video: fbdev: savagefb: use arch_phys_wc_add() and ioremap_wc()

Author: Luis R. Rodriguez <>

This driver uses the same area for MTRR as for the ioremap().
Convert the driver from using the x86 specific MTRR code to
the architecture agnostic arch_phys_wc_add(). arch_phys_wc_add()
will avoid MTRR if write-combining is available, in order to
take advantage of that also ensure the ioremap'd area is requested
as write-combining.

There are a few motivations for this:

a) Take advantage of PAT when available

b) Help bury MTRR code away, MTRR is architecture specific and on
   x86 its replaced by PAT

c) Help with the goal of eventually using _PAGE_CACHE_UC over
   _PAGE_CACHE_UC_MINUS on x86 on ioremap_nocache() (see commit
   de33c442e titled "x86 PAT: fix performance drop for glx,
   use UC minus for ioremap(), ioremap_nocache() and

The conversion done is expressed by the following Coccinelle
SmPL patch, it additionally required manual intervention to
address all the #ifdery and removal of redundant things which
arch_phys_wc_add() already addresses such as verbose message
about when MTRR fails and doing nothing when we didn't get
an MTRR.

@ mtrr_found @
expression index, base, size;

-index = mtrr_add(base, size, MTRR_TYPE_WRCOMB, 1);
+index = arch_phys_wc_add(base, size);

@ mtrr_rm depends on mtrr_found @
expression mtrr_found.index, mtrr_found.base, mtrr_found.size;

-mtrr_del(index, base, size);

@ mtrr_rm_zero_arg depends on mtrr_found @
expression mtrr_found.index;

-mtrr_del(index, 0, 0);

@ mtrr_rm_fb_info depends on mtrr_found @
struct fb_info *info;
expression mtrr_found.index;

-mtrr_del(index, info->fix.smem_start, info->fix.smem_len);

@ ioremap_replace_nocache depends on mtrr_found @
struct fb_info *info;
expression base, size;

-info->screen_base = ioremap_nocache(base, size);
+info->screen_base = ioremap_wc(base, size);

@ ioremap_replace_default depends on mtrr_found @
struct fb_info *info;
expression base, size;

-info->screen_base = ioremap(base, size);
+info->screen_base = ioremap_wc(base, size);

Generated-by: Coccinelle SmPL
Cc: Antonino Daplas 
Cc: Jean-Christophe Plagniol-Villard 
Cc: Tomi Valkeinen 
Cc: Suresh Siddha 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Juergen Gross 
Cc: Daniel Vetter 
Cc: Andy Lutomirski 
Cc: Dave Airlie 
Signed-off-by: Luis R. Rodriguez 
Reviewed-by: Dave Airlie 
Signed-off-by: Tomi Valkeinen 
 drivers/video/fbdev/savage/savagefb.h        |  4 +---
 drivers/video/fbdev/savage/savagefb_driver.c | 17 +++--------------
 2 files changed, 4 insertions(+), 17 deletions(-)
diff --git a/drivers/video/fbdev/savage/savagefb.h b/drivers/video/fbdev/savage/savagefb.h
index 8ff4ab1..aba04af 100644
--- a/drivers/video/fbdev/savage/savagefb.h
+++ b/drivers/video/fbdev/savage/savagefb.h
@@ -213,9 +213,7 @@ struct savagefb_par {
 		void   __iomem *vbase;
 		u32    pbase;
 		u32    len;
-		int    mtrr;
+		int    wc_cookie;
 	} video;
 	struct {
diff --git a/drivers/video/fbdev/savage/savagefb_driver.c b/drivers/video/fbdev/savage/savagefb_driver.c
index 4dbf45f..6c77ab0 100644
--- a/drivers/video/fbdev/savage/savagefb_driver.c
+++ b/drivers/video/fbdev/savage/savagefb_driver.c
@@ -57,10 +57,6 @@
 #include <asm/irq.h>
 #include <asm/pgtable.h>
-#include <asm/mtrr.h>
 #include "savagefb.h"
@@ -1775,7 +1771,7 @@ static int savage_map_video(struct fb_info *info, int video_len)
 	par->video.pbase = pci_resource_start(par->pcidev, resource);
 	par->video.len   = video_len;
-	par->video.vbase = ioremap(par->video.pbase, par->video.len);
+	par->video.vbase = ioremap_wc(par->video.pbase, par->video.len);
 	if (!par->video.vbase) {
 		printk("savagefb: unable to map screen memory\n");
@@ -1787,11 +1783,7 @@ static int savage_map_video(struct fb_info *info, int video_len)
 	info->fix.smem_start = par->video.pbase;
 	info->fix.smem_len   = par->video.len - par->cob_size;
 	info->screen_base    = par->video.vbase;
-	par->video.mtrr = mtrr_add(par->video.pbase, video_len,
-				   MTRR_TYPE_WRCOMB, 1);
+	par->video.wc_cookie = arch_phys_wc_add(par->video.pbase, video_len);
 	/* Clear framebuffer, it's all white in memory after boot */
 	memset_io(par->video.vbase, 0, par->video.len);
@@ -1806,10 +1798,7 @@ static void savage_unmap_video(struct fb_info *info)
 	if (par->video.vbase) {
-		mtrr_del(par->video.mtrr, par->video.pbase, par->video.len);
+		arch_phys_wc_del(par->video.wc_cookie);
 		par->video.vbase = NULL;
 		info->screen_base = NULL;