Cc: Rafael
On Wed, 21 Sep 2022, Rodrigo Vivi <[email protected]> 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 <[email protected]> > Cc: [email protected] > Cc: Daniel J Blueman <[email protected]> > Cc: Tvrtko Ursulin <[email protected]> > Cc: Anshuman Gupta <[email protected]> > Signed-off-by: Rodrigo Vivi <[email protected]> > --- > 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; > } -- Jani Nikula, Intel Open Source Graphics Center
