| Message ID | 20250407-drm-bridge-convert-to-alloc-api-v1-34-42113ff8d9c0@bootlin.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | drm: convert all bridges to devm_drm_bridge_alloc() | expand |
Hi Maxime, On Tue, 8 Apr 2025 17:51:08 +0200 Maxime Ripard <mripard@kernel.org> wrote: > Hi, > > On Mon, Apr 07, 2025 at 05:27:39PM +0200, Luca Ceresoli wrote: > > This is the new API for allocating DRM bridges. > > > > The devm lifetime management of this driver is peculiar. The underlying > > device for the panel_bridge is the panel, and the devm lifetime is tied the > > panel device (panel->dev). However the panel_bridge allocation is not > > performed by the panel driver, but rather by a separate entity (typically > > the previous bridge in the encoder chain). > > > > Thus when that separate entoty is destroyed, the panel_bridge is not > > removed automatically by devm, so it is rather done explicitly by calling > > drm_panel_bridge_remove(). This is the function that does devm_kfree() the > > panel_bridge in current code, so update it as well to put the bridge > > reference instead. > > > > Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> [...] > > --- a/drivers/gpu/drm/bridge/panel.c > > +++ b/drivers/gpu/drm/bridge/panel.c > > @@ -287,15 +287,14 @@ struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel, > > if (!panel) > > return ERR_PTR(-EINVAL); > > > > - panel_bridge = devm_kzalloc(panel->dev, sizeof(*panel_bridge), > > - GFP_KERNEL); > > - if (!panel_bridge) > > - return ERR_PTR(-ENOMEM); > > + panel_bridge = devm_drm_bridge_alloc(panel->dev, struct panel_bridge, bridge, > > + &panel_bridge_bridge_funcs); > > + if (IS_ERR(panel_bridge)) > > + return (void *)panel_bridge; > > > > panel_bridge->connector_type = connector_type; > > panel_bridge->panel = panel; > > > > - panel_bridge->bridge.funcs = &panel_bridge_bridge_funcs; > > panel_bridge->bridge.of_node = panel->dev->of_node; > > panel_bridge->bridge.ops = DRM_BRIDGE_OP_MODES; > > panel_bridge->bridge.type = connector_type; > > @@ -327,7 +326,7 @@ void drm_panel_bridge_remove(struct drm_bridge *bridge) > > panel_bridge = drm_bridge_to_panel_bridge(bridge); > > > > drm_bridge_remove(bridge); > > - devm_kfree(panel_bridge->panel->dev, bridge); > > + devm_drm_put_bridge(panel_bridge->panel->dev, bridge); > > } > > EXPORT_SYMBOL(drm_panel_bridge_remove); > > I'm fine with it on principle, but as a temporary measure. > > Now that we have the panel allocation function in place, we can just > allocate a bridge for each panel and don't need drm_panel_bridge_add_* > at all. > > As I was saying before, it doesn't need to happen right now, or before > the rest of your work for hotplug goes in. But this needs to be tackled > at some point. I totally agree this needs to be handled eventually, and also to get there in steps. The current status of this driver is not ideal, so I paid attention to not make it unnecessarily worse when writing this patch. Do you think the current patch is OK for the next step? I'm going to send v2 in a few hours, so don't hesitate to mention any improvements you deem necessary. Luca
diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c index 79b009ab9396048eac57ad47631a902e949d77c6..ddd1e91970d09b93aa64f50cd9155939a12a2c6f 100644 --- a/drivers/gpu/drm/bridge/panel.c +++ b/drivers/gpu/drm/bridge/panel.c @@ -287,15 +287,14 @@ struct drm_bridge *drm_panel_bridge_add_typed(struct drm_panel *panel, if (!panel) return ERR_PTR(-EINVAL); - panel_bridge = devm_kzalloc(panel->dev, sizeof(*panel_bridge), - GFP_KERNEL); - if (!panel_bridge) - return ERR_PTR(-ENOMEM); + panel_bridge = devm_drm_bridge_alloc(panel->dev, struct panel_bridge, bridge, + &panel_bridge_bridge_funcs); + if (IS_ERR(panel_bridge)) + return (void *)panel_bridge; panel_bridge->connector_type = connector_type; panel_bridge->panel = panel; - panel_bridge->bridge.funcs = &panel_bridge_bridge_funcs; panel_bridge->bridge.of_node = panel->dev->of_node; panel_bridge->bridge.ops = DRM_BRIDGE_OP_MODES; panel_bridge->bridge.type = connector_type; @@ -327,7 +326,7 @@ void drm_panel_bridge_remove(struct drm_bridge *bridge) panel_bridge = drm_bridge_to_panel_bridge(bridge); drm_bridge_remove(bridge); - devm_kfree(panel_bridge->panel->dev, bridge); + devm_drm_put_bridge(panel_bridge->panel->dev, bridge); } EXPORT_SYMBOL(drm_panel_bridge_remove);
This is the new API for allocating DRM bridges. The devm lifetime management of this driver is peculiar. The underlying device for the panel_bridge is the panel, and the devm lifetime is tied the panel device (panel->dev). However the panel_bridge allocation is not performed by the panel driver, but rather by a separate entity (typically the previous bridge in the encoder chain). Thus when that separate entoty is destroyed, the panel_bridge is not removed automatically by devm, so it is rather done explicitly by calling drm_panel_bridge_remove(). This is the function that does devm_kfree() the panel_bridge in current code, so update it as well to put the bridge reference instead. Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com> --- To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> To: Maxime Ripard <mripard@kernel.org> To: Thomas Zimmermann <tzimmermann@suse.de> To: David Airlie <airlied@gmail.com> To: Simona Vetter <simona@ffwll.ch> To: Andrzej Hajda <andrzej.hajda@intel.com> To: Neil Armstrong <neil.armstrong@linaro.org> To: Robert Foss <rfoss@kernel.org> To: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> To: Jonas Karlman <jonas@kwiboo.se> To: Jernej Skrabec <jernej.skrabec@gmail.com> To: Jagan Teki <jagan@amarulasolutions.com> To: Shawn Guo <shawnguo@kernel.org> To: Sascha Hauer <s.hauer@pengutronix.de> To: Pengutronix Kernel Team <kernel@pengutronix.de> To: Fabio Estevam <festevam@gmail.com> To: Douglas Anderson <dianders@chromium.org> To: Chun-Kuang Hu <chunkuang.hu@kernel.org> To: Krzysztof Kozlowski <krzk@kernel.org> To: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Cc: Anusha Srivatsa <asrivats@redhat.com> Cc: Paul Kocialkowski <paulk@sys-base.io> Cc: Dmitry Baryshkov <lumag@kernel.org> Cc: Hervé Codina <herve.codina@bootlin.com> Cc: Hui Pu <Hui.Pu@gehealthcare.com> Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com> Cc: dri-devel@lists.freedesktop.org Cc: asahi@lists.linux.dev Cc: linux-kernel@vger.kernel.org Cc: chrome-platform@lists.linux.dev Cc: imx@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org Cc: linux-mediatek@lists.infradead.org Cc: linux-amlogic@lists.infradead.org Cc: linux-renesas-soc@vger.kernel.org Cc: platform-driver-x86@vger.kernel.org Cc: linux-samsung-soc@vger.kernel.org Cc: linux-arm-msm@vger.kernel.org Cc: freedreno@lists.freedesktop.org Cc: linux-stm32@st-md-mailman.stormreply.com --- drivers/gpu/drm/bridge/panel.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)