drivers/video/fbdev/arkfb.c: Use arch_phys_wc_add() and pci_iomap_wc()

Convert the driver from using the x86-specific MTRR code to the
architecture-agnostic arch_phys_wc_add(). It will avoid MTRRs if
write-combining is available. In order to take advantage of that
also ensure the ioremapped 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 it is being 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
pci_mmap_page_range()").

The conversion done is expressed by the following Coccinelle
SmPL patch, it additionally required manual intervention to
address all the ifdeffery 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);
+arch_phys_wc_del(index);

@ mtrr_rm_zero_arg depends on mtrr_found @
expression mtrr_found.index;
@@

-mtrr_del(index, 0, 0);
+arch_phys_wc_del(index);

@ 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);
+arch_phys_wc_del(index);

@ 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);

Signed-off-by: Luis R. Rodriguez <[e-mail]>
Signed-off-by: Borislav Petkov <[e-mail]>
Acked-by: Tomi Valkeinen <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Antonino Daplas <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Jean-Christophe Plagniol-Villard <[e-mail]>
Cc: Juergen Gross <[e-mail]>
Cc: Lad, Prabhakar <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Suresh Siddha <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

drivers/video/fbdev/arkfb.c

···
 #include <linux/console.h> /* Why should fb driver call console functions? because console_lock() */
 #include <video/vga.h>
 
-#ifdef CONFIG_MTRR
-#include <asm/mtrr.h>
-#endif
-
 struct arkfb_info {
 	int mclk_freq;
-	int mtrr_reg;
+	int wc_cookie;
 
 	struct dac_info *dac;
 	struct vgastate state;
···
 
 static char *mode_option = "640x480-8@60";
 
-#ifdef CONFIG_MTRR
-static int mtrr = 1;
-#endif
-
 MODULE_AUTHOR("(c) 2007 Ondrej Zajicek <[e-mail]>");
 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("fbdev driver for ARK 2000PV");
···
 MODULE_PARM_DESC(mode_option, "Default video mode ('640x480-8@60', etc)");
 module_param_named(mode, mode_option, charp, 0444);
 MODULE_PARM_DESC(mode, "Default video mode ('640x480-8@60', etc) (deprecated)");
-
-#ifdef CONFIG_MTRR
-module_param(mtrr, int, 0444);
-MODULE_PARM_DESC(mtrr, "Enable write-combining with MTRR (1=enable, 0=disable, default=1)");
-#endif
 
 static int threshold = 4;
 
···
 	info->fix.smem_len = pci_resource_len(dev, 0);
 
 	/* Map physical IO memory address into kernel space */
-	info->screen_base = pci_iomap(dev, 0, 0);
+	info->screen_base = pci_iomap_wc(dev, 0, 0);
 	if (! info->screen_base) {
 		rc = -ENOMEM;
 		dev_err(info->device, "iomap for framebuffer failed\n");
···
 
 	/* Record a reference to the driver data */
 	pci_set_drvdata(dev, info);
-
-#ifdef CONFIG_MTRR
-	if (mtrr) {
-		par->mtrr_reg = -1;
-		par->mtrr_reg = mtrr_add(info->fix.smem_start, info->fix.smem_len, MTRR_TYPE_WRCOMB, 1);
-	}
-#endif
-
+	par->wc_cookie = arch_phys_wc_add(info->fix.smem_start,
+					  info->fix.smem_len);
 	return 0;
 
 	/* Error handling */
···
 
 	if (info) {
 		struct arkfb_info *par = info->par;
-
-#ifdef CONFIG_MTRR
-		if (par->mtrr_reg >= 0) {
-			mtrr_del(par->mtrr_reg, 0, 0);
-			par->mtrr_reg = -1;
-		}
-#endif
-
+		arch_phys_wc_del(par->wc_cookie);
 		dac_release(par->dac);
 		unregister_framebuffer(info);
 		fb_dealloc_cmap(&info->cmap);