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Subject[PATCH 5.15 128/262] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge
Date
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

[ Upstream commit 647474b8d980256b26b1cd112d7333a4dbd4260a ]

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@vger.kernel.org> # 5.15.x
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>
Tested-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 5d90d2eb00193..bced4c7d668e3 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;
--
2.34.1


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