As pointed out by the documentation for drm_dp_aux_register(),
drm_dp_aux_init() should be used in situations where the AUX channel for a
display driver can potentially be registered before it's respective DRM
driver. This is the case with Tegra, since the DP aux channel exists as a
platform device instead of being a grandchild of the DRM device.
Since we're about to add a backpointer to a DP AUX channel's respective DRM
device, let's fix this so that we don't potentially allow userspace to use
the AUX channel before we've associated it with it's DRM connector.
Signed-off-by: Lyude Paul <[email protected]>
---
drivers/gpu/drm/tegra/dpaux.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 105fb9cdbb3b..ea56c6ec25e4 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -534,9 +534,7 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
dpaux->aux.transfer = tegra_dpaux_transfer;
dpaux->aux.dev = &pdev->dev;
- err = drm_dp_aux_register(&dpaux->aux);
- if (err < 0)
- return err;
+ drm_dp_aux_init(&dpaux->aux);
/*
* Assume that by default the DPAUX/I2C pads will be used for HDMI,
@@ -589,8 +587,6 @@ static int tegra_dpaux_remove(struct platform_device *pdev)
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
- drm_dp_aux_unregister(&dpaux->aux);
-
mutex_lock(&dpaux_lock);
list_del(&dpaux->list);
mutex_unlock(&dpaux_lock);
@@ -723,6 +719,10 @@ int drm_dp_aux_attach(struct drm_dp_aux *aux, struct tegra_output *output)
unsigned long timeout;
int err;
+ err = drm_dp_aux_register(aux);
+ if (err < 0)
+ return err;
+
output->connector.polled = DRM_CONNECTOR_POLL_HPD;
dpaux->output = output;
@@ -760,6 +760,7 @@ int drm_dp_aux_detach(struct drm_dp_aux *aux)
unsigned long timeout;
int err;
+ drm_dp_aux_unregister(aux);
disable_irq(dpaux->irq);
if (dpaux->output->panel) {
--
2.30.2
On Fri, Mar 26, 2021 at 04:37:49PM -0400, Lyude Paul wrote:
> As pointed out by the documentation for drm_dp_aux_register(),
> drm_dp_aux_init() should be used in situations where the AUX channel for a
> display driver can potentially be registered before it's respective DRM
> driver. This is the case with Tegra, since the DP aux channel exists as a
> platform device instead of being a grandchild of the DRM device.
>
> Since we're about to add a backpointer to a DP AUX channel's respective DRM
> device, let's fix this so that we don't potentially allow userspace to use
> the AUX channel before we've associated it with it's DRM connector.
>
> Signed-off-by: Lyude Paul <[email protected]>
> ---
> drivers/gpu/drm/tegra/dpaux.c | 11 ++++++-----
> 1 file changed, 6 insertions(+), 5 deletions(-)
Acked-by: Thierry Reding <[email protected]>