc, "failed to get DC display engine RPM: %d\n", > + ret); > + goto out1; > + } > + > + if (!dc_fg_wait_for_frame_index_moving(dc_crtc->fg)) { > + dc_crtc_dbg(crtc, "FrameGen frame index isn't moving\n"); > + goto out2; > + } > + > + dc_crtc_dbg(crtc, "disabling FrameGen at boot\n"); > + __dc_crtc_disable_fg(crtc); > + > + if (!dc_drv_crtc_is_enabled(dc_drm, drm_crtc_index(crtc))) > + goto out2; > + > + dc_crtc_dbg(crtc, "disabling clocks at boot\n"); > + > + dc_fg_disable_clock(dc_crtc->fg); > + > + dc_drm->pe_clk_axi_needs_disable = true; > + > + dc_drv_set_crtc_disable(dc_drm, drm_crtc_index(crtc)); > + > +out2: > + pm_runtime_put(dc_crtc->de->dev); > +out1: > + /* Let CRTC(with index == 1) disablement path disable AXI clock. */ > + if (dc_drm->pe_clk_axi_needs_disable && drm_crtc_index(crtc) == 1) > + clk_disable_unprepare(dc_drm->pe->clk_axi); > + > + return ret; > +} [Severity: Medium] As reported by Sashiko on v8 [1], can dc_crtc_disable_at_boot() in drivers/gpu/drm/imx/dc/dc-crtc.c prematurely disable dc_drm->pe->clk_axi when disabling CRTC 1 fails? In dc_drm_bind(), drm_for_each_crtc() invokes dc_crtc_disable_at_boot() for CRTC 0 and then CRTC 1. When CRTC 0 was active at boot, its call sets dc_drm->pe_clk_axi_needs_disable = true and clears CRTC_ENABLED(0). When dc_crtc_disable_at_boot() then runs for CRTC 1, if pm_runtime_resume_and_get(dc_crtc->de->dev) fails and jumps to out1, CRTC 1's FrameGen has not been stopped and CRTC_ENABLED(1) has not been cleared. However, at out1, dc_drm->pe_clk_axi_needs_disable is already true from CRTC 0 and drm_crtc_index(crtc) == 1, so clk_disable_unprepare(dc_drm->pe->clk_axi) is called unconditionally. If CRTC 1 was also active at boot, wouldn't this gate the Pixel Engine AXI clock while CRTC 1 is still scanning out from the Pixel Engine, and leave CRTC_ENABLED(1) set in the general purpose register so that a subsequent bind retry disables dc_drm->pe->clk_axi a second time? [1] https://lore.kernel.org/r/[email protected] -- Sashiko AI review ยท https://sashiko.dev/#/patchset/[email protected]?part=7
