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drm/panel: panel-simple: make panel_dpi_probe return a panel_desc

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If the panel-simple driver is probed from a panel-dpi compatible, the
driver will use an empty panel_desc structure as a descriminant. It
will then allocate and fill another panel_desc as part of its probe.

However, that allocation needs to happen after the panel_simple
structure has been allocated, since panel_dpi_probe(), the function
doing the panel_desc allocation and initialization, takes a panel_simple
pointer as an argument.

This pointer is used to fill the panel_simple->desc pointer that is
still initialized with the empty panel_desc when panel_dpi_probe() is
called.

Since commit de04bb0089 ("drm/panel/panel-simple: Use the new
allocation in place of devm_kzalloc()"), we will need the panel
connector type found in panel_desc to allocate panel_simple. This
creates a circular dependency where we need panel_desc to create
panel_simple, and need panel_simple to create panel_desc.

Let's break that dependency by making panel_dpi_probe simply return the
panel_desc it initialized and move the panel_simple->desc assignment to
the caller.

This will not fix the breaking commit entirely, but will move us towards
the right direction.

Fixes: de04bb0089 ("drm/panel/panel-simple: Use the new allocation in place of devm_kzalloc()")
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Francesco Dolcini <francesco.dolcini@toradex.com> # Toradex Colibri iMX6
Link: https://lore.kernel.org/r/20250626-drm-panel-simple-fixes-v2-2-5afcaa608bdc@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>
This commit is contained in:
Maxime Ripard 2025-06-26 12:05:00 +02:00
parent 2d22b63f3a
commit 073667fce1
No known key found for this signature in database
GPG Key ID: 275FCE19A23DBE76
1 changed files with 11 additions and 11 deletions
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22
drivers/gpu/drm/panel/panel-simple.c
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@ -432,8 +432,7 @@ static const struct drm_panel_funcs panel_simple_funcs = {
static struct panel_desc panel_dpi;
static int panel_dpi_probe(struct device *dev,
struct panel_simple *panel)
static struct panel_desc *panel_dpi_probe(struct device *dev)
{
struct display_timing *timing;
const struct device_node *np;
@ -445,17 +444,17 @@ static int panel_dpi_probe(struct device *dev,
np = dev->of_node;
desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
if (!desc)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
timing = devm_kzalloc(dev, sizeof(*timing), GFP_KERNEL);
if (!timing)
return -ENOMEM;
return ERR_PTR(-ENOMEM);
ret = of_get_display_timing(np, "panel-timing", timing);
if (ret < 0) {
dev_err(dev, "%pOF: no panel-timing node found for \"panel-dpi\" binding\n",
np);
return ret;
return ERR_PTR(ret);
}
desc->timings = timing;
@ -473,9 +472,7 @@ static int panel_dpi_probe(struct device *dev,
/* We do not know the connector for the DT node, so guess it */
desc->connector_type = DRM_MODE_CONNECTOR_DPI;
panel->desc = desc;
return 0;
return desc;
}
#define PANEL_SIMPLE_BOUNDS_CHECK(to_check, bounds, field) \
@ -613,10 +610,13 @@ static int panel_simple_probe(struct device *dev, const struct panel_desc *desc)
if (desc == &panel_dpi) {
/* Handle the generic panel-dpi binding */
err = panel_dpi_probe(dev, panel);
if (err)
desc = panel_dpi_probe(dev);
if (IS_ERR(desc)) {
err = PTR_ERR(desc);
goto free_ddc;
desc = panel->desc;
}
panel->desc = desc;
} else {
if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))
panel_simple_parse_panel_timing_node(dev, panel, &dt);