2022-10-13 11:08:13

by Pin-yen Lin

Subject: [PATCH v2 1/3] drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe

During device boot, the HPD interrupt could be triggered before the DRM
subsystem registers it6505 as a DRM bridge. In such cases, the driver
tries to access AUX channel and causes NULL pointer dereference.
Initializing the AUX channel earlier to prevent such error.

Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
Signed-off-by: Pin-yen Lin <[email protected]>
---

(no changes since v1)

drivers/gpu/drm/bridge/ite-it6505.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index a4302492cf8d..f7f6c3e20fae 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -2871,10 +2871,7 @@ static int it6505_bridge_attach(struct drm_bridge *bridge,
}

/* Register aux channel */
- it6505->aux.name = "DP-AUX";
- it6505->aux.dev = dev;
it6505->aux.drm_dev = bridge->dev;
- it6505->aux.transfer = it6505_aux_transfer;

ret = drm_dp_aux_register(&it6505->aux);

@@ -3354,6 +3351,11 @@ static int it6505_i2c_probe(struct i2c_client *client,
debugfs_init(it6505);
pm_runtime_enable(dev);

+ it6505->aux.name = "DP-AUX";
+ it6505->aux.dev = dev;
+ it6505->aux.transfer = it6505_aux_transfer;
+ drm_dp_aux_init(&it6505->aux);
+
it6505->bridge.funcs = &it6505_bridge_funcs;
it6505->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
it6505->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
--
2.38.0.rc1.362.ged0d419d3c-goog

2022-10-24 08:03:19

by Robert Foss

Subject: Re: [PATCH v2 1/3] drm/bridge: it6505: Initialize AUX channel in it6505_i2c_probe

On Thu, 13 Oct 2022 at 13:04, Pin-yen Lin <[email protected]> wrote:
>
> During device boot, the HPD interrupt could be triggered before the DRM
> subsystem registers it6505 as a DRM bridge. In such cases, the driver
> tries to access AUX channel and causes NULL pointer dereference.
> Initializing the AUX channel earlier to prevent such error.
>
> Fixes: b5c84a9edcd4 ("drm/bridge: add it6505 driver")
> Signed-off-by: Pin-yen Lin <[email protected]>
> ---
>
> (no changes since v1)
>
> drivers/gpu/drm/bridge/ite-it6505.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
> index a4302492cf8d..f7f6c3e20fae 100644
> --- a/drivers/gpu/drm/bridge/ite-it6505.c
> +++ b/drivers/gpu/drm/bridge/ite-it6505.c
> @@ -2871,10 +2871,7 @@ static int it6505_bridge_attach(struct drm_bridge *bridge,
> }
>
> /* Register aux channel */
> - it6505->aux.name = "DP-AUX";
> - it6505->aux.dev = dev;
> it6505->aux.drm_dev = bridge->dev;
> - it6505->aux.transfer = it6505_aux_transfer;
>
> ret = drm_dp_aux_register(&it6505->aux);
>
> @@ -3354,6 +3351,11 @@ static int it6505_i2c_probe(struct i2c_client *client,
> debugfs_init(it6505);
> pm_runtime_enable(dev);
>
> + it6505->aux.name = "DP-AUX";
> + it6505->aux.dev = dev;
> + it6505->aux.transfer = it6505_aux_transfer;
> + drm_dp_aux_init(&it6505->aux);
> +
> it6505->bridge.funcs = &it6505_bridge_funcs;
> it6505->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
> it6505->bridge.ops = DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID |
> --
> 2.38.0.rc1.362.ged0d419d3c-goog
>

Reviewed-by: Robert Foss <[email protected]>