On Mon, May 30, 2016 at 12:57:09PM +0300, Mika Westerberg wrote: > +Rafael > > On Fri, May 27, 2016 at 01:10:37PM +0200, Peter Wu wrote: > > On Wed, May 25, 2016 at 04:55:35PM +0300, Mika Westerberg wrote: > > > On Wed, May 25, 2016 at 12:53:01AM +0200, Peter Wu wrote: > > > > Since "PCI: Add runtime PM support for PCIe ports", the parent PCIe port > > > > can be runtime-suspended which disables power resources via ACPI. This > > > > is incompatible with DSM, resulting in a GPU device which is still in D3 > > > > and locks up the kernel on resume. > > > > > > > > Mirror the behavior of Windows 8 and newer[1] (as observed via an AMLi > > > > debugger trace) and stop using the DSM functions for D3cold when power > > > > resources are available on the parent PCIe port. > > > > > > > > [1]: https://msdn.microsoft.com/windows/hardware/drivers/bringup/firmware-requirements-for-d3cold > > > > > > > > Signed-off-by: Peter Wu <peter@xxxxxxxxxxxxx> > > > > --- > > > > drivers/gpu/drm/nouveau/nouveau_acpi.c | 34 ++++++++++++++++++++++++++++++---- > > > > 1 file changed, 30 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_acpi.c b/drivers/gpu/drm/nouveau/nouveau_acpi.c > > > > index df9f73e..e469df7 100644 > > > > --- a/drivers/gpu/drm/nouveau/nouveau_acpi.c > > > > +++ b/drivers/gpu/drm/nouveau/nouveau_acpi.c > > > > @@ -46,6 +46,7 @@ static struct nouveau_dsm_priv { > > > > bool dsm_detected; > > > > bool optimus_detected; > > > > bool optimus_flags_detected; > > > > + bool optimus_skip_dsm; > > > > acpi_handle dhandle; > > > > acpi_handle rom_handle; > > > > } nouveau_dsm_priv; > > > > @@ -212,8 +213,26 @@ static const struct vga_switcheroo_handler nouveau_dsm_handler = { > > > > .get_client_id = nouveau_dsm_get_client_id, > > > > }; > > > > > > > > +/* Firmware supporting Windows 8 or later do not use _DSM to put the device into > > > > + * D3cold, they instead rely on disabling power resources on the parent. */ > > > > +static bool nouveau_pr3_present(struct pci_dev *pdev) > > > > +{ > > > > + struct pci_dev *parent_pdev = pci_upstream_bridge(pdev); > > > > + struct acpi_device *ad; > > > > > > Nit: please call this adev instead of ad. > > > > Will do. > > > > > > + > > > > + if (!parent_pdev) > > > > + return false; > > > > + > > > > + ad = ACPI_COMPANION(&parent_pdev->dev); > > > > + if (!ad) > > > > + return false; > > > > + > > > > + return ad->power.flags.power_resources; > > > > > > Is this sufficient to tell if the parent device has _PR3? I thought it > > > returns true if it has power resources in general, not necessarily _PR3. > > > > > > Otherwise this looks okay to me. > > > > It is indeed set whenever there is any _PRx method. I wonder if it is > > appropriate to access fields directly like this, perhaps this would be > > more accurate (based on device_pm.c): > > > > /* Check whether the _PR3 method is available. */ > > return adev->power.states[ACPI_STATE_D3_COLD].flags.valid; > > > > I am also considering adding a check in case the pcieport driver does > > not support D3cold via runtime PM, what do you think of this? > > > > if (!parent_pdev) > > return false; > > /* If the PCIe port does not support D3cold via runtime PM, allow a > > * fallback to the Optimus DSM method to put the device in D3cold. */ > > if (parent_pdev->no_d3cold) > > return false; > > > > This is needed to avoid the regression reported in the cover letter, but > > also allows pre-2015 systems to (still) have the D3cold possibility. > > The _DSM method with 0 as index parameter should return a bit field > telling which functions are supported. Sane BIOS disables that > particular function if it detects Windows 8 and newer. Have you checked > if that's the case? > > Then you can call _DSM only if it is supported and otherwise expect the > parent device's power resources to turn off power when runtime > suspended. The _DSM methods (for the Nvidia device) are often still included and functions are reported as supported. I guess that vendors just check whether it is working and do not bother removing legacy functions. The Acer case below seems exceptional. I suggested the no_d3cold check such that DSM can still be called even though the runtime PM on the PCIe port does nothing. > > Out of curiosity I looked up an pre-2015 laptop (found Acer V5-573G, > > apparently from November 2013, Windows 8.1) and extracted the ACPI > > tables from the BIOS images. BIOS 2.28 (2014/05/13) introduces support > > for power resources on the parent devicea(\_SB.PCI0.PEG0._PR3 and a > > related NVP3 device) when _OSI("Windows 2013") is true. (This is added > > as alternative for the old DSM interface.) > > > > Maybe 2014 is also an appropriate cutoff date? I wonder if it is > > feasible to detect firmware use of _OSI("Windows 2013") and use that > > instead of the BIOS year. > > Using BIOS year works even if there is no ACPI available. I thought that you need support from ACPI to put a device in D3cold? > What comes to the cutoff date, I discussed with Rafael and it was > decided that we use the same year Windows 10 was released to be on the > safe side. Reading the links you provided here: > > https://msdn.microsoft.com/fi-fi/windows/hardware/drivers/bringup/device-power-management > https://msdn.microsoft.com/en-us/library/windows/hardware/hh967709(v=vs.85).aspx > > it seems that from Windows 8 they started transitioning devices into > D3cold during runtime as well. My impression from the ACPI tables I have seen so far is that power resources support is enabled for Windows 2012 (Win8) or newer. -- Kind regards, Peter Wu https://lekensteyn.nl -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
