Cc: Rafael
On Wed, 21 Sep 2022, Rodrigo Vivi rodrigo.vivi@intel.com wrote:
The force_probe protection actively avoids the probe of i915 to manage a device that is currently under development. It is a nice protection for future users when getting a new platform but using some older kernel.
However, when we avoid the probe we don't take back the registration of the device. We cannot give up the registration anyway since we can have multiple devices present. For instance an integrated and a discrete one.
When this scenario occurs, the user will not be able to change any of the runtime pm configuration of the unmanaged device. So, it will be blocked in D0 state wasting power. This is specially bad in the case where we have a discrete platform attached, but the user is able to fully use the integrated one for everything else.
So, let's put the protected and unmanaged device in D3. So we can save some power.
Reported-by: Daniel J Blueman daniel@quora.org Cc: stable@vger.kernel.org Cc: Daniel J Blueman daniel@quora.org Cc: Tvrtko Ursulin tvrtko.ursulin@intel.com Cc: Anshuman Gupta anshuman.gupta@intel.com Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com
drivers/gpu/drm/i915/i915_pci.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_pci.c b/drivers/gpu/drm/i915/i915_pci.c index 77e7df21f539..fc3e7c69af2a 100644 --- a/drivers/gpu/drm/i915/i915_pci.c +++ b/drivers/gpu/drm/i915/i915_pci.c @@ -25,6 +25,7 @@ #include <drm/drm_color_mgmt.h> #include <drm/drm_drv.h> #include <drm/i915_pciids.h> +#include <linux/pm_runtime.h> #include "gt/intel_gt_regs.h" #include "gt/intel_sa_media.h" @@ -1304,6 +1305,7 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent) { struct intel_device_info *intel_info = (struct intel_device_info *) ent->driver_data;
- struct device *kdev = &pdev->dev; int err;
if (intel_info->require_force_probe && @@ -1314,6 +1316,12 @@ static int i915_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent) "module parameter or CONFIG_DRM_I915_FORCE_PROBE=%04x configuration option,\n" "or (recommended) check for kernel updates.\n", pdev->device, pdev->device, pdev->device);
/* Let's not waste power if we are not managing the device */pm_runtime_use_autosuspend(kdev);pm_runtime_allow(kdev);pm_runtime_put_autosuspend(kdev);- return -ENODEV; }