From: Daniel Thompson <daniel.thompson@linaro.org> To: Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>, Abhinav Kumar <quic_abhinavk@quicinc.com> Cc: Daniel Thompson <daniel.thompson@linaro.org>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/2] drm/msm/dsi: Remove spurious IRQF_ONESHOT flag Date: Tue, 1 Feb 2022 17:47:32 +0000 [thread overview] Message-ID: <20220201174734.196718-2-daniel.thompson@linaro.org> (raw) In-Reply-To: <20220201174734.196718-1-daniel.thompson@linaro.org> Quoting the header comments, IRQF_ONESHOT is "Used by threaded interrupts which need to keep the irq line disabled until the threaded handler has been run.". When applied to an interrupt that doesn't request a threaded irq then IRQF_ONESHOT has a lesser known (undocumented?) side effect, which it to disable the forced threading of irqs (and for "normal" kernels it is a nop). In this case I can find no evidence that suppressing forced threading is intentional. Had it been intentional then a driver must adopt the raw_spinlock API in order to avoid deadlocks on PREEMPT_RT kernels (and avoid calling any kernel API that uses regular spinlocks). Fix this by removing the spurious additional flag. This change is required for my Snapdragon 7cx Gen2 tablet to boot-to-GUI with PREEMPT_RT enabled. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> --- drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 6b3ced4aaaf5d..3a3f53f0c8ae1 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1877,7 +1877,7 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi) /* do not autoenable, will be enabled later */ ret = devm_request_irq(&pdev->dev, msm_host->irq, dsi_host_irq, - IRQF_TRIGGER_HIGH | IRQF_ONESHOT | IRQF_NO_AUTOEN, + IRQF_TRIGGER_HIGH | IRQF_NO_AUTOEN, "dsi_isr", msm_host); if (ret < 0) { dev_err(&pdev->dev, "failed to request IRQ%u: %d\n", -- 2.34.1
WARNING: multiple messages have this Message-ID (diff)
From: Daniel Thompson <daniel.thompson@linaro.org> To: Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>, Abhinav Kumar <quic_abhinavk@quicinc.com> Cc: Daniel Thompson <daniel.thompson@linaro.org>, David Airlie <airlied@linux.ie>, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org Subject: [PATCH v2 1/2] drm/msm/dsi: Remove spurious IRQF_ONESHOT flag Date: Tue, 1 Feb 2022 17:47:32 +0000 [thread overview] Message-ID: <20220201174734.196718-2-daniel.thompson@linaro.org> (raw) In-Reply-To: <20220201174734.196718-1-daniel.thompson@linaro.org> Quoting the header comments, IRQF_ONESHOT is "Used by threaded interrupts which need to keep the irq line disabled until the threaded handler has been run.". When applied to an interrupt that doesn't request a threaded irq then IRQF_ONESHOT has a lesser known (undocumented?) side effect, which it to disable the forced threading of irqs (and for "normal" kernels it is a nop). In this case I can find no evidence that suppressing forced threading is intentional. Had it been intentional then a driver must adopt the raw_spinlock API in order to avoid deadlocks on PREEMPT_RT kernels (and avoid calling any kernel API that uses regular spinlocks). Fix this by removing the spurious additional flag. This change is required for my Snapdragon 7cx Gen2 tablet to boot-to-GUI with PREEMPT_RT enabled. Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> --- drivers/gpu/drm/msm/dsi/dsi_host.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/msm/dsi/dsi_host.c b/drivers/gpu/drm/msm/dsi/dsi_host.c index 6b3ced4aaaf5d..3a3f53f0c8ae1 100644 --- a/drivers/gpu/drm/msm/dsi/dsi_host.c +++ b/drivers/gpu/drm/msm/dsi/dsi_host.c @@ -1877,7 +1877,7 @@ int msm_dsi_host_init(struct msm_dsi *msm_dsi) /* do not autoenable, will be enabled later */ ret = devm_request_irq(&pdev->dev, msm_host->irq, dsi_host_irq, - IRQF_TRIGGER_HIGH | IRQF_ONESHOT | IRQF_NO_AUTOEN, + IRQF_TRIGGER_HIGH | IRQF_NO_AUTOEN, "dsi_isr", msm_host); if (ret < 0) { dev_err(&pdev->dev, "failed to request IRQ%u: %d\n", -- 2.34.1
next prev parent reply other threads:[~2022-02-01 17:49 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-02-01 17:47 [PATCH v2 0/2] drm/msm: Remove spurious IRQF_ONESHOT flags from dsi & hdmi Daniel Thompson 2022-02-01 17:47 ` Daniel Thompson 2022-02-01 17:47 ` Daniel Thompson [this message] 2022-02-01 17:47 ` [PATCH v2 1/2] drm/msm/dsi: Remove spurious IRQF_ONESHOT flag Daniel Thompson 2022-02-09 22:03 ` Dmitry Baryshkov 2022-02-09 22:03 ` Dmitry Baryshkov 2022-02-01 17:47 ` [PATCH v2 2/2] drm/msm/hdmi: " Daniel Thompson 2022-02-01 17:47 ` Daniel Thompson 2022-02-09 22:03 ` Dmitry Baryshkov 2022-02-09 22:03 ` Dmitry Baryshkov
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