[v3] drm/bridge: add of_drm_find_and_get_bridge() and a managed *next_bridge, deprecate of_drm_find_bridge()

[PATCH v3 12/22] drm/meson: encoder_hdmi: get/put the next bridge

Posted by Luca Ceresoli 1 month, 3 weeks ago

This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
function and stores it until driver removal. of_drm_find_bridge() is
deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
refcounted and use bridge->next_bridge to put the reference on
deallocation.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
---
 drivers/gpu/drm/meson/meson_encoder_hdmi.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_encoder_hdmi.c b/drivers/gpu/drm/meson/meson_encoder_hdmi.c
index 8205ee56a691..dc4e23590a6e 100644
--- a/drivers/gpu/drm/meson/meson_encoder_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_encoder_hdmi.c
@@ -38,7 +38,6 @@
 struct meson_encoder_hdmi {
 	struct drm_encoder encoder;
 	struct drm_bridge bridge;
-	struct drm_bridge *next_bridge;
 	struct drm_connector *connector;
 	struct meson_drm *priv;
 	unsigned long output_bus_fmt;
@@ -54,7 +53,7 @@ static int meson_encoder_hdmi_attach(struct drm_bridge *bridge,
 {
 	struct meson_encoder_hdmi *encoder_hdmi = bridge_to_meson_encoder_hdmi(bridge);
 
-	return drm_bridge_attach(encoder, encoder_hdmi->next_bridge,
+	return drm_bridge_attach(encoder, encoder_hdmi->bridge.next_bridge,
 				 &encoder_hdmi->bridge, flags);
 }
 
@@ -334,7 +333,7 @@ static void meson_encoder_hdmi_hpd_notify(struct drm_bridge *bridge,
 		const struct drm_edid *drm_edid;
 		const struct edid *edid;
 
-		drm_edid = drm_bridge_edid_read(encoder_hdmi->next_bridge,
+		drm_edid = drm_bridge_edid_read(encoder_hdmi->bridge.next_bridge,
 						encoder_hdmi->connector);
 		if (!drm_edid)
 			return;
@@ -390,8 +389,8 @@ int meson_encoder_hdmi_probe(struct meson_drm *priv)
 		return 0;
 	}
 
-	meson_encoder_hdmi->next_bridge = of_drm_find_bridge(remote);
-	if (!meson_encoder_hdmi->next_bridge) {
+	meson_encoder_hdmi->bridge.next_bridge = of_drm_find_and_get_bridge(remote);
+	if (!meson_encoder_hdmi->bridge.next_bridge) {
 		ret = dev_err_probe(priv->dev, -EPROBE_DEFER,
 				    "Failed to find HDMI transceiver bridge\n");
 		goto err_put_node;

-- 
2.52.0

Re: [PATCH v3 12/22] drm/meson: encoder_hdmi: get/put the next bridge

Posted by Martin Blumenstingl 1 month, 2 weeks ago

On Tue, Dec 16, 2025 at 7:00 PM Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
>
> This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
> function and stores it until driver removal. of_drm_find_bridge() is
> deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
> refcounted and use bridge->next_bridge to put the reference on
> deallocation.
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
And additionally I runtime tested this on meson-gxl-s905x-libretech-cc
where I still have HDMI output, so:
Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Re: [PATCH v3 12/22] drm/meson: encoder_hdmi: get/put the next bridge

Posted by Luca Ceresoli 1 month, 2 weeks ago

Hello Martin,

On Sun Dec 21, 2025 at 10:51 PM CET, Martin Blumenstingl wrote:
> On Tue, Dec 16, 2025 at 7:00 PM Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
>>
>> This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
>> function and stores it until driver removal. of_drm_find_bridge() is
>> deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
>> refcounted and use bridge->next_bridge to put the reference on
>> deallocation.
>>
>> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> And additionally I runtime tested this on meson-gxl-s905x-libretech-cc
> where I still have HDMI output, so:
> Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Thank you for the quick testing!

I think I can append '# meson-gxl-s905x-libretech-cc' to your 'Tested-by:'
line when I'll apply the patch, to make it more informative.

Best regards,
Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH v3 12/22] drm/meson: encoder_hdmi: get/put the next bridge

Posted by Martin Blumenstingl 1 month, 2 weeks ago

Hi Luca,

On Mon, Dec 22, 2025 at 8:31 AM Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
>
> Hello Martin,
>
> On Sun Dec 21, 2025 at 10:51 PM CET, Martin Blumenstingl wrote:
> > On Tue, Dec 16, 2025 at 7:00 PM Luca Ceresoli <luca.ceresoli@bootlin.com> wrote:
> >>
> >> This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
> >> function and stores it until driver removal. of_drm_find_bridge() is
> >> deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
> >> refcounted and use bridge->next_bridge to put the reference on
> >> deallocation.
> >>
> >> Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
> > Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
> > And additionally I runtime tested this on meson-gxl-s905x-libretech-cc
> > where I still have HDMI output, so:
> > Tested-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
>
> Thank you for the quick testing!
Thank you for doing the hard work ;-)

> I think I can append '# meson-gxl-s905x-libretech-cc' to your 'Tested-by:'
> line when I'll apply the patch, to make it more informative.
Sure, please go ahead with that!


Best regards,
Martin

Re: [PATCH v3 12/22] drm/meson: encoder_hdmi: get/put the next bridge

Posted by Maxime Ripard 1 month, 3 weeks ago

On Tue, 16 Dec 2025 18:58:45 +0100, Luca Ceresoli wrote:
> This driver obtains a bridge pointer from of_drm_find_bridge() in the probe
> function and stores it until driver removal. of_drm_find_bridge() is
> deprecated. Move to of_drm_find_and_get_bridge() for the bridge to be
> refcounted and use bridge->next_bridge to put the reference on
> deallocation.
> 
> [ ... ]

Reviewed-by: Maxime Ripard <mripard@kernel.org>

Thanks!
Maxime