kernel: fix crash for late mipi dsi start

recipes-kernel/linux/linux-lmp-fslc-imx/portenta-x8/0001-drm-mipi-dsi-Fix-detach-call-without-attach.patch

@@ -0,0 +1,133 @@
+From 847e95abdf801b28496e7ab064ca968db3ca6876 Mon Sep 17 00:00:00 2001
+From: Tomi Valkeinen <[email protected]>
+Date: Thu, 21 Sep 2023 13:50:32 +0300
+Subject: [PATCH] drm/mipi-dsi: Fix detach call without attach
+
+It's been reported that DSI host driver's detach can be called without
+the attach ever happening:
+
+https://lore.kernel.org/all/[email protected]/
+
+After reading the code, I think this is what happens:
+
+We have a DSI host defined in the device tree and a DSI peripheral under
+that host (i.e. an i2c device using the DSI as data bus doesn't exhibit
+this behavior).
+
+The host driver calls mipi_dsi_host_register(), which causes (via a few
+functions) mipi_dsi_device_add() to be called for the DSI peripheral. So
+now we have a DSI device under the host, but attach hasn't been called.
+
+Normally the probing of the devices continues, and eventually the DSI
+peripheral's driver will call mipi_dsi_attach(), attaching the
+peripheral.
+
+However, if the host driver's probe encounters an error after calling
+mipi_dsi_host_register(), and before the peripheral has called
+mipi_dsi_attach(), the host driver will do cleanups and return an error
+from its probe function. The cleanups include calling
+mipi_dsi_host_unregister().
+
+mipi_dsi_host_unregister() will call two functions for all its DSI
+peripheral devices: mipi_dsi_detach() and mipi_dsi_device_unregister().
+The latter makes sense, as the device exists, but the former may be
+wrong as attach has not necessarily been done.
+
+To fix this, track the attached state of the peripheral, and only detach
+from mipi_dsi_host_unregister() if the peripheral was attached.
+
+Note that I have only tested this with a board with an i2c DSI
+peripheral, not with a "pure" DSI peripheral.
+
+However, slightly related, the unregister machinery still seems broken.
+E.g. if the DSI host driver is unbound, it'll detach and unregister the
+DSI peripherals. After that, when the DSI peripheral driver unbound
+it'll call detach either directly or using the devm variant, leading to
+a crash. And probably the driver will crash if it happens, for some
+reason, to try to send a message via the DSI bus.
+
+But that's another topic.
+
+Tested-by: H. Nikolaus Schaller <[email protected]>
+Acked-by: Maxime Ripard <[email protected]>
+Reviewed-by: Sebastian Reichel <[email protected]>
+Tested-by: Tony Lindgren <[email protected]>
+Signed-off-by: Tomi Valkeinen <[email protected]>
+Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
+---
+ drivers/gpu/drm/drm_mipi_dsi.c | 17 +++++++++++++++--
+ include/drm/drm_mipi_dsi.h     |  2 ++
+ 2 files changed, 17 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
+index f25ddfe37498..39eb1df76b1b 100644
+--- a/drivers/gpu/drm/drm_mipi_dsi.c
++++ b/drivers/gpu/drm/drm_mipi_dsi.c
+@@ -346,7 +346,8 @@ static int mipi_dsi_remove_device_fn(struct device *dev, void *priv)
+ {
+ 	struct mipi_dsi_device *dsi = to_mipi_dsi_device(dev);
+
+-	mipi_dsi_detach(dsi);
++	if (dsi->attached)
++		mipi_dsi_detach(dsi);
+ 	mipi_dsi_device_unregister(dsi);
+
+ 	return 0;
+@@ -369,11 +370,18 @@ EXPORT_SYMBOL(mipi_dsi_host_unregister);
+ int mipi_dsi_attach(struct mipi_dsi_device *dsi)
+ {
+ 	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
++	int ret;
+
+ 	if (!ops || !ops->attach)
+ 		return -ENOSYS;
+
+-	return ops->attach(dsi->host, dsi);
++	ret = ops->attach(dsi->host, dsi);
++	if (ret)
++		return ret;
++
++	dsi->attached = true;
++
++	return 0;
+ }
+ EXPORT_SYMBOL(mipi_dsi_attach);
+
+@@ -385,9 +393,14 @@ int mipi_dsi_detach(struct mipi_dsi_device *dsi)
+ {
+ 	const struct mipi_dsi_host_ops *ops = dsi->host->ops;
+
++	if (WARN_ON(!dsi->attached))
++		return -EINVAL;
++
+ 	if (!ops || !ops->detach)
+ 		return -ENOSYS;
+
++	dsi->attached = false;
++
+ 	return ops->detach(dsi->host, dsi);
+ }
+ EXPORT_SYMBOL(mipi_dsi_detach);
+diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
+index 9054a5185e1a..31171914990a 100644
+--- a/include/drm/drm_mipi_dsi.h
++++ b/include/drm/drm_mipi_dsi.h
+@@ -168,6 +168,7 @@ struct mipi_dsi_device_info {
+  * struct mipi_dsi_device - DSI peripheral device
+  * @host: DSI host for this peripheral
+  * @dev: driver model device node for this peripheral
++ * @attached: the DSI device has been successfully attached
+  * @name: DSI peripheral chip type
+  * @channel: virtual channel assigned to the peripheral
+  * @format: pixel format for video mode
+@@ -184,6 +185,7 @@ struct mipi_dsi_device_info {
+ struct mipi_dsi_device {
+ 	struct mipi_dsi_host *host;
+ 	struct device dev;
++	bool attached;
+
+ 	char name[DSI_DEV_NAME_SIZE];
+ 	unsigned int channel;
+-- 
+2.25.1
+

recipes-kernel/linux/linux-lmp-fslc-imx_%.bbappend

@@ -20,4 +20,5 @@ SRC_URI:append:portenta-x8 = " \
   file://QUECTEL-0001-support-ec200a.patch \
   file://DVFS-0001-Add_400MHz_200MHz_100MHz.patch \
   file://0001-spi-test.patch \
+  file://0001-drm-mipi-dsi-Fix-detach-call-without-attach.patch \
 "