For development and testing purposes, the i915.force_probe module
parameter and DRM_I915_FORCE_PROBE kconfig option allow probing of
devices that aren't supported by the driver.
The i915.force_probe module parameter is "unsafe" and setting it taints
the kernel. However, using the kconfig option does not.
Always taint the kernel when force probing a device that is not
supported.
v2: Drop "depends on EXPERT" to avoid build breakage (kernel test robot)
Fixes: 7ef5ef5cdead ("drm/i915: add force_probe module parameter to replace alpha_support")
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxx>
Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
---
drivers/gpu/drm/i915/Kconfig | 12 +++++++-----
drivers/gpu/drm/i915/i915_pci.c | 6 ++++++
2 files changed, 13 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 06a0ca157e89..e4f4d2e3fdfe 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -62,10 +62,11 @@ config DRM_I915_FORCE_PROBE
This is the default value for the i915.force_probe module
parameter. Using the module parameter overrides this option.
- Force probe the i915 for Intel graphics devices that are
- recognized but not properly supported by this kernel version. It is
- recommended to upgrade to a kernel version with proper support as soon
- as it is available.
+ Force probe the i915 driver for Intel graphics devices that are
+ recognized but not properly supported by this kernel version. Force
+ probing an unsupported device taints the kernel. It is recommended to
+ upgrade to a kernel version with proper support as soon as it is
+ available.
It can also be used to block the probe of recognized and fully
supported devices.
@@ -75,7 +76,8 @@ config DRM_I915_FORCE_PROBE
Use "<pci-id>[,<pci-id>,...]" to force probe the i915 for listed
devices. For example, "4500" or "4500,4571".
- Use "*" to force probe the driver for all known devices.
+ Use "*" to force probe the driver for all known devices. Not
+ recommended.
Use "!" right before the ID to block the probe of the device. For
example, "4500,!4571" forces the probe of 4500 and blocks the probe of
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c
index 5fcc9cfed671..c509ea4aa70f 100644
--- a/drivers/gpu/drm/i915/i915_pci.c
+++ b/drivers/gpu/drm/i915/i915_pci.c
@@ -1346,6 +1346,12 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
return -ENODEV;
}
+ if (intel_info->require_force_probe) {
+ dev_info(&pdev->dev, "Force probing unsupported Device ID %04x, tainting kernel\n",
+ pdev->device);
+ add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+ }
+
/* Only bind to function 0 of the device. Early generations
* used function 1 as a placeholder for multi-head. This causes
* us confusion instead, especially on the systems where both
--
2.39.2
