linux-kernel - Re: [PATCH v2 27/34] drm/vc4: convert to devm_drm_bridge

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Message-ID: <CAPY8ntDwK0DZ6sThryDRBUgjTb+muNHtRNp+LohTs6+FWeB5TQ@mail.gmail.com>
Date: Mon, 28 Apr 2025 16:45:08 +0100
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Andrzej Hajda <andrzej.hajda@...el.com>, Neil Armstrong <neil.armstrong@...aro.org>, 
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	Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
	Jagan Teki <jagan@...rulasolutions.com>, Shawn Guo <shawnguo@...nel.org>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Pengutronix Kernel Team <kernel@...gutronix.de>, 
	Fabio Estevam <festevam@...il.com>, Douglas Anderson <dianders@...omium.org>, 
	Chun-Kuang Hu <chunkuang.hu@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>, 
	Anusha Srivatsa <asrivats@...hat.com>, Paul Kocialkowski <paulk@...-base.io>, 
	Dmitry Baryshkov <lumag@...nel.org>, Hui Pu <Hui.Pu@...ealthcare.com>, 
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>, dri-devel@...ts.freedesktop.org, 
	asahi@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	chrome-platform@...ts.linux.dev, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-mediatek@...ts.infradead.org, 
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	linux-stm32@...md-mailman.stormreply.com, Maíra Canal <mcanal@...lia.com>, 
	Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>
Subject: Re: [PATCH v2 27/34] drm/vc4: convert to devm_drm_bridge_alloc() API

On Thu, 24 Apr 2025 at 20:01, Luca Ceresoli <luca.ceresoli@...tlin.com> wrote:
>
> This is the new API for allocating DRM bridges.
>
> This driver already implements refcounting of the struct vc4_dsi, which
> embeds struct drm_bridge. Now this is a duplicate of the refcounting
> implemented by the DRM bridge core, so convert the vc4_dsi_get/put() calls
> into drm_bridge_get/put() calls and get rid of the driver-specific
> refcounting implementation.
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

Acked-by: Dave Stevenson <dave.stevenson@...pberrypi.com>

Thanks.

> ---
>
> Cc: "Maíra Canal" <mcanal@...lia.com>
> Cc: Dave Stevenson <dave.stevenson@...pberrypi.com>
> Cc: Raspberry Pi Kernel Maintenance <kernel-list@...pberrypi.com>
>
> Changed in v2:
> - fix error code checking
> ---
>  drivers/gpu/drm/vc4/vc4_dsi.c | 34 +++++-----------------------------
>  1 file changed, 5 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
> index efc6f6078b026764c59cfb2a33b28a88b7018c3a..458e5d9879645f18bcbcaeeb71b5f1038f9581da 100644
> --- a/drivers/gpu/drm/vc4/vc4_dsi.c
> +++ b/drivers/gpu/drm/vc4/vc4_dsi.c
> @@ -552,8 +552,6 @@ struct vc4_dsi {
>         struct vc4_encoder encoder;
>         struct mipi_dsi_host dsi_host;
>
> -       struct kref kref;
> -
>         struct platform_device *pdev;
>
>         struct drm_bridge *out_bridge;
> @@ -1622,29 +1620,11 @@ static void vc4_dsi_dma_chan_release(void *ptr)
>         dsi->reg_dma_chan = NULL;
>  }
>
> -static void vc4_dsi_release(struct kref *kref)
> -{
> -       struct vc4_dsi *dsi =
> -               container_of(kref, struct vc4_dsi, kref);
> -
> -       kfree(dsi);
> -}
> -
> -static void vc4_dsi_get(struct vc4_dsi *dsi)
> -{
> -       kref_get(&dsi->kref);
> -}
> -
> -static void vc4_dsi_put(struct vc4_dsi *dsi)
> -{
> -       kref_put(&dsi->kref, &vc4_dsi_release);
> -}
> -
>  static void vc4_dsi_release_action(struct drm_device *drm, void *ptr)
>  {
>         struct vc4_dsi *dsi = ptr;
>
> -       vc4_dsi_put(dsi);
> +       drm_bridge_put(&dsi->bridge);
>  }
>
>  static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
> @@ -1655,7 +1635,7 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
>         struct drm_encoder *encoder = &dsi->encoder.base;
>         int ret;
>
> -       vc4_dsi_get(dsi);
> +       drm_bridge_get(&dsi->bridge);
>
>         ret = drmm_add_action_or_reset(drm, vc4_dsi_release_action, dsi);
>         if (ret)
> @@ -1810,15 +1790,12 @@ static int vc4_dsi_dev_probe(struct platform_device *pdev)
>         struct device *dev = &pdev->dev;
>         struct vc4_dsi *dsi;
>
> -       dsi = kzalloc(sizeof(*dsi), GFP_KERNEL);
> -       if (!dsi)
> -               return -ENOMEM;
> +       dsi = devm_drm_bridge_alloc(&pdev->dev, struct vc4_dsi, bridge, &vc4_dsi_bridge_funcs);
> +       if (IS_ERR(dsi))
> +               return PTR_ERR(dsi);
>         dev_set_drvdata(dev, dsi);
>
> -       kref_init(&dsi->kref);
> -
>         dsi->pdev = pdev;
> -       dsi->bridge.funcs = &vc4_dsi_bridge_funcs;
>  #ifdef CONFIG_OF
>         dsi->bridge.of_node = dev->of_node;
>  #endif
> @@ -1836,7 +1813,6 @@ static void vc4_dsi_dev_remove(struct platform_device *pdev)
>         struct vc4_dsi *dsi = dev_get_drvdata(dev);
>
>         mipi_dsi_host_unregister(&dsi->dsi_host);
> -       vc4_dsi_put(dsi);
>  }
>
>  struct platform_driver vc4_dsi_driver = {
>
> --
> 2.49.0
>