[PATCH AUTOSEL 5.15 21/35] drm/exynos: Call drm_atomic_helper_shutdown() at shutdown/unbind time

Sasha Levin
2024-01-22T15:13:57Z

From: Douglas Anderson <dianders@chromium.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@kernel.org>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 d8f1cf4d6b69..2a7f96237f95 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
@@ -324,6 +324,7 @@ 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);

@@ -338,6 +339,7 @@ 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);
@@ -375,9 +377,18 @@ 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