Hello Damon,
On Mon Sep 21, 2026 at 5:07 AM CEST, Damon Ding wrote:
> Hi Luca,
>
> On 9/16/2026 9:45 PM, Luca Ceresoli wrote:
>> Now a panel_bridge is automatically created for every drm_panel and the
>> panel-bridge API is just a deprecated wrapper to access it.
>>
>> Update and simplify the code by just getting a reference to the
>> already-existing bridge using of_drm_get_bridge_by_endpoint().
>>
>> As of_drm_get_bridge_by_endpoint() returns a refcounted bridge, take care
>> of putting the bridge reference. This is not easily done in the remove path
>> due to the different probe paths of the user drivers, so add a devm action
>> to ensure the reference is put only when it was taken.
>>
>> Assisted-by: opencode:deepseek-v4-flash-0731
>> Signed-off-by: Luca Ceresoli <[email protected]>
>> ---
>> drivers/gpu/drm/bridge/analogix/Kconfig | 1 -
>> drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 40
>> +++++++++++++---------
>> drivers/gpu/drm/exynos/exynos_dp.c | 36 ++-----------------
>> drivers/gpu/drm/rockchip/analogix_dp-rockchip.c | 9 -----
>> include/drm/bridge/analogix_dp.h | 1 -
>> 5 files changed, 25 insertions(+), 62 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/Kconfig
>> b/drivers/gpu/drm/bridge/analogix/Kconfig
>> index da156fd15764..5672d83cb4a1 100644
>> --- a/drivers/gpu/drm/bridge/analogix/Kconfig
>> +++ b/drivers/gpu/drm/bridge/analogix/Kconfig
>> @@ -33,7 +33,6 @@ config DRM_ANALOGIX_DP
>> depends on DRM
>> depends on OF
>> select DRM_DISPLAY_DP_AUX_BUS
>> - select DRM_PANEL
>>
>> config DRM_ANALOGIX_ANX7625
>> tristate "Analogix Anx7625 MIPI to DP interface support"
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 18e76d1e78e1..6df6963740d2 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -29,7 +29,6 @@
>> #include <drm/drm_device.h>
>> #include <drm/drm_edid.h>
>> #include <drm/drm_of.h>
>> -#include <drm/drm_panel.h>
>> #include <drm/drm_print.h>
>> #include <drm/drm_probe_helper.h>
>>
>> @@ -1567,15 +1566,6 @@ int analogix_dp_bind(struct analogix_dp_device *dp,
>> struct drm_device *drm_dev)
>> if (ret)
>> goto err_unregister_aux;
>>
>> - if (dp->plat_data->panel) {
>> - dp->plat_data->next_bridge = devm_drm_panel_bridge_add(dp->dev,
>> -
>> dp->plat_data->panel);
>> - if (IS_ERR(dp->plat_data->next_bridge)) {
>> - ret = PTR_ERR(dp->plat_data->next_bridge);
>> - goto err_unregister_aux;
>> - }
>> - }
>> -
>> ret = drm_bridge_attach(dp->encoder, bridge, NULL,
>> DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> if (ret) {
>> DRM_ERROR("failed to create bridge (%d)\n", ret);
>> @@ -1647,6 +1637,11 @@ struct drm_dp_aux *analogix_dp_get_aux(struct
>> analogix_dp_device *dp)
>> }
>> EXPORT_SYMBOL_GPL(analogix_dp_get_aux);
>>
>> +static void analogix_dp_put_bridge(void *data)
>> +{
>> + drm_bridge_put(data);
>> +}
>> +
>> static int analogix_dp_aux_done_probing(struct drm_dp_aux *aux)
>> {
>> struct analogix_dp_device *dp = to_dp(aux);
>> @@ -1655,14 +1650,25 @@ static int analogix_dp_aux_done_probing(struct
>> drm_dp_aux *aux)
>> int ret;
>>
>> /*
>> - * If drm_of_find_panel_or_bridge() returns -ENODEV, there may be no
>> valid panel
>> - * or bridge nodes. The driver should go on for the driver-free bridge
>> or the DP
>> - * mode applications.
