Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
New issues: - [Low] Final Result: The clock framework logs '(null)' during enablement failures because the .id fields in the clk_bulk_data array are not initialized. Pre-existing issues: - [High] Final Result: Hardware accesses on explicitly disabled clocks trigger synchronous external aborts. Ignored return values from pm_runtime_get_sync() and malidp_runtime_pm_resume() combine with the new clock rollback to guarantee an APB bus hang. - [High] Final Result: Missing synchronize_irq() in the runtime suspend path allows active shared IRQ handlers to crash the system by accessing powered-down hardware. -- commit 049d634e1eb44e14ba4f4fc2612f50ff9b67236e Author: Gustavo Kenji Mendonça Kaneko <[email protected]> drm/arm/malidp: use clk_bulk API in runtime PM resume and suspend This commit converts the Mali DP driver's runtime PM resume and suspend paths to use the clk_bulk API. It ensures that clk_bulk_prepare_enable() return values are checked during resume, rolling back any successfully enabled clocks if a failure occurs. Link: https://patch.msgid.link/[email protected] > diff --git a/drivers/gpu/drm/arm/malidp_drv.c > b/drivers/gpu/drm/arm/malidp_drv.c > index bc5f5e9798c32..2bf4a647e4b28 100644 > --- a/drivers/gpu/drm/arm/malidp_drv.c > +++ b/drivers/gpu/drm/arm/malidp_drv.c > @@ -669,6 +669,11 @@ static int malidp_runtime_pm_suspend(struct device *dev) > struct drm_device *drm = dev_get_drvdata(dev); > struct malidp_drm *malidp = drm_to_malidp(drm); > struct malidp_hw_device *hwdev = malidp->dev; > + struct clk_bulk_data clks[] = { > + { .clk = hwdev->pclk }, > + { .clk = hwdev->aclk }, > + { .clk = hwdev->mclk }, > + }; > > /* we can only suspend if the hardware is in config mode */ > WARN_ON(!hwdev->hw->in_config_mode(hwdev)); > @@ -676,9 +681,7 @@ static int malidp_runtime_pm_suspend(struct device *dev) > malidp_se_irq_fini(hwdev); > malidp_de_irq_fini(hwdev); > hwdev->pm_suspended = true; > - clk_disable_unprepare(hwdev->mclk); > - clk_disable_unprepare(hwdev->aclk); > - clk_disable_unprepare(hwdev->pclk); > + clk_bulk_disable_unprepare(ARRAY_SIZE(clks), clks); [Severity: High] This is a pre-existing issue, but is there a risk of a shared interrupt firing exactly as the device enters runtime suspend? The omission of synchronize_irq() before clk_bulk_disable_unprepare() allows concurrently executing handlers to read unclocked registers. For example, in drivers/gpu/drm/arm/malidp_hw.c: malidp_de_irq() { if (hwdev->pm_suspended) return IRQ_NONE; ... } Could we add a call to synchronize_irq() before disabling the clocks so active shared IRQ handlers do not crash the system by accessing powered-down hardware? > > return 0; > } > @@ -688,10 +691,17 @@ static int malidp_runtime_pm_resume(struct device *dev) > struct drm_device *drm = dev_get_drvdata(dev); > struct malidp_drm *malidp = drm_to_malidp(drm); > struct malidp_hw_device *hwdev = malidp->dev; > + struct clk_bulk_data clks[] = { > + { .clk = hwdev->pclk }, > + { .clk = hwdev->aclk }, > + { .clk = hwdev->mclk }, > + }; [Severity: Low] Does this array initialization cause the clock framework to log (null) during enablement failures? If a clock fails to enable during PM resume, the uninitialized .id fields in the local clk_bulk_data array are used by pr_err(), which results in useless error logging instead of the clock name. Should we add the corresponding .id string values to this array? > + int err; > + > + err = clk_bulk_prepare_enable(ARRAY_SIZE(clks), clks); > + if (err) > + return err; [Severity: High] This is a pre-existing issue, but can the new clock rollback here cause an APB bus hang on failure? If a clock enablement fails during malidp_runtime_pm_resume(), the newly introduced clk_bulk_prepare_enable() rolls back and disables all clocks on partial failure. However, callers blindly proceed and ignore the return values from pm_runtime_get_sync() and malidp_runtime_pm_resume(), meaning they will read and write unclocked MMIO registers. For example, in drivers/gpu/drm/arm/malidp_drv.c: malidp_atomic_commit_tail() { pm_runtime_get_sync(drm->dev); ... atomic_set(&malidp->config_valid, MALIDP_CONFIG_START); malidp->dev->hw->set_config_valid(malidp->dev, 0); } Are we able to check the return value of pm_runtime_get_sync() in these callers to prevent a synchronous external abort when the resume path fails? > > - clk_prepare_enable(hwdev->pclk); > - clk_prepare_enable(hwdev->aclk); > - clk_prepare_enable(hwdev->mclk); > hwdev->pm_suspended = false; > malidp_de_irq_hw_init(hwdev); > malidp_se_irq_hw_init(hwdev); -- Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1
