Hi, Chen-yu: Chen-Yu Tsai <[email protected]> 於 2026年1月14日週三 上午9:23寫道： > > Trying to find the next bridge and deferring probe in the bridge attach > callback is much too late. At this point the driver has already finished > probing and is now running the component bind code path. What's even > worse is that in the specific case of the DSI host being the last > component to be added as part of the dsi_host_attach callback, the code > path that this is in: > > -> devm_drm_of_get_bridge() > mtk_dpi_bridge_attach() > drm_bridge_attach() > mtk_dpi_bind() > ... > component_add() > mtk_dsi_host_attach() > anx7625_attach_dsi() > anx7625_link_bridge() - done_probing callback for of_dp_aux_populate_bus() > of_dp_aux_populate_bus() > anx7625_i2c_probe() > > _cannot_ return probe defer: > > anx7625 4-0058: [drm:anx7625_bridge_attach] drm attach > mediatek-drm mediatek-drm.15.auto: bound 14014000.dsi (ops > mtk_dsi_component_ops) > mediatek-drm mediatek-drm.15.auto: error -EPROBE_DEFER: failed to attach > bridge /soc/dpi@14015000 to encoder TMDS-37 > [drm:mtk_dsi_host_attach] *ERROR* failed to add dsi_host component: -517 > anx7625 4-0058: [drm:anx7625_link_bridge] *ERROR* fail to attach dsi to > host. > panel-simple-dp-aux aux-4-0058: DP AUX done_probing() can't defer > panel-simple-dp-aux aux-4-0058: probe with driver panel-simple-dp-aux > failed with error -22 > anx7625 4-0058: [drm:anx7625_i2c_probe] probe done > > This results in the whole display driver failing to probe. > > Perhaps this was an attempt to mirror the structure in the DSI driver; > but in the DSI driver the next bridge is retrieved in the DSI attach > callback, not the bridge attach callback. > > Move the code finding the next bridge back to the probe function so that > deferred probing works correctly. Also rework the fallback to the old OF > graph endpoint numbering scheme so that deferred probing logs in both > cases. > > This issue was found on an MT8183 Jacuzzi device with an extra patch > enabling the DPI-based external display pipeline. Also tested on an > MT8192 Hayato device with both DSI and DPI display pipelines enabled.
Applied to mediatek-drm-fixes [1], thanks. [1] https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux.git/log/?h=mediatek-drm-fixes Regards, Chun-Kuang. > > Fixes: 4c932840db1d ("drm/mediatek: Implement OF graphs support for display > paths") > Signed-off-by: Chen-Yu Tsai <[email protected]> > --- > drivers/gpu/drm/mediatek/mtk_dpi.c | 23 +++++++++-------------- > 1 file changed, 9 insertions(+), 14 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dpi.c > b/drivers/gpu/drm/mediatek/mtk_dpi.c > index 61cab32e213a..53360b5d12ba 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dpi.c > +++ b/drivers/gpu/drm/mediatek/mtk_dpi.c > @@ -836,20 +836,6 @@ static int mtk_dpi_bridge_attach(struct drm_bridge > *bridge, > enum drm_bridge_attach_flags flags) > { > struct mtk_dpi *dpi = bridge_to_dpi(bridge); > - int ret; > - > - dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, > dpi->dev->of_node, 1, -1); > - if (IS_ERR(dpi->next_bridge)) { > - ret = PTR_ERR(dpi->next_bridge); > - if (ret == -EPROBE_DEFER) > - return ret; > - > - /* Old devicetree has only one endpoint */ > - dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, > dpi->dev->of_node, 0, 0); > - if (IS_ERR(dpi->next_bridge)) > - return dev_err_probe(dpi->dev, > PTR_ERR(dpi->next_bridge), > - "Failed to get bridge\n"); > - } > > return drm_bridge_attach(encoder, dpi->next_bridge, > &dpi->bridge, flags); > @@ -1319,6 +1305,15 @@ static int mtk_dpi_probe(struct platform_device *pdev) > if (dpi->irq < 0) > return dpi->irq; > > + dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, > dpi->dev->of_node, 1, -1); > + if (IS_ERR(dpi->next_bridge) && PTR_ERR(dpi->next_bridge) == -ENODEV) > { > + /* Old devicetree has only one endpoint */ > + dpi->next_bridge = devm_drm_of_get_bridge(dpi->dev, > dpi->dev->of_node, 0, 0); > + } > + if (IS_ERR(dpi->next_bridge)) > + return dev_err_probe(dpi->dev, PTR_ERR(dpi->next_bridge), > + "Failed to get bridge\n"); > + > platform_set_drvdata(pdev, dpi); > > dpi->bridge.of_node = dev->of_node; > -- > 2.52.0.457.g6b5491de43-goog >