>> + * If of_drm_get_bridge_by_endpoint() returns -ENODEV, there may be no
>> + * valid panel or bridge nodes. The driver should go on for the
>> + * driver-free bridge or the DP mode applications.
>> */
>> - ret = drm_of_find_panel_or_bridge(dp->dev->of_node, port, 0,
>> - &plat_data->panel,
>> &plat_data->next_bridge);
>> - if (ret && ret != -ENODEV)
>> - return ret;
>> + plat_data->next_bridge = of_drm_get_bridge_by_endpoint(dp->dev->of_node,
>> + port, 0);
>> + if (IS_ERR(plat_data->next_bridge)) {
>> + if (PTR_ERR(plat_data->next_bridge) == -ENODEV)
>> + plat_data->next_bridge = NULL;
>> + else
>> + return PTR_ERR(plat_data->next_bridge);
>> + }
>> +
>> + if (plat_data->next_bridge) {
>> + ret = devm_add_action_or_reset(dp->dev, analogix_dp_put_bridge,
>> + plat_data->next_bridge);
>> + if (ret)
>> + return ret;
>> + }
>>
>> return component_add(dp->dev, plat_data->ops);
>> }
>> diff --git a/drivers/gpu/drm/exynos/exynos_dp.c
>> b/drivers/gpu/drm/exynos/exynos_dp.c
>> index e1c9e2946b8a..82c238829921 100644
>> --- a/drivers/gpu/drm/exynos/exynos_dp.c
>> +++ b/drivers/gpu/drm/exynos/exynos_dp.c
>> @@ -26,7 +26,6 @@
>> #include <drm/drm_crtc.h>
>> #include <drm/drm_encoder.h>
>> #include <drm/drm_of.h>
>> -#include <drm/drm_panel.h>
>> #include <drm/drm_print.h>
>> #include <drm/drm_probe_helper.h>
>> #include <drm/exynos_drm.h>
>> @@ -147,7 +146,6 @@ static const struct component_ops exynos_dp_ops = {
>> static int exynos_dp_probe(struct platform_device *pdev)
>> {
>> struct device *dev = &pdev->dev;
>> - struct device_node *np;
>> struct exynos_dp_device *dp;
>>
>> dp = devm_kzalloc(&pdev->dev, sizeof(struct exynos_dp_device),
>> @@ -163,18 +161,6 @@ static int exynos_dp_probe(struct platform_device *pdev)
>> */
>> platform_set_drvdata(pdev, dp);
>>
>> - /* This is for the backward compatibility. */
>> - np = of_parse_phandle(dev->of_node, "panel", 0);
>> - if (np) {
>> - dp->plat_data.panel = of_drm_find_panel(np);
>> -
>> - of_node_put(np);
>> - if (IS_ERR(dp->plat_data.panel))
>> - return PTR_ERR(dp->plat_data.panel);
>> -
>> - goto out;
>> - }
>> -
>
> TIP: In my WIP v3 patch series, I use of_drm_find_panel() together with
> devm_drm_panel_bridge_add() to maintain this backward compatibility. But
> I also think this old approach should be deprecated now. Shall we add
> some notes in the commit message to mention the deprecation of this method?
What is the "WIP v3" series exactly? Do you have a link (to v2 in case v3
is not yet public)?
>> if (of_get_display_timings(dev->of_node)) {
>> dp->plat_data.next_bridge =
>> devm_drm_of_display_mode_bridge(dp->dev,
>>
>> dp->dev->of_node,
>> @@ -189,19 +175,11 @@ static int exynos_dp_probe(struct platform_device
>> *pdev)
>> dp->plat_data.power_off = exynos_dp_poweroff;
>> dp->plat_data.ops = &exynos_dp_ops;
>>
>> -out:
>> dp->adp = analogix_dp_probe(dev, &dp->plat_data);
>> - if (IS_ERR(dp->adp)) {
>> - /*
>> - * The driver core does not invoke remove() for failed probes,
>> - * so release the probe-time panel reference here.
