• Paulo Zanoni's avatar
    drm/i915: fully apply WaSkipStolenMemoryFirstPage · 3c6b29b2
    Paulo Zanoni authored
    Don't even tell the mm allocator to handle the first page of stolen on
    the affected platforms. This means that we won't inherit the FB in
    case the BIOS decides to put it at the start of stolen. But the BIOS
    should not be putting it at the start of stolen since it's going to
    get corrupted. I suppose the bug here is that some pixels at the very
    top of the screen will be corrupted, so it's not exactly easy to
    notice.
    
    We have confirmation that the first page of stolen does actually get
    corrupted, so I really think we should do this in order to avoid any
    possible future headaches, even if that means losing BIOS framebuffer
    inheritance. Let's not use the HW in a way it's not supposed to be
    used.
    
    Notice that now ggtt->stolen_usable_size won't reflect the ending
    address of the stolen usable range anymore, so we have to fix the
    places that rely on this. To simplify, we'll just use U64_MAX.
    
    v2: don't even put the first page on the mm (Chris)
    v3: drm_mm_init() takes size instead of end as argument (Ville)
    v4: add a comment explaining the reserved ranges (Chris)
        use 0 for start and U64_MAX for end when possible (Chris)
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94605
    Cc: Chris Wilson <chris@chris-wilson.co.uk>
    Signed-off-by: default avatarPaulo Zanoni <paulo.r.zanoni@intel.com>
    Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
    Link: http://patchwork.freedesktop.org/patch/msgid/1481808235-27607-1-git-send-email-paulo.r.zanoni@intel.com
    3c6b29b2
i915_gem_stolen.c 19.2 KB