On 07.01.2026 14:13, Luca Ceresoli wrote:
> In preparation to handle refcounting of the out_bridge, we need to ensure
> the out_bridge pointer contains either a valid bridge pointer or NULL, not
> an ERR_PTR. Otherwise calls such as drm_bridge_get/put() would try to
> redeference an ERR_PTR.
>
> As a preliminary cleanup, add a temporary local 'next_bridge' pointer and
> only copy it in dsi->out_bridge when returning successfully.
>
> Signed-off-by: Luca Ceresoli <[email protected]>
> ---
> drivers/gpu/drm/bridge/samsung-dsim.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
> b/drivers/gpu/drm/bridge/samsung-dsim.c
> index eabc4c32f6ab..b3003aa49dc3 100644
> --- a/drivers/gpu/drm/bridge/samsung-dsim.c
> +++ b/drivers/gpu/drm/bridge/samsung-dsim.c
> @@ -1886,6 +1886,7 @@ static int samsung_dsim_host_attach(struct
> mipi_dsi_host *host,
> {
> struct samsung_dsim *dsi = host_to_dsi(host);
> const struct samsung_dsim_plat_data *pdata = dsi->plat_data;
> + struct drm_bridge *next_bridge;
> struct device *dev = dsi->dev;
> struct device_node *np = dev->of_node;
> struct device_node *remote;
> @@ -1924,17 +1925,17 @@ static int samsung_dsim_host_attach(struct
> mipi_dsi_host *host,
>
> panel = of_drm_find_panel(remote);
> if (!IS_ERR(panel)) {
> - dsi->out_bridge = devm_drm_panel_bridge_add(dev, panel);
> + next_bridge = devm_drm_panel_bridge_add(dev, panel);
> } else {
> - dsi->out_bridge = of_drm_find_bridge(remote);
> - if (!dsi->out_bridge)
> - dsi->out_bridge = ERR_PTR(-EINVAL);
> + next_bridge = of_drm_find_bridge(remote);
> + if (!next_bridge)
> + next_bridge = ERR_PTR(-EINVAL);
> }
>
> of_node_put(remote);
>
> - if (IS_ERR(dsi->out_bridge)) {
> - ret = PTR_ERR(dsi->out_bridge);
> + if (IS_ERR(next_bridge)) {
> + ret = PTR_ERR(next_bridge);
> DRM_DEV_ERROR(dev, "failed to find the bridge: %d\n", ret);
> return ret;
> }
> @@ -1967,6 +1968,7 @@ static int samsung_dsim_host_attach(struct
> mipi_dsi_host *host,
> dsi->lanes = device->lanes;
> dsi->format = device->format;
> dsi->mode_flags = device->mode_flags;
> + dsi->out_bridge = next_bridge;
>
This assignment is too late, dsi->out_bridge is used (indirectly, by
samsung_dsim_attach() called from drm_bridge_attach()) by
ret = pdata->host_ops->attach(dsi, device);
a few lines before this assignment, so the following fix has to be added:
diff --git a/drivers/gpu/drm/bridge/samsung-dsim.c
b/drivers/gpu/drm/bridge/samsung-dsim.c index b3003aa49dc3..f88aa8ab2879
100644 --- a/drivers/gpu/drm/bridge/samsung-dsim.c +++
b/drivers/gpu/drm/bridge/samsung-dsim.c @@ -1959,6 +1959,7 @@ static int
samsung_dsim_host_attach(struct mipi_dsi_host *host, return ret; } +
dsi->out_bridge = next_bridge; if (pdata->host_ops &&
pdata->host_ops->attach) { ret = pdata->host_ops->attach(dsi, device);
if (ret) @@ -1968,7 +1969,6 @@ static int
samsung_dsim_host_attach(struct mipi_dsi_host *host, dsi->lanes =
device->lanes; dsi->format = device->format; dsi->mode_flags =
device->mode_flags; - dsi->out_bridge = next_bridge; return 0; }
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
