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drm/bridge: samsung-dsim: samsung_dsim_host_attach: use a temporary variable for the next bridge

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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 as late as possible, i.e. just before
calling pdata->host_ops->attach() which uses it (only in the exynos
driver).

Not strictly needed, but for symmetry move the clearing of dsi->out_bridge
in samsung_dsim_host_detach() to after pdata->host_ops->detach().

Acked-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://patch.msgid.link/20260109-drm-bridge-alloc-getput-drm_of_find_bridge-2-v2-10-8bad3ef90b9f@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
This commit is contained in:
Luca Ceresoli
2026-01-09 08:31:41 +01:00
parent 32529d384c
commit e5e1a00007
1 changed files with 17 additions and 9 deletions
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26
drivers/gpu/drm/bridge/samsung-dsim.c
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@@ -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;
}
@@ -1958,10 +1959,13 @@ static int samsung_dsim_host_attach(struct mipi_dsi_host *host,
return ret;
}
// The next bridge can be used by host_ops->attach
dsi->out_bridge = next_bridge;
if (pdata->host_ops && pdata->host_ops->attach) {
ret = pdata->host_ops->attach(dsi, device);
if (ret)
return ret;
goto err_release_next_bridge;
}
dsi->lanes = device->lanes;
@@ -1969,6 +1973,10 @@ static int samsung_dsim_host_attach(struct mipi_dsi_host *host,
dsi->mode_flags = device->mode_flags;
return 0;
err_release_next_bridge:
dsi->out_bridge = NULL;
return ret;
}
static void samsung_dsim_unregister_te_irq(struct samsung_dsim *dsi)
@@ -1985,11 +1993,11 @@ static int samsung_dsim_host_detach(struct mipi_dsi_host *host,
struct samsung_dsim *dsi = host_to_dsi(host);
const struct samsung_dsim_plat_data *pdata = dsi->plat_data;
dsi->out_bridge = NULL;
if (pdata->host_ops && pdata->host_ops->detach)
pdata->host_ops->detach(dsi, device);
dsi->out_bridge = NULL;
samsung_dsim_unregister_te_irq(dsi);
drm_bridge_remove(&dsi->bridge);