[PATCH v2 06/10] drm/msm/dp: fix aux-bus EP lifetime

Johan Hovold
2022-09-13T08:58:43Z

Device-managed resources allocated post component bind must be tied to
the lifetime of the aggregate DRM device or they will not necessarily be
released when binding of the aggregate device is deferred.

This can lead resource leaks or failure to bind the aggregate device
when binding is later retried and a second attempt to allocate the
resources is made.

For the DP aux-bus, an attempt to populate the bus a second time will
simply fail ("DP AUX EP device already populated").

Fix this by tying the lifetime of the EP device to the DRM device rather
than DP controller platform device.

Fixes: c3bf8e21b38a ("drm/msm/dp: Add eDP support via aux_bus")
Cc: stable@vger.kernel.org # 5.19
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
---
drivers/gpu/drm/msm/dp/dp_display.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
index ba557328710a..4b0a2d4bb61e 100644
--- a/drivers/gpu/drm/msm/dp/dp_display.c
+++ b/drivers/gpu/drm/msm/dp/dp_display.c
@@ -1535,6 +1535,11 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor)
}
}

+static void of_dp_aux_depopulate_bus_void(void *data)
+{
+ of_dp_aux_depopulate_bus(data);
+}
+
static int dp_display_get_next_bridge(struct msm_dp *dp)
{
int rc;
@@ -1559,10 +1564,16 @@ static int dp_display_get_next_bridge(struct msm_dp *dp)
* panel driver is probed asynchronously but is the best we
* can do without a bigger driver reorganization.
*/
- rc = devm_of_dp_aux_populate_ep_devices(dp_priv->aux);
+ rc = of_dp_aux_populate_bus(dp_priv->aux, NULL);
of_node_put(aux_bus);
if (rc)
goto error;
+
+ rc = devm_add_action_or_reset(dp->drm_dev->dev,
+ of_dp_aux_depopulate_bus_void,
+ dp_priv->aux);
+ if (rc)
+ goto error;
} else if (dp->is_edp) {
DRM_ERROR("eDP aux_bus not found\n");
return -ENODEV;
--
2.35.1