[Intel-xe] [PATCH 2/3] drm/xe: Add wrapper function for VGA decode setup

[Shankar, Uma]

> -----Original Message-----
> From: Nikula, Jani <jani.nikula at intel.com>
> Sent: Wednesday, September 20, 2023 3:38 PM
> To: Shankar, Uma <uma.shankar at intel.com>; intel-xe at lists.freedesktop.org
> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>
> Subject: RE: [PATCH 2/3] drm/xe: Add wrapper function for VGA decode setup
> 
> On Wed, 20 Sep 2023, "Shankar, Uma" <uma.shankar at intel.com> wrote:
> >> -----Original Message-----
> >> From: Nikula, Jani <jani.nikula at intel.com>
> >> Sent: Tuesday, September 19, 2023 4:00 PM
> >> To: Shankar, Uma <uma.shankar at intel.com>;
> >> intel-xe at lists.freedesktop.org
> >> Cc: Borah, Chaitanya Kumar <chaitanya.kumar.borah at intel.com>;
> >> Shankar, Uma <uma.shankar at intel.com>
> >> Subject: Re: [PATCH 2/3] drm/xe: Add wrapper function for VGA decode
> >> setup
> >>
> >> On Mon, 18 Sep 2023, Uma Shankar <uma.shankar at intel.com> wrote:
> >> > Some of the VGA functionality is not needed by the Intel Xe driver.
> >> > Adding a wrapper function for VGA decode setup.
> >> >
> >> > Signed-off-by: Uma Shankar <uma.shankar at intel.com>
> >> > ---
> >> >  drivers/gpu/drm/xe/display/ext/i915_utils.c | 5 +++++
> >> >  drivers/gpu/drm/xe/xe_display.h             | 1 +
> >> >  2 files changed, 6 insertions(+)
> >> >
> >> > diff --git a/drivers/gpu/drm/xe/display/ext/i915_utils.c
> >> > b/drivers/gpu/drm/xe/display/ext/i915_utils.c
> >> > index 981edc2788bc..aa3e9ad718c3 100644
> >> > --- a/drivers/gpu/drm/xe/display/ext/i915_utils.c
> >> > +++ b/drivers/gpu/drm/xe/display/ext/i915_utils.c
> >> > @@ -20,3 +20,8 @@ int __i915_inject_probe_error(struct
> >> > drm_i915_private *i915, int err,  {
> >> >     return 0;
> >> >  }
> >> > +
> >> > +unsigned int intel_gmch_vga_set_decode(struct pci_dev *pdev, bool
> >> > +enable_decode) {
> >> > +   return -EIO;
> >> > +}
> >>
> >> We don't really want to add anything new to i915_utils.c. It's just
> >> temporary cruft that had to be taken from i915 to make the rest compile.
> >
> > Hi Jani,
> > Thanks for the feedback.
> >
> > I was looking at any good place to stack it together. There are some
> > misc stuff like this which we may need for some other stuff as well.
> > Should I add a xe_disp_misc file for this or any other suggestion on file which
> we can use.
> 
> Let's take a step back, though.
> 
> Why is this call needed on i915 but not on xe?

Ideally it should be needed even here. Not sure on the exact usage though, the GMCHGraphicsControl
is there on current platforms as well. Trying to gather some info to get clarity.

@ville.syrjala at linux.intel.com Do you know how critical this is or can we defer its enabling and
add support later directly in upstream.

Thanks & Regards,
Uma Shankar

> BR,
> Jani.
> 
> 
> >
> > Regards,
> > Uma Shankar
> >
> >> > diff --git a/drivers/gpu/drm/xe/xe_display.h
> >> > b/drivers/gpu/drm/xe/xe_display.h index 03b7ea9268d4..d7a200e6ec30
> >> > 100644
> >> > --- a/drivers/gpu/drm/xe/xe_display.h
> >> > +++ b/drivers/gpu/drm/xe/xe_display.h
> >> > @@ -38,6 +38,7 @@ void xe_display_pm_suspend(struct xe_device *xe);
> >> > void xe_display_pm_suspend_late(struct xe_device *xe);  void
> >> > xe_display_pm_resume_early(struct xe_device *xe);  void
> >> > xe_display_pm_resume(struct xe_device *xe);
> >> > +unsigned int intel_gmch_vga_set_decode(struct pci_dev *pdev, bool
> >> > +enable_decode);
> >>
> >> We also don't want to add random declarations in xe_display.h either...
> >
> > Yeah, looking deeper seems we don't need it as compat-header is already
> including the same.
> > Will drop this declaration.
> >
> > Regards,
> > Uma Shankar
> >
> >> BR,
> >> Jani.
> >>
> >> >
> >> >  #else
> >>
> >> --
> >> Jani Nikula, Intel
> 
> --
> Jani Nikula, Intel