| Message ID | 20220127143623.123025-1-angelogioacchino.delregno@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge | expand |
Hi, Angelo: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於 2022年1月27日 週四 下午10:36寫道： > > 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). > > Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges") The fixed tag should indicate the patch which cause the bug, but why a patch just adding document would cause bug? So no any patch cause bug? This patch just want to prevent a possible bug? Regards, Chun-Kuang. > Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> > Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> > Reviewed-by: Jagan Teki <jagan@amarulasolutions.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); > } > > +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) > +{ > + int ret; > + > + ret = drm_simple_encoder_init(drm, &dsi->encoder, > + DRM_MODE_ENCODER_DSI); > + if (ret) { > + DRM_ERROR("Failed to encoder init to drm\n"); > + return ret; > + } > + > + dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); > + > + ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, > + DRM_BRIDGE_ATTACH_NO_CONNECTOR); > + if (ret) > + goto err_cleanup_encoder; > + > + dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); > + if (IS_ERR(dsi->connector)) { > + DRM_ERROR("Unable to create bridge connector\n"); > + ret = PTR_ERR(dsi->connector); > + goto err_cleanup_encoder; > + } > + drm_connector_attach_encoder(dsi->connector, &dsi->encoder); > + > + return 0; > + > +err_cleanup_encoder: > + drm_encoder_cleanup(&dsi->encoder); > + return ret; > +} > + > +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) > +{ > + int ret; > + struct drm_device *drm = data; > + struct mtk_dsi *dsi = dev_get_drvdata(dev); > + > + ret = mtk_dsi_encoder_init(drm, dsi); > + if (ret) > + return ret; > + > + return device_reset_optional(dev); > +} > + > +static void mtk_dsi_unbind(struct device *dev, struct device *master, > + void *data) > +{ > + struct mtk_dsi *dsi = dev_get_drvdata(dev); > + > + drm_encoder_cleanup(&dsi->encoder); > +} > + > +static const struct component_ops mtk_dsi_component_ops = { > + .bind = mtk_dsi_bind, > + .unbind = mtk_dsi_unbind, > +}; > + > 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); > + 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, > }; > > -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) > -{ > - int ret; > - > - ret = drm_simple_encoder_init(drm, &dsi->encoder, > - DRM_MODE_ENCODER_DSI); > - if (ret) { > - DRM_ERROR("Failed to encoder init to drm\n"); > - return ret; > - } > - > - dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); > - > - ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, > - DRM_BRIDGE_ATTACH_NO_CONNECTOR); > - if (ret) > - goto err_cleanup_encoder; > - > - dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); > - if (IS_ERR(dsi->connector)) { > - DRM_ERROR("Unable to create bridge connector\n"); > - ret = PTR_ERR(dsi->connector); > - goto err_cleanup_encoder; > - } > - drm_connector_attach_encoder(dsi->connector, &dsi->encoder); > - > - return 0; > - > -err_cleanup_encoder: > - drm_encoder_cleanup(&dsi->encoder); > - return ret; > -} > - > -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) > -{ > - int ret; > - struct drm_device *drm = data; > - struct mtk_dsi *dsi = dev_get_drvdata(dev); > - > - ret = mtk_dsi_encoder_init(drm, dsi); > - if (ret) > - return ret; > - > - return device_reset_optional(dev); > -} > - > -static void mtk_dsi_unbind(struct device *dev, struct device *master, > - void *data) > -{ > - struct mtk_dsi *dsi = dev_get_drvdata(dev); > - > - drm_encoder_cleanup(&dsi->encoder); > -} > - > -static const struct component_ops mtk_dsi_component_ops = { > - .bind = mtk_dsi_bind, > - .unbind = mtk_dsi_unbind, > -}; > - > 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; > -- > 2.33.1 >
