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

Author: Luis R. Rodriguez <>

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: Jean-Christophe Plagniol-Villard 
Cc: Tomi Valkeinen 
Cc: Laurent Pinchart 
Cc: Jingoo Han 
Cc: Suresh Siddha 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Juergen Gross 
Cc: Daniel Vetter 
Cc: Andy Lutomirski 
Cc: Dave Airlie 
Cc: Antonino Daplas 
Signed-off-by: Luis R. Rodriguez 
Reviewed-by: Dave Airlie 
Signed-off-by: Tomi Valkeinen 
 drivers/video/fbdev/neofb.c | 26 +++++++-------------------
 include/video/neomagic.h    |  5 +----
 2 files changed, 8 insertions(+), 23 deletions(-)
diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c
index 44f99a6..db023a9 100644
--- a/drivers/video/fbdev/neofb.c
+++ b/drivers/video/fbdev/neofb.c
@@ -71,11 +71,6 @@
 #include <asm/io.h>
 #include <asm/irq.h>
 #include <asm/pgtable.h>
-#include <asm/mtrr.h>
 #include <video/vga.h>
 #include <video/neomagic.h>
@@ -1710,6 +1705,7 @@ static int neo_map_video(struct fb_info *info, struct pci_dev *dev,
 			 int video_len)
 	//unsigned long addr;
+	struct neofb_par *par = info->par;
@@ -1723,7 +1719,7 @@ static int neo_map_video(struct fb_info *info, struct pci_dev *dev,
 	info->screen_base =
-	    ioremap(info->fix.smem_start, info->fix.smem_len);
+	    ioremap_wc(info->fix.smem_start, info->fix.smem_len);
 	if (!info->screen_base) {
 		printk("neofb: unable to map screen memory\n");
@@ -1733,11 +1729,8 @@ static int neo_map_video(struct fb_info *info, struct pci_dev *dev,
 		printk(KERN_INFO "neofb: mapped framebuffer at %p\n",
-	((struct neofb_par *)(info->par))->mtrr =
-		mtrr_add(info->fix.smem_start, pci_resource_len(dev, 0),
+	par->wc_cookie = arch_phys_wc_add(info->fix.smem_start,
+					  pci_resource_len(dev, 0));
 	/* Clear framebuffer, it's all white in memory after boot */
 	memset_io(info->screen_base, 0, info->fix.smem_len);
@@ -1754,16 +1747,11 @@ static int neo_map_video(struct fb_info *info, struct pci_dev *dev,
 static void neo_unmap_video(struct fb_info *info)
-	DBG("neo_unmap_video");
+	struct neofb_par *par = info->par;
-	{
-		struct neofb_par *par = info->par;
+	DBG("neo_unmap_video");
-		mtrr_del(par->mtrr, info->fix.smem_start,
-			 info->fix.smem_len);
-	}
+	arch_phys_wc_del(par->wc_cookie);
 	info->screen_base = NULL;
diff --git a/include/video/neomagic.h b/include/video/neomagic.h
index bc5013e..91e225a 100644
--- a/include/video/neomagic.h
+++ b/include/video/neomagic.h
@@ -159,10 +159,7 @@ struct neofb_par {
 	unsigned char VCLK3NumeratorHigh;
 	unsigned char VCLK3Denominator;
 	unsigned char VerticalExt;
-	int mtrr;
+	int wc_cookie;
 	u8 __iomem *mmio_vbase;
 	u8 cursorOff;
 	u8 *cursorPad;		/* Must die !! */