linux-kernel - [RFT PATCH 10/15] drm/sprd: Call drm_atomic_helper

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Message-ID: <20230901164111.RFT.10.I7a2dd349cb52bae53280d0a49e22cc27b923274b@changeid>
Date:   Fri,  1 Sep 2023 16:41:21 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     dri-devel@...ts.freedesktop.org, Maxime Ripard <mripard@...nel.org>
Cc:     Douglas Anderson <dianders@...omium.org>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>, airlied@...il.com,
        daniel@...ll.ch, linux-kernel@...r.kernel.org, liviu.dudau@....com,
        orsonzhai@...il.com, rfoss@...nel.org, robh@...nel.org,
        sam@...nborg.org, steven.price@....com, tzimmermann@...e.de,
        zhang.lyra@...il.com
Subject: [RFT PATCH 10/15] drm/sprd: Call drm_atomic_helper_shutdown() at remove time

Based on grepping through the source code, this driver appears to be
missing a call to drm_atomic_helper_shutdown() at remove time. Let's
add it.

The fact that we should call drm_atomic_helper_shutdown() in the case
of OS driver remove comes straight out of the kernel doc "driver
instance overview" in drm_drv.c.

While at it, let's also fix it so that if the driver's bind fails or
if a driver gets unbound that the drvdata gets set to NULL. This will
make sure we can't get confused during a later shutdown().

Suggested-by: Maxime Ripard <mripard@...nel.org>
Signed-off-by: Douglas Anderson <dianders@...omium.org>
---
This commit is only compile-time tested.

While making this patch, I noticed that the bind() function of this
driver is using "devm". That's actually a bug. As per kernel docs [1]
"the lifetime of the aggregate driver does not align with any of the
underlying struct device instances. Therefore devm cannot be used and
all resources acquired or allocated in this callback must be
explicitly released in the unbind callback". Fixing that is outside
the scope of this commit.

[1] https://docs.kernel.org/driver-api/component.html

 drivers/gpu/drm/sprd/sprd_drm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/sprd/sprd_drm.c b/drivers/gpu/drm/sprd/sprd_drm.c
index 0aa39156f2fa..86a175116140 100644
--- a/drivers/gpu/drm/sprd/sprd_drm.c
+++ b/drivers/gpu/drm/sprd/sprd_drm.c
@@ -114,6 +114,7 @@ static int sprd_drm_bind(struct device *dev)
 	drm_kms_helper_poll_fini(drm);
 err_unbind_all:
 	component_unbind_all(drm->dev, drm);
+	platform_set_drvdata(pdev, NULL);
 	return ret;
 }

@@ -122,10 +123,11 @@ static void sprd_drm_unbind(struct device *dev)
 	struct drm_device *drm = dev_get_drvdata(dev);

 	drm_dev_unregister(drm);
-
 	drm_kms_helper_poll_fini(drm);
+	drm_atomic_helper_shutdown(drm);

 	component_unbind_all(drm->dev, drm);
+	dev_set_drvdata(dev, NULL);
 }

 static const struct component_master_ops drm_component_ops = {
-- 
2.42.0.283.g2d96d420d3-goog