Re: [PATCH] drm/xe/fbdev: Limit the usage of stolen for LNL+

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Jul 11, 2024 at 11:31:54AM -0500, Lucas De Marchi wrote:
> On Thu, Jul 11, 2024 at 10:43:39AM GMT, Uma Shankar wrote:
> >As per recommendation in the workarounds:
> >WA_14021987551, Wa_16023588340:
> >
> >There is an issue with accessing Stolen memory pages due a
> >hardware limitation. Limit the usage of stolen memory for
> >fbdev for LNL+. Don't use BIOS FB from stolen on LNL+ and
> >assign the same from system memory.
> >
> >Signed-off-by: Uma Shankar <uma.shankar@intel.com>
> >---
> > drivers/gpu/drm/xe/display/intel_fbdev_fb.c   | 10 +++++++++-
> > drivers/gpu/drm/xe/display/xe_plane_initial.c | 10 ++++++++++
> > 2 files changed, 19 insertions(+), 1 deletion(-)
> >
> >diff --git a/drivers/gpu/drm/xe/display/intel_fbdev_fb.c b/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> >index 816ad13821a8..8fda8745ce0a 100644
> >--- a/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> >+++ b/drivers/gpu/drm/xe/display/intel_fbdev_fb.c
> >@@ -37,7 +37,14 @@ struct intel_framebuffer *intel_fbdev_fb_alloc(struct drm_fb_helper *helper,
> > 	size = PAGE_ALIGN(size);
> > 	obj = ERR_PTR(-ENODEV);
> >
> >-	if (!IS_DGFX(xe)) {
> >+	/*
> >+	 * WA_14021987551, Wa_16023588340:
> 
> not the proper way to handle WAs in xe. Please use XE_WA()
> 
> 
> >+	 * There is an issue with accessing Stolen memory pages
> >+	 * due a hardware limitation. Limit the usage of stolen
> >+	 * memory for fbdev for LNL+. Don't use BIOS FB from
> >+	 * stolen on LNL+ and assign the same from system memory
> 
> I wonder if we can't simply set to 0 the available stolen space after the
> places that really need it already had their allocation done.

FBC needs stolen.

-- 
Ville Syrjälä
Intel