drm/radeon: Use direct mapping for fast fb access on RS690

This patch allows the CPU to map the stolen vram segment
directly rather than going through the PCI BAR.  This
significantly improves performance for certain workloads with
a properly patched ddx.

Use radeon.fastfb=1 to enable it (disabled by default).
Currently only supported on RS690, but support for RS780/880
and newer APUs may be added eventually.

Signed-off-by: Samuel Li <samuel.li@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 8bd875304441..730d3359af60 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -95,6 +95,7 @@ extern int radeon_hw_i2c;
 extern int radeon_pcie_gen2;
 extern int radeon_msi;
 extern int radeon_lockup_timeout;
+extern int radeon_fastfb;
 
 /*
  * Copy from radeon_drv.h so we don't have to include both and have conflicting
@@ -1616,6 +1617,7 @@ struct radeon_device {
         bool                            suspend;
         bool                            need_dma32;
         bool                            accel_working;
+        bool                            fastfb_working; /* IGP feature*/
         struct radeon_surface_reg surface_regs[RADEON_GEM_MAX_SURFACES];
         const struct firmware *me_fw;   /* all family ME firmware */
         const struct firmware *pfp_fw;  /* r6/700 PFP firmware */