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 <[email protected]>
Reviewed-by: Andrzej Hajda <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>
---
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
Hi, Angelo:
AngeloGioacchino Del Regno <[email protected]> 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 <[email protected]>
> Reviewed-by: Andrzej Hajda <[email protected]>
> Reviewed-by: Jagan Teki <[email protected]>
>
> ---
> 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 <[email protected]> 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 <[email protected]>
>> Reviewed-by: Andrzej Hajda <[email protected]>
>> Reviewed-by: Jagan Teki <[email protected]>
>>
>> ---
>> 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
>>
--
AngeloGioacchino Del Regno
Software Engineer
Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718
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 <[email protected]> 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: [email protected] # v5.15+
>> Regards,
>> Chun-Kuang.
>>
>>> Signed-off-by: AngeloGioacchino Del Regno <[email protected]>
>>> Reviewed-by: Andrzej Hajda <[email protected]>
>>> Reviewed-by: Jagan Teki <[email protected]>
>>>
>>> ---
>>> 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
AngeloGioacchino Del Regno <[email protected]> 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 <[email protected]> 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: [email protected] # v5.15+
It's ok to me. According to the documented format [1], I think this should be
Cc: <[email protected]> # 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 <[email protected]>
> >>> Reviewed-by: Andrzej Hajda <[email protected]>
> >>> Reviewed-by: Jagan Teki <[email protected]>
> >>>
> >>> ---
> >>> 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