>> - */
>> - if (dp->plat_data.panel)
>> - drm_panel_put(dp->plat_data.panel);
>> + if (IS_ERR(dp->adp))
>> return PTR_ERR(dp->adp);
>> - }
>>
>> - if (dp->plat_data.panel || dp->plat_data.next_bridge)
>> + if (dp->plat_data.next_bridge)
>> return component_add(&pdev->dev, &exynos_dp_ops);
>> else
>> return analogix_dp_finish_probe(dp->adp);
>> @@ -209,16 +187,6 @@ static int exynos_dp_probe(struct platform_device *pdev)
>>
>> static void exynos_dp_remove(struct platform_device *pdev)
>> {
>> - struct exynos_dp_device *dp = platform_get_drvdata(pdev);
>> -
>> - /*
>> - * Release the probe-time reference from of_drm_find_panel(). If bind
>> - * ran, the panel_bridge holds a second reference that devm cleanup
>> - * will release when the bridge is destroyed after remove() returns.
>> - */
>> - if (dp->plat_data.panel)
>> - drm_panel_put(dp->plat_data.panel);
>> -
>> component_del(&pdev->dev, &exynos_dp_ops);
>> }
>>
>> diff --git a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> index 587e60232ec7..071d31aa5288 100644
>> --- a/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> +++ b/drivers/gpu/drm/rockchip/analogix_dp-rockchip.c
>> @@ -28,7 +28,6 @@
>> #include <drm/drm_bridge_connector.h>
>> #include <drm/bridge/analogix_dp.h>
>> #include <drm/drm_of.h>
>> -#include <drm/drm_panel.h>
>> #include <drm/drm_print.h>
>> #include <drm/drm_probe_helper.h>
>>
>> @@ -488,14 +487,6 @@ static void rockchip_dp_remove(struct platform_device
>> *pdev)
>> {
>> struct rockchip_dp_device *dp = platform_get_drvdata(pdev);
>>
>> - /*
>> - * Release the probe-time reference from of_drm_find_panel(). If bind
>> - * ran, the panel_bridge holds a second reference that devm cleanup
>> - * will release when the bridge is destroyed after remove() returns.
>> - */
>> - if (dp->plat_data.panel)
>> - drm_panel_put(dp->plat_data.panel);
>> -
>> component_del(&pdev->dev, &rockchip_dp_component_ops);
>> }
>>
>> diff --git a/include/drm/bridge/analogix_dp.h
>> b/include/drm/bridge/analogix_dp.h
>> index 0e0b87abee59..6033137b651e 100644
>> --- a/include/drm/bridge/analogix_dp.h
>> +++ b/include/drm/bridge/analogix_dp.h
>> @@ -35,7 +35,6 @@ static inline bool analogix_dp_is_rockchip(enum
>> analogix_dp_devtype type)
>>
>> struct analogix_dp_plat_data {
>> enum analogix_dp_devtype dev_type;
>> - struct drm_panel *panel;
>> struct drm_bridge *next_bridge;
>> struct drm_encoder *encoder;
>> struct drm_connector *connector;
>>
>
> I apply this patch series with the related one[0], and the eDP work well
> on my RK3576 board.
>
> Tested-by: Damon Ding <[email protected]>
>
> In my patch series for Analogix DP HPD support, Heiko also pointed out
> that devm_drm_of_get_bridge()(deprecated now) can be used to get the
> panel bridge directly, and the redundant &analogix_dp_plat_data.panel
> can be removed[1]. Since your patch series already contains these
> optimizations, I will rebase my patch series on top of yours for
> subsequent updates.
Yes, I confirm with this series devm_drm_of_get_bridge() becomes a
complicated equivalent of of_drm_get_bridge_by_endpoint(). So what Heiko
suggested is correct for current upstream code, but this patch goes a step
further, using just the bridge API as the new recommended practice will be
as soon as this series is applied.
FYI this series is now fully acked, so I plan to apply it by the end of
this week or early next week.
> Reviewed-by: Damon Ding <[email protected]>
>
> [0]
> https://lore.kernel.org/all/20260915-drm-bridge-drm_panel-cleanup-v4-0-30401d940...@bootlin.com/
> [1] https://lore.kernel.org/all/5609825.iZASKD2KPV@diego/
Thanks for reviewing and testing!
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
