linux-kernel - [PATCH AUTOSEL 5.4 15/24] drm/exynos: Call drm_atomic_helper

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Date: Mon, 22 Jan 2024 10:16:29 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Douglas Anderson <dianders@...omium.org>,
	Maxime Ripard <mripard@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Inki Dae <inki.dae@...sung.com>,
	Sasha Levin <sashal@...nel.org>,
	sw0312.kim@...sung.com,
	kyungmin.park@...sung.com,
	airlied@...il.com,
	daniel@...ll.ch,
	krzysztof.kozlowski@...aro.org,
	dri-devel@...ts.freedesktop.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 15/24] drm/exynos: Call drm_atomic_helper_shutdown() at shutdown/unbind time

From: Douglas Anderson <dianders@...omium.org>

[ Upstream commit 16ac5b21b31b439f03cdf44c153c5f5af94fb3eb ]

Based on grepping through the source code this driver appears to be
missing a call to drm_atomic_helper_shutdown() at system shutdown time
and at driver unbind time. Among other things, this means that if a
panel is in use that it won't be cleanly powered off at system
shutdown time.

The fact that we should call drm_atomic_helper_shutdown() in the case
of OS shutdown/restart and at driver remove (or unbind) time comes
straight out of the kernel doc "driver instance overview" in
drm_drv.c.

A few notes about this fix:
- When adding drm_atomic_helper_shutdown() to the unbind path, I added
  it after drm_kms_helper_poll_fini() since that's when other drivers
  seemed to have it.
- Technically with a previous patch, ("drm/atomic-helper:
  drm_atomic_helper_shutdown(NULL) should be a noop"), we don't
  actually need to check to see if our "drm" pointer is NULL before
  calling drm_atomic_helper_shutdown(). We'll leave the "if" test in,
  though, so that this patch can land without any dependencies. It
  could potentially be removed later.
- This patch also makes sure to set the drvdata to NULL in the case of
  bind errors to make sure that shutdown can't access freed data.

Suggested-by: Maxime Ripard <mripard@...nel.org>
Reviewed-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
Tested-by: Marek Szyprowski <m.szyprowski@...sung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@...sung.com>
Signed-off-by: Inki Dae <inki.dae@...sung.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/exynos/exynos_drm_drv.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
index ba0f868b2477..29577a7eaea8 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -346,6 +346,7 @@ static int exynos_drm_bind(struct device *dev)
 	drm_mode_config_cleanup(drm);
 	exynos_drm_cleanup_dma(drm);
 	kfree(private);
+	dev_set_drvdata(dev, NULL);
 err_free_drm:
 	drm_dev_put(drm);
 
@@ -360,6 +361,7 @@ static void exynos_drm_unbind(struct device *dev)
 
 	exynos_drm_fbdev_fini(drm);
 	drm_kms_helper_poll_fini(drm);
+	drm_atomic_helper_shutdown(drm);
 
 	component_unbind_all(drm->dev, drm);
 	drm_mode_config_cleanup(drm);
@@ -397,9 +399,18 @@ static int exynos_drm_platform_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static void exynos_drm_platform_shutdown(struct platform_device *pdev)
+{
+	struct drm_device *drm = platform_get_drvdata(pdev);
+
+	if (drm)
+		drm_atomic_helper_shutdown(drm);
+}
+
 static struct platform_driver exynos_drm_platform_driver = {
 	.probe	= exynos_drm_platform_probe,
 	.remove	= exynos_drm_platform_remove,
+	.shutdown = exynos_drm_platform_shutdown,
 	.driver	= {
 		.name	= "exynos-drm",
 		.pm	= &exynos_drm_pm_ops,
-- 
2.43.0