From 7d7f60b8b5e34341aac5d0517259e51e64a2c52e Mon Sep 17 00:00:00 2001
From: Daniel Thompson <daniel.thompson@linaro.org>
Date: Tue, 1 Feb 2022 17:47:32 +0000
Subject: drm/msm/dsi: Remove spurious IRQF_ONESHOT flag
Git-commit: 24b176d8827d167ac3b379317f60c0985f6e95aa
Patch-mainline: v5.18-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
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>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220201174734.196718-2-daniel.thompson@linaro.org
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
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 8b15280261b8..be474dcdc9bc 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",
--
2.38.1