Il 27/01/22 16:21, Chun-Kuang Hu ha scritto: > Hi, Angelo: > > AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於 > 2022年1月27日 週四 下午10:36寫道： >> >> 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). >> >> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges") > > The fixed tag should indicate the patch which cause the bug, but why a > patch just adding document would cause bug? > So no any patch cause bug? This patch just want to prevent a possible bug? > I think you've missed my previous message on v2, so I will paste it here: unfortunately I couldn't find a valid commit for a Fixes tag. This started being an issue at some point, when the DRM was changed to adhere to the documented probe sequence: the MediaTek DSI driver was not the only one that got broken/affected by these changes. If you have any advice on which commit should be tagged, I'm open for any kind of suggestion. I tried to check on other drivers which got fixed for the same behavior, for example drm/msm, but none of them had a Fixes tag. When the DRM got changed to adhere to this sequence, some drm/bridge drivers were also changed; this has created some incompatibilities with some drm drivers, including drm/msm and drm/mediatek. This commit is not fixing a latent bug that was introduced in drm/mediatek but rather one that was induced by the new, fixed, probe flow that got recently documented - and to which drivers should adhere; failing to adhere to that will produce an endless -EPROBE_DEFER loop, due to other drivers (as mentioned, for example drm/bridge drivers) having been changed to use that probe sequence. Regards, Angelo > Regards, > Chun-Kuang. > >> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> >> Reviewed-by: Jagan Teki <jagan@amarulasolutions.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); >> } >> >> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) >> +{ >> + int ret; >> + >> + ret = drm_simple_encoder_init(drm, &dsi->encoder, >> + DRM_MODE_ENCODER_DSI); >> + if (ret) { >> + DRM_ERROR("Failed to encoder init to drm\n"); >> + return ret; >> + } >> + >> + dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); >> + >> + ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, >> + DRM_BRIDGE_ATTACH_NO_CONNECTOR); >> + if (ret) >> + goto err_cleanup_encoder; >> + >> + dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); >> + if (IS_ERR(dsi->connector)) { >> + DRM_ERROR("Unable to create bridge connector\n"); >> + ret = PTR_ERR(dsi->connector); >> + goto err_cleanup_encoder; >> + } >> + drm_connector_attach_encoder(dsi->connector, &dsi->encoder); >> + >> + return 0; >> + >> +err_cleanup_encoder: >> + drm_encoder_cleanup(&dsi->encoder); >> + return ret; >> +} >> + >> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) >> +{ >> + int ret; >> + struct drm_device *drm = data; >> + struct mtk_dsi *dsi = dev_get_drvdata(dev); >> + >> + ret = mtk_dsi_encoder_init(drm, dsi); >> + if (ret) >> + return ret; >> + >> + return device_reset_optional(dev); >> +} >> + >> +static void mtk_dsi_unbind(struct device *dev, struct device *master, >> + void *data) >> +{ >> + struct mtk_dsi *dsi = dev_get_drvdata(dev); >> + >> + drm_encoder_cleanup(&dsi->encoder); >> +} >> + >> +static const struct component_ops mtk_dsi_component_ops = { >> + .bind = mtk_dsi_bind, >> + .unbind = mtk_dsi_unbind, >> +}; >> + >> 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); >> + 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, >> }; >> >> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) >> -{ >> - int ret; >> - >> - ret = drm_simple_encoder_init(drm, &dsi->encoder, >> - DRM_MODE_ENCODER_DSI); >> - if (ret) { >> - DRM_ERROR("Failed to encoder init to drm\n"); >> - return ret; >> - } >> - >> - dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); >> - >> - ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, >> - DRM_BRIDGE_ATTACH_NO_CONNECTOR); >> - if (ret) >> - goto err_cleanup_encoder; >> - >> - dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); >> - if (IS_ERR(dsi->connector)) { >> - DRM_ERROR("Unable to create bridge connector\n"); >> - ret = PTR_ERR(dsi->connector); >> - goto err_cleanup_encoder; >> - } >> - drm_connector_attach_encoder(dsi->connector, &dsi->encoder); >> - >> - return 0; >> - >> -err_cleanup_encoder: >> - drm_encoder_cleanup(&dsi->encoder); >> - return ret; >> -} >> - >> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) >> -{ >> - int ret; >> - struct drm_device *drm = data; >> - struct mtk_dsi *dsi = dev_get_drvdata(dev); >> - >> - ret = mtk_dsi_encoder_init(drm, dsi); >> - if (ret) >> - return ret; >> - >> - return device_reset_optional(dev); >> -} >> - >> -static void mtk_dsi_unbind(struct device *dev, struct device *master, >> - void *data) >> -{ >> - struct mtk_dsi *dsi = dev_get_drvdata(dev); >> - >> - drm_encoder_cleanup(&dsi->encoder); >> -} >> - >> -static const struct component_ops mtk_dsi_component_ops = { >> - .bind = mtk_dsi_bind, >> - .unbind = mtk_dsi_unbind, >> -}; >> - >> 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; >> -- >> 2.33.1 >>
Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto: > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto: >> Hi, Angelo: >> >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於 >> 2022年1月27日 週四 下午10:36寫道： >>> >>> 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). >>> >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges") >> >> The fixed tag should indicate the patch which cause the bug, but why a >> patch just adding document would cause bug? >> So no any patch cause bug? This patch just want to prevent a possible bug? >> > > I think you've missed my previous message on v2, so I will paste it here: > > unfortunately I couldn't find a valid commit for a Fixes tag. This > started being an issue at some point, when the DRM was changed to > adhere to the documented probe sequence: the MediaTek DSI driver was > not the only one that got broken/affected by these changes. > > If you have any advice on which commit should be tagged, I'm open for > any kind of suggestion. > > > I tried to check on other drivers which got fixed for the same behavior, > for example drm/msm, but none of them had a Fixes tag. > When the DRM got changed to adhere to this sequence, some drm/bridge > drivers were also changed; this has created some incompatibilities with > some drm drivers, including drm/msm and drm/mediatek. > > This commit is not fixing a latent bug that was introduced in drm/mediatek > but rather one that was induced by the new, fixed, probe flow that got > recently documented - and to which drivers should adhere; failing to adhere > to that will produce an endless -EPROBE_DEFER loop, due to other drivers > (as mentioned, for example drm/bridge drivers) having been changed to use > that probe sequence. > > > Regards, > Angelo > I've been thinking about another solution to this issue. Would it be fine if I send a v4 that removes the Fixes tag, but adds the following? Cc: stable@kernel.org # v5.15+ >> Regards, >> Chun-Kuang. >> >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com> >>> >>> --- >>> drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++-------------- >>> 1 file changed, 84 insertions(+), 83 deletions(-) >>>
AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於 2022年1月28日 週五 下午5:13寫道： > > Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto: > > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto: > >> Hi, Angelo: > >> > >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於 > >> 2022年1月27日 週四 下午10:36寫道： > >>> > >>> 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). > >>> > >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges") > >> > >> The fixed tag should indicate the patch which cause the bug, but why a > >> patch just adding document would cause bug? > >> So no any patch cause bug? This patch just want to prevent a possible bug? > >> > > > > I think you've missed my previous message on v2, so I will paste it here: > > > > unfortunately I couldn't find a valid commit for a Fixes tag. This > > started being an issue at some point, when the DRM was changed to > > adhere to the documented probe sequence: the MediaTek DSI driver was > > not the only one that got broken/affected by these changes. > > > > If you have any advice on which commit should be tagged, I'm open for > > any kind of suggestion. > > > > > > I tried to check on other drivers which got fixed for the same behavior, > > for example drm/msm, but none of them had a Fixes tag. > > When the DRM got changed to adhere to this sequence, some drm/bridge > > drivers were also changed; this has created some incompatibilities with > > some drm drivers, including drm/msm and drm/mediatek. > > > > This commit is not fixing a latent bug that was introduced in drm/mediatek > > but rather one that was induced by the new, fixed, probe flow that got > > recently documented - and to which drivers should adhere; failing to adhere > > to that will produce an endless -EPROBE_DEFER loop, due to other drivers > > (as mentioned, for example drm/bridge drivers) having been changed to use > > that probe sequence. > > > > > > Regards, > > Angelo > > > > I've been thinking about another solution to this issue. > > Would it be fine if I send a v4 that removes the Fixes tag, but adds the following? > > Cc: stable@kernel.org # v5.15+ It's ok to me. According to the documented format [1], I think this should be Cc: <stable@vger.kernel.org> # 5.15.x [1] https://www.kernel.org/doc/html/v5.16/process/stable-kernel-rules.html Regards, Chun-Kuang. > > >> Regards, > >> Chun-Kuang. > >> > >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> > >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> > >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com> > >>> > >>> --- > >>> drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++-------------- > >>> 1 file changed, 84 insertions(+), 83 deletions(-) > >>> > > > -- > AngeloGioacchino Del Regno > Software Engineer > > Collabora Ltd. > Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK > Registered in England & Wales, no. 5513718
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); } +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) +{ + int ret; + + ret = drm_simple_encoder_init(drm, &dsi->encoder, + DRM_MODE_ENCODER_DSI); + if (ret) { + DRM_ERROR("Failed to encoder init to drm\n"); + return ret; + } + + dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); + + ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, + DRM_BRIDGE_ATTACH_NO_CONNECTOR); + if (ret) + goto err_cleanup_encoder; + + dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); + if (IS_ERR(dsi->connector)) { + DRM_ERROR("Unable to create bridge connector\n"); + ret = PTR_ERR(dsi->connector); + goto err_cleanup_encoder; + } + drm_connector_attach_encoder(dsi->connector, &dsi->encoder); + + return 0; + +err_cleanup_encoder: + drm_encoder_cleanup(&dsi->encoder); + return ret; +} + +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) +{ + int ret; + struct drm_device *drm = data; + struct mtk_dsi *dsi = dev_get_drvdata(dev); + + ret = mtk_dsi_encoder_init(drm, dsi); + if (ret) + return ret; + + return device_reset_optional(dev); +} + +static void mtk_dsi_unbind(struct device *dev, struct device *master, + void *data) +{ + struct mtk_dsi *dsi = dev_get_drvdata(dev); + + drm_encoder_cleanup(&dsi->encoder); +} + +static const struct component_ops mtk_dsi_component_ops = { + .bind = mtk_dsi_bind, + .unbind = mtk_dsi_unbind, +}; + 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); + 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, }; -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi) -{ - int ret; - - ret = drm_simple_encoder_init(drm, &dsi->encoder, - DRM_MODE_ENCODER_DSI); - if (ret) { - DRM_ERROR("Failed to encoder init to drm\n"); - return ret; - } - - dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev); - - ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL, - DRM_BRIDGE_ATTACH_NO_CONNECTOR); - if (ret) - goto err_cleanup_encoder; - - dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder); - if (IS_ERR(dsi->connector)) { - DRM_ERROR("Unable to create bridge connector\n"); - ret = PTR_ERR(dsi->connector); - goto err_cleanup_encoder; - } - drm_connector_attach_encoder(dsi->connector, &dsi->encoder); - - return 0; - -err_cleanup_encoder: - drm_encoder_cleanup(&dsi->encoder); - return ret; -} - -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data) -{ - int ret; - struct drm_device *drm = data; - struct mtk_dsi *dsi = dev_get_drvdata(dev); - - ret = mtk_dsi_encoder_init(drm, dsi); - if (ret) - return ret; - - return device_reset_optional(dev); -} - -static void mtk_dsi_unbind(struct device *dev, struct device *master, - void *data) -{ - struct mtk_dsi *dsi = dev_get_drvdata(dev); - - drm_encoder_cleanup(&dsi->encoder); -} - -static const struct component_ops mtk_dsi_component_ops = { - .bind = mtk_dsi_bind, - .unbind = mtk_dsi_unbind, -}; - 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;
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). Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges") Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com> --- drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++-------------- 1 file changed, 84 insertions(+), 83 deletions(-)