video: fbdev: pm2fb: 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: Rob Clark 
Cc: Jingoo Han 
Cc: Daniel Vetter 
Cc: Suresh Siddha 
Cc: Ingo Molnar 
Cc: Thomas Gleixner 
Cc: Juergen Gross 
Cc: Andy Lutomirski 
Cc: Dave Airlie 
Cc: Antonino Daplas 
Cc: Jean-Christophe Plagniol-Villard 
Cc: Tomi Valkeinen 
Signed-off-by: Luis R. Rodriguez 
Reviewed-by: Dave Airlie 
Signed-off-by: Tomi Valkeinen 
 drivers/video/fbdev/pm2fb.c | 31 +++++--------------------------
 1 file changed, 5 insertions(+), 26 deletions(-)
diff --git a/drivers/video/fbdev/pm2fb.c b/drivers/video/fbdev/pm2fb.c
index 3b85b64..aa8d288 100644
--- a/drivers/video/fbdev/pm2fb.c
+++ b/drivers/video/fbdev/pm2fb.c
@@ -38,10 +38,6 @@
 #include <linux/fb.h>
 #include <linux/init.h>
 #include <linux/pci.h>
-#include <asm/mtrr.h>
 #include <video/permedia2.h>
 #include <video/cvisionppc.h>
@@ -81,10 +77,7 @@ static char *mode_option;
 static bool lowhsync;
 static bool lowvsync;
 static bool noaccel;
-/* mtrr option */
 static bool nomtrr;
  * The hardware state of the graphics card that isn't part of the
@@ -100,7 +93,7 @@ struct pm2fb_par
 	u32		mem_control;	/* MemControl reg at probe */
 	u32		boot_address;	/* BootAddress reg at probe */
 	u32		palette[16];
-	int		mtrr_handle;
+	int		wc_cookie;
@@ -1637,21 +1630,16 @@ static int pm2fb_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		goto err_exit_mmio;
 	info->screen_base =
-		ioremap_nocache(pm2fb_fix.smem_start, pm2fb_fix.smem_len);
+		ioremap_wc(pm2fb_fix.smem_start, pm2fb_fix.smem_len);
 	if (!info->screen_base) {
 		printk(KERN_WARNING "pm2fb: Can't ioremap smem area.\n");
 		release_mem_region(pm2fb_fix.smem_start, pm2fb_fix.smem_len);
 		goto err_exit_mmio;
-	default_par->mtrr_handle = -1;
 	if (!nomtrr)
-		default_par->mtrr_handle =
-			mtrr_add(pm2fb_fix.smem_start,
-				 pm2fb_fix.smem_len,
+		default_par->wc_cookie = arch_phys_wc_add(pm2fb_fix.smem_start,
+							  pm2fb_fix.smem_len);
 	info->fbops		= &pm2fb_ops;
 	info->fix		= pm2fb_fix;
@@ -1733,12 +1721,7 @@ static void pm2fb_remove(struct pci_dev *pdev)
 	struct pm2fb_par *par = info->par;
-	if (par->mtrr_handle >= 0)
-		mtrr_del(par->mtrr_handle, info->fix.smem_start,
-			 info->fix.smem_len);
-#endif /* CONFIG_MTRR */
+	arch_phys_wc_del(par->wc_cookie);
 	release_mem_region(fix->smem_start, fix->smem_len);
@@ -1791,10 +1774,8 @@ static int __init pm2fb_setup(char *options)
 			lowvsync = 1;
 		else if (!strncmp(this_opt, "hwcursor=", 9))
 			hwcursor = simple_strtoul(this_opt + 9, NULL, 0);
 		else if (!strncmp(this_opt, "nomtrr", 6))
 			nomtrr = 1;
 		else if (!strncmp(this_opt, "noaccel", 7))
 			noaccel = 1;
@@ -1847,10 +1828,8 @@ MODULE_PARM_DESC(noaccel, "Disable acceleration");
 module_param(hwcursor, int, 0644);
 MODULE_PARM_DESC(hwcursor, "Enable hardware cursor "
 			"(1=enable, 0=disable, default=1)");
 module_param(nomtrr, bool, 0);
 MODULE_PARM_DESC(nomtrr, "Disable MTRR support (0 or 1=disabled) (default=0)");
 MODULE_AUTHOR("Jim Hague <>");
 MODULE_DESCRIPTION("Permedia2 framebuffer device driver");