[PATCH v3] drm/i915: Invoke another _DSM to enable MUX on HP Workstation laptops

[Kai-Heng Feng]

On Wed, May 12, 2021 at 2:19 AM Ville Syrjälä
<ville.syrjala at linux.intel.com> wrote:
>
> On Mon, Apr 26, 2021 at 11:24:10PM +0800, Kai-Heng Feng wrote:
> > On HP Fury G7 Workstations, graphics output is re-routed from Intel GFX
> > to discrete GFX after S3. This is not desirable, because userspace will
> > treat connected display as a new one, losing display settings.
> >
> > The expected behavior is to let discrete GFX drives all external
> > displays.
> >
> > The platform in question uses ACPI method \_SB.PCI0.HGME to enable MUX.
> > The method is inside the another _DSM, so add the _DSM and call it
> > accordingly.
> >
> > I also tested some MUX-less and iGPU only laptops with that _DSM, no
> > regression was found.
> >
> > v3:
> >  - Remove BXT from names.
> >  - Change the parameter type.
> >  - Fold the function into intel_modeset_init_hw().
> >
> > v2:
> >  - Forward declare struct pci_dev.
> >
> > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/3113
> > References: https://lore.kernel.org/intel-gfx/1460040732-31417-4-git-send-email-animesh.manna@intel.com/
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> > ---
> >  drivers/gpu/drm/i915/display/intel_acpi.c    | 18 ++++++++++++++++++
> >  drivers/gpu/drm/i915/display/intel_acpi.h    |  3 +++
> >  drivers/gpu/drm/i915/display/intel_display.c |  2 ++
> >  3 files changed, 23 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
> > index 833d0c1be4f1..d008d3976261 100644
> > --- a/drivers/gpu/drm/i915/display/intel_acpi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_acpi.c
> > @@ -13,12 +13,17 @@
> >  #include "intel_display_types.h"
> >
> >  #define INTEL_DSM_REVISION_ID 1 /* For Calpella anyway... */
> > +#define INTEL_DSM_FN_PLATFORM_MUX_ENABLE 0 /* No args */
>
> This block of defines is for the other DSM. We don't want to
> mix these up. We also want to name it according to the spec,
> so something like GET_BIOS_DATA_FUNCS_SUPPORTED. Similarly
> for the intel_dsm_enable_mux() wrapper function. + it needs
> a comment to document that some BIOSes abuse it to do MUX
> initialization and whatnot.

Will do.


>
> We should perhaps rename all the old DSM stuff to
> something a bit less generic as well...

I can rename them as well. But what's the naming scheme you prefer?

>
> >  #define INTEL_DSM_FN_PLATFORM_MUX_INFO 1 /* No args */
> >
> >  static const guid_t intel_dsm_guid =
> >       GUID_INIT(0x7ed873d3, 0xc2d0, 0x4e4f,
> >                 0xa8, 0x54, 0x0f, 0x13, 0x17, 0xb0, 0x1c, 0x2c);
> >
> > +static const guid_t intel_dsm_guid2 =
> > +     GUID_INIT(0x3e5b41c6, 0xeb1d, 0x4260,
> > +               0x9d, 0x15, 0xc7, 0x1f, 0xba, 0xda, 0xe4, 0x14);
> > +
> >  static char *intel_dsm_port_name(u8 id)
> >  {
> >       switch (id) {
> > @@ -176,6 +181,19 @@ void intel_unregister_dsm_handler(void)
> >  {
> >  }
> >
> > +void intel_dsm_enable_mux(struct drm_i915_private *i915)
> > +{
> > +     struct pci_dev *pdev = i915->drm.pdev;
> > +     acpi_handle dhandle;
> > +
> > +     dhandle = ACPI_HANDLE(&pdev->dev);
> > +     if (!dhandle)
> > +             return;
> > +
> > +     acpi_evaluate_dsm(dhandle, &intel_dsm_guid2, INTEL_DSM_REVISION_ID,
> > +                       INTEL_DSM_FN_PLATFORM_MUX_ENABLE, NULL);
> > +}
> > +
> >  /*
> >   * ACPI Specification, Revision 5.0, Appendix B.3.2 _DOD (Enumerate All Devices
> >   * Attached to the Display Adapter).
> > diff --git a/drivers/gpu/drm/i915/display/intel_acpi.h b/drivers/gpu/drm/i915/display/intel_acpi.h
> > index e8b068661d22..def013cf6308 100644
> > --- a/drivers/gpu/drm/i915/display/intel_acpi.h
> > +++ b/drivers/gpu/drm/i915/display/intel_acpi.h
> > @@ -11,11 +11,14 @@ struct drm_i915_private;
> >  #ifdef CONFIG_ACPI
> >  void intel_register_dsm_handler(void);
> >  void intel_unregister_dsm_handler(void);
> > +void intel_dsm_enable_mux(struct drm_i915_private *i915);
> >  void intel_acpi_device_id_update(struct drm_i915_private *i915);
> >  #else
> >  static inline void intel_register_dsm_handler(void) { return; }
> >  static inline void intel_unregister_dsm_handler(void) { return; }
> >  static inline
> > +void intel_dsm_enable_mux(struct drm_i915_private *i915) { return; }
> > +static inline
> >  void intel_acpi_device_id_update(struct drm_i915_private *i915) { return; }
> >  #endif /* CONFIG_ACPI */
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> > index a10e26380ef3..d79dae370b20 100644
> > --- a/drivers/gpu/drm/i915/display/intel_display.c
> > +++ b/drivers/gpu/drm/i915/display/intel_display.c
> > @@ -11472,6 +11472,8 @@ void intel_modeset_init_hw(struct drm_i915_private *i915)
> >  {
> >       struct intel_cdclk_state *cdclk_state;
> >
> > +     intel_dsm_enable_mux(i915);
> > +
>
> This should probably be somewhere around where we do all the other
> semi ACPI related init (OpRegion/etc.).

Hmm, but Jani prefers to put it inside intel_modeset_*() helpers. But
I don't see any opregion related functions are being called by
intel_modeset_*() helpers. Any suggestion?

Kai-Heng

>
> >       if (!HAS_DISPLAY(i915))
> >               return;
> >
> > --
> > 2.30.2
>
> --
> Ville Syrjälä
> Intel