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Message-ID: <20755168cc2be0d1bb5e40907cfe27cea25a9363.camel@mediatek.com> Date: Tue, 8 Feb 2022 16:20:58 +0800 From: CK Hu <ck.hu@...iatek.com> To: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>, <dri-devel@...ts.freedesktop.org> CC: <chunkuang.hu@...nel.org>, <airlied@...ux.ie>, <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>, <andrzej.hajda@...el.com>, <linux-mediatek@...ts.infradead.org>, Jagan Teki <jagan@...rulasolutions.com>, <matthias.bgg@...il.com>, <kernel@...labora.com>, <linux-arm-kernel@...ts.infradead.org> Subject: Re: [PATCH v4] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge Hi, Angelo: On Mon, 2022-01-31 at 09:55 +0100, AngeloGioacchino Del Regno wrote: > DRM bridge drivers are now attaching their DSI device at probe time, > which requires us to register our DSI host in order to let the bridge > to probe: this recently started producing an endless -EPROBE_DEFER > loop on some machines that are using external bridges, like the > parade-ps8640, found on the ACER Chromebook R13. > > Now that the DSI hosts/devices probe sequence is documented, we can > do adjustments to the mtk_dsi driver as to both fix now and make sure > to avoid this situation in the future: for this, following what is > documented in drm_bridge.c, move the mtk_dsi component_add() to the > mtk_dsi_ops.attach callback and delete it in the detach callback; > keeping in mind that we are registering a drm_bridge for our DSI, > which is only used/attached if the DSI Host is bound, it wouldn't > make sense to keep adding our bridge at probe time (as it would > be useless to have it if mtk_dsi_ops.attach() fails!), so also move > that one to the dsi host attach function (and remove it in detach). > > Cc: <stable@...r.kernel.org> # 5.15.x > Signed-off-by: AngeloGioacchino Del Regno < > angelogioacchino.delregno@...labora.com> > Reviewed-by: Andrzej Hajda <andrzej.hajda@...el.com> > Reviewed-by: Jagan Teki <jagan@...rulasolutions.com> > > --- > drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++---------- > ---- > 1 file changed, 84 insertions(+), 83 deletions(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c > b/drivers/gpu/drm/mediatek/mtk_dsi.c > index 5d90d2eb0019..bced4c7d668e 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dsi.c > +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c > @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev) > mtk_dsi_poweroff(dsi); > } > > [snip] > + > static int mtk_dsi_host_attach(struct mipi_dsi_host *host, > struct mipi_dsi_device *device) > { > struct mtk_dsi *dsi = host_to_dsi(host); > + struct device *dev = host->dev; > + int ret; > > dsi->lanes = device->lanes; > dsi->format = device->format; > dsi->mode_flags = device->mode_flags; > + dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, > 0); The original would process panel. Why do you remove the panel part? It's better that someone has a platform of DSI->Panel to test this patch. Regards, CK > + if (IS_ERR(dsi->next_bridge)) > + return PTR_ERR(dsi->next_bridge); > + > + drm_bridge_add(&dsi->bridge); > + > + ret = component_add(host->dev, &mtk_dsi_component_ops); > + if (ret) { > + DRM_ERROR("failed to add dsi_host component: %d\n", > ret); > + drm_bridge_remove(&dsi->bridge); > + return ret; > + } > > return 0; > } > > +static int mtk_dsi_host_detach(struct mipi_dsi_host *host, > + struct mipi_dsi_device *device) > +{ > + struct mtk_dsi *dsi = host_to_dsi(host); > + > + component_del(host->dev, &mtk_dsi_component_ops); > + drm_bridge_remove(&dsi->bridge); > + return 0; > +} > + > static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi) > { > int ret; > @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct > mipi_dsi_host *host, > > static const struct mipi_dsi_host_ops mtk_dsi_ops = { > .attach = mtk_dsi_host_attach, > + .detach = mtk_dsi_host_detach, > .transfer = mtk_dsi_host_transfer, > }; > > [snip] > - > static int mtk_dsi_probe(struct platform_device *pdev) > { > struct mtk_dsi *dsi; > struct device *dev = &pdev->dev; > - struct drm_panel *panel; > struct resource *regs; > int irq_num; > int ret; > @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct > platform_device *pdev) > return ret; > } > > - ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0, > - &panel, &dsi->next_bridge); > - if (ret) > - goto err_unregister_host; > - > - if (panel) { > - dsi->next_bridge = devm_drm_panel_bridge_add(dev, > panel); > - if (IS_ERR(dsi->next_bridge)) { > - ret = PTR_ERR(dsi->next_bridge); > - goto err_unregister_host; > - } > - } > - > dsi->driver_data = of_device_get_match_data(dev); > > dsi->engine_clk = devm_clk_get(dev, "engine"); > @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct > platform_device *pdev) > dsi->bridge.of_node = dev->of_node; > dsi->bridge.type = DRM_MODE_CONNECTOR_DSI; > > - drm_bridge_add(&dsi->bridge); > - > - ret = component_add(&pdev->dev, &mtk_dsi_component_ops); > - if (ret) { > - dev_err(&pdev->dev, "failed to add component: %d\n", > ret); > - goto err_unregister_host; > - } > - > return 0; > > err_unregister_host: > @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct > platform_device *pdev) > struct mtk_dsi *dsi = platform_get_drvdata(pdev); > > mtk_output_dsi_disable(dsi); > - drm_bridge_remove(&dsi->bridge); > - component_del(&pdev->dev, &mtk_dsi_component_ops); > mipi_dsi_host_unregister(&dsi->host); > > return 0;
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