On 30 May 2016 at 12:23, Peter Wu <peter@xxxxxxxxxxxxx> wrote: > On Mon, May 30, 2016 at 11:48:34AM +0100, Emil Velikov wrote: >> On 27 May 2016 at 22:31, Peter Wu <peter@xxxxxxxxxxxxx> wrote: >> > On Fri, May 27, 2016 at 02:01:39PM +0100, Emil Velikov wrote: >> >> Hi Peter, >> >> >> >> On 24 May 2016 at 23:53, Peter Wu <peter@xxxxxxxxxxxxx> 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; >> >> > + >> >> > + if (!parent_pdev) >> >> > + return false; >> >> > + >> >> > + ad = ACPI_COMPANION(&parent_pdev->dev); >> >> > + if (!ad) >> >> > + return false; >> >> > + >> >> > + return ad->power.flags.power_resources; >> >> > +} >> >> > + >> >> > static void nouveau_dsm_pci_probe(struct pci_dev *pdev, bool *has_mux, >> >> > - bool *has_opt, bool *has_opt_flags) >> >> > + bool *has_opt, bool *has_opt_flags, >> >> > + bool *has_power_resources) >> >> > { >> >> > acpi_handle dhandle; >> >> > bool supports_mux; >> >> > @@ -238,6 +257,7 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev, bool *has_mux, >> >> > *has_mux = supports_mux; >> >> > *has_opt = !!optimus_funcs; >> >> > *has_opt_flags = optimus_funcs & (1 << NOUVEAU_DSM_OPTIMUS_FLAGS); >> >> > + *has_power_resources = false; >> >> > >> >> > if (optimus_funcs) { >> >> > uint32_t result; >> >> > @@ -247,6 +267,8 @@ static void nouveau_dsm_pci_probe(struct pci_dev *pdev, bool *has_mux, >> >> > (result & OPTIMUS_ENABLED) ? "enabled" : "disabled", >> >> > (result & OPTIMUS_DYNAMIC_PWR_CAP) ? "dynamic power, " : "", >> >> > (result & OPTIMUS_HDA_CODEC_MASK) ? "hda bios codec supported" : ""); >> >> > + >> >> > + *has_power_resources = nouveau_pr3_present(pdev); >> >> > } >> >> > } >> >> > >> >> > @@ -258,6 +280,7 @@ static bool nouveau_dsm_detect(void) >> >> > bool has_mux = false; >> >> > bool has_optimus = false; >> >> > bool has_optimus_flags = false; >> >> > + bool has_power_resources = false; >> >> > int vga_count = 0; >> >> > bool guid_valid; >> >> > bool ret = false; >> >> > @@ -273,14 +296,14 @@ static bool nouveau_dsm_detect(void) >> >> > vga_count++; >> >> > >> >> > nouveau_dsm_pci_probe(pdev, &has_mux, &has_optimus, >> >> > - &has_optimus_flags); >> >> > + &has_optimus_flags, &has_power_resources); >> >> > } >> >> > >> >> > while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_3D << 8, pdev)) != NULL) { >> >> > vga_count++; >> >> > >> >> > nouveau_dsm_pci_probe(pdev, &has_mux, &has_optimus, >> >> > - &has_optimus_flags); >> >> > + &has_optimus_flags, &has_power_resources); >> >> > } >> >> > >> >> This and earlier patch break things in a subtle way. >> >> >> >> Namely: upon the second (and any later) call into the >> >> nouveau_dsm_pci_probe() function, the had_foo flags are reset. Thus >> >> only the specifics of the _final_ device are being used (at a later >> >> stage). IMHO one should change that to "_any_ device", which will >> >> match the original code and the actual intent further down in the >> >> file. >> > >> > The flags are only reset if any of the MUX or Optimus handles are found. >> > If both are missing, the flags are not overridden. This is from patch 1: >> > >> > + /* Does not look like a Nvidia device. */ >> > + if (!supports_mux && !supports_opt) >> > + return; >> > >> This is precisely what I'm saying, and I think it's wrong/strange. If >> you've detected that device A support_{X,Y}, you'll reset the >> support_{X,Y} flag anyway if device B is present... (continues further >> down) > > The flags will only be reset when device B supports at least one > function. > Indeed. Seems like I completely misread the code on multiple occasions. Sorry about the noise. >> > The reason why later calls override early ones is because some Optimus >> > laptops have the _DSM method on both the Intel GPU (00:02.0) and the >> > Nvidia one (01:00.0). >> > >> I agree with Lukas idea that one could/should be checking for nvidia >> devices (perhaps in nouveau_dsm_pci_probe() or just before calling it >> ?). > > That could break PM on at least two Acer laptops. The Acer Travelmate > 8472TG from 2011 (acpidump[1]) has two DSM on the Nvidia and Intel ACPI > handles: > > - Nvidia: supports MXM methods only. > - Intel: supports the older Nvidia UUID (for toggling power and > possibly other things). > > [1]: https://github.com/Bumblebee-Project/bbswitch/issues/4#issuecomment-219988501 > > There is also an Acer Aspire 5742G which possibly breaks (linked in the > above issue), but that could be a configuration issue that disabled > Optimus in BIOS (unconfirmed). > > If it matters, both of these laptops have a MXMX method (Select Display > Data Channel), but their MXMI (Return Specification Support Level) and > MXMS (Return MXM Structure) functions are disfunctional. There is also a > MXDS function on both ACPI handles, but these are not hooked to the WMI > interface for some reason. No idea of Acer has hacked up some drivers to > work with this, outside these models I do not know others that are also > affected by this issue. > /me takes a sigh "Why Acer why ..." :-) >> > The previous detection method would fail in this scenario: >> > 1. One device reports support for X and Y (has_x = 1, has_y = 1). Write >> > ACPI handle A to nouveau_dsm_priv.dhandle. >> > 2. Another device reports support for X only (has_x = 1). Write >> > ACPI handle B to nouveau_dsm_priv.dhandle. >> > 3. End result: has_x = 1, has_y = 1, dhandle = B. But ACPI handle B >> > does not really support Y! >> >> ... so to avoid the above case and preserve the original ideas ('do >> not discard earlier device caps' and 'Optimus takes precedence over >> DSM v1') one could do the following: >> >> - decouple the "feature check" and "set the dhandle" >> >> - pick the 'ideal' one based on the feature set provided. if multiple >> pick one based on $insert_heuristics >> - set the dhandle >> >> What do you think ? > > The dhandle is only set when at least one valid DSM was found on the > device. The dhandle assignment could indeed be moved to the caller, > making it more obvious that the dhandle is only valid when the > capabilities are detected (this does not have a functional change > though). I'll do it in the next version. That will be amazing, thanks. Emil -- 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
