[PATCH v5 1/9] drm: Add a vendor-specific recovery method to device wedged uevent

[Riana Tauro]

This patch addresses the need for a recovery method (firmware-update
on Firmware errors) introduced in the later patches of Xe KMD. Whenever
XE KMD detects a firmware error, a drm wedged uevent needs to be sent
to the system administrator/userspace to trigger a firmware update.

The initial proposal to use 'firmware-flash' as a recovery method was
not applicable to other drivers and could cause multiple recovery
methods specific to vendors to be added.
To address this a more generic 'vendor-specific' method is introduced,
guiding users to refer to vendor specific documentation and system logs
for detailed vendor specific recovery mechanism.

Add a recovery method 'WEDGED=vendor-specific' for such errors.
Vendors must provide additional recovery documentation if this method
is used.

It is the responsibility of the consumer to refer to the correct vendor
specific documentation and usecase before attempting a recovery.

For example: If driver is XE KMD, the consumer must refer
to the documentation of 'Device Wedging' under 'Documentation/gpu/xe/'

Recovery script contributed by Raag

v2: fix documentation (Raag)
v3: add more details to commit message (Sima, Rodrigo, Raag)
    add an example to the documentation (by Raag)

Cc: André Almeida <andrealmeid at igalia.com>
Cc: Christian König <christian.koenig at amd.com>
Cc: David Airlie <airlied at gmail.com>
Co-developed-by: Raag Jadav <raag.jadav at intel.com>
Signed-off-by: Raag Jadav <raag.jadav at intel.com>
Signed-off-by: Riana Tauro <riana.tauro at intel.com>
---
 Documentation/gpu/drm-uapi.rst | 41 +++++++++++++++++++++++++++++-----
 drivers/gpu/drm/drm_drv.c      |  2 ++
 include/drm/drm_device.h       |  4 ++++
 3 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
index 843facf01b2d..a1a5a4de68ea 100644
--- a/Documentation/gpu/drm-uapi.rst
+++ b/Documentation/gpu/drm-uapi.rst
@@ -421,10 +421,13 @@ Recovery
 Current implementation defines three recovery methods, out of which, drivers
 can use any one, multiple or none. Method(s) of choice will be sent in the
 uevent environment as ``WEDGED=<method1>[,..,<methodN>]`` in order of less to
-more side-effects. If driver is unsure about recovery or method is unknown
-(like soft/hard system reboot, firmware flashing, physical device replacement
-or any other procedure which can't be attempted on the fly), ``WEDGED=unknown``
-will be sent instead.
+more side-effects. If recovery method is specific to vendor
+``WEDGED=vendor-specific`` will be sent and userspace should refer to vendor
+specific documentation for further recovery steps. As an example if the driver
+is 'xe' then the documentation of 'Device Wedging' of xe driver needs to be
+referred for the recovery mechanism.
+If driver is unsure about recovery or method is unknown, ``WEDGED=unknown``
+will be sent instead
 
 Userspace consumers can parse this event and attempt recovery as per the
 following expectations.
@@ -435,6 +438,7 @@ following expectations.
     none            optional telemetry collection
     rebind          unbind + bind driver
     bus-reset       unbind + bus reset/re-enumeration + bind
+    vendor-specific vendor specific recovery method
     unknown         consumer policy
     =============== ========================================
 
@@ -472,8 +476,12 @@ erroring out, all device memory should be unmapped and file descriptors should
 be closed to prevent leaks or undefined behaviour. The idea here is to clear the
 device of all user context beforehand and set the stage for a clean recovery.
 
-Example
--------
+For ``WEDGED=vendor-specific`` recovery method, it is the responsibility of the
+consumer to check the driver documentation and the usecase before attempting
+a recovery.
+
+Example - rebind
+----------------
 
 Udev rule::
 
@@ -491,6 +499,27 @@ Recovery script::
     echo -n $DEVICE > $DRIVER/unbind
     echo -n $DEVICE > $DRIVER/bind
 
+Example - vendor-specific
+-------------------------
+
+Udev rule::
+
+    SUBSYSTEM=="drm", ENV{WEDGED}=="vendor-specific", DEVPATH=="*/drm/card[0-9]",
+    RUN+="/path/to/vendor_specific_recovery.sh $env{DEVPATH}"
+
+Recovery script::
+
+    #!/bin/sh
+
+    DEVPATH=$(readlink -f /sys/$1/device)
+    DRIVERPATH=$(readlink -f $DEVPATH/driver)
+    DRIVER=$(basename $DRIVERPATH)
+
+    if [ "$DRIVER" = "xe" ]; then
+        # Refer XE documentation and check usecase and recovery procedure
+    fi
+
+
 Customization
 -------------
 
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index cdd591b11488..0ac723a46a91 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -532,6 +532,8 @@ static const char *drm_get_wedge_recovery(unsigned int opt)
 		return "rebind";
 	case DRM_WEDGE_RECOVERY_BUS_RESET:
 		return "bus-reset";
+	case DRM_WEDGE_RECOVERY_VENDOR:
+		return "vendor-specific";
 	default:
 		return NULL;
 	}
diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
index a33aedd5e9ec..59fd3f4d5995 100644
--- a/include/drm/drm_device.h
+++ b/include/drm/drm_device.h
@@ -26,10 +26,14 @@ struct pci_controller;
  * Recovery methods for wedged device in order of less to more side-effects.
  * To be used with drm_dev_wedged_event() as recovery @method. Callers can
  * use any one, multiple (or'd) or none depending on their needs.
+ *
+ * Refer to "Device Wedging" chapter in Documentation/gpu/drm-uapi.rst for more
+ * details.
  */
 #define DRM_WEDGE_RECOVERY_NONE		BIT(0)	/* optional telemetry collection */
 #define DRM_WEDGE_RECOVERY_REBIND	BIT(1)	/* unbind + bind driver */
 #define DRM_WEDGE_RECOVERY_BUS_RESET	BIT(2)	/* unbind + reset bus device + bind */
+#define DRM_WEDGE_RECOVERY_VENDOR	BIT(3)	/* vendor specific recovery method */
 
 /**
  * struct drm_wedge_task_info - information about the guilty task of a wedge dev
-- 
2.47.1