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 <[email protected]>
---
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.

+        */
+       if (!IS_DGFX(xe) && (DISPLAY_VER(xe) < 20)) {

extra parenthesis not needed and I think the rule to be added in
xe_wa_oob.rules would be about GRAPHICS_VERSION(2004) or
PLATFORM(LUNARLAKE) to avoid this propagating to future platforms.

                obj = xe_bo_create_pin_map(xe, xe_device_get_root_tile(xe),
                                           NULL, size,
                                           ttm_bo_type_kernel, 
XE_BO_FLAG_SCANOUT |
@@ -48,6 +55,7 @@ struct intel_framebuffer *intel_fbdev_fb_alloc(struct 
drm_fb_helper *helper,
                else
                        drm_info(&xe->drm, "Allocated fbdev into stolen failed: 
%li\n", PTR_ERR(obj));
        }
+
        if (IS_ERR(obj)) {
                obj = xe_bo_create_pin_map(xe, xe_device_get_root_tile(xe), 
NULL, size,
                                           ttm_bo_type_kernel, 
XE_BO_FLAG_SCANOUT |
diff --git a/drivers/gpu/drm/xe/display/xe_plane_initial.c 
b/drivers/gpu/drm/xe/display/xe_plane_initial.c
index 5eccd6abb3ef..80dd6b64c921 100644
--- a/drivers/gpu/drm/xe/display/xe_plane_initial.c
+++ b/drivers/gpu/drm/xe/display/xe_plane_initial.c
@@ -104,6 +104,16 @@ initial_plane_bo(struct xe_device *xe,
                phys_base = base;
                flags |= XE_BO_FLAG_STOLEN;

+               /*
+                * 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
+                */
+               if (DISPLAY_VER(xe) >= 20)
+                       return NULL;

same as above

Lucas De Marchi

+
                /*
                 * If the FB is too big, just don't use it since fbdev is not 
very
                 * important and we should probably use that space with FBC or 
other
--
2.42.0

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