Commit 4edcd2ab authored by Luis R. Rodriguez's avatar Luis R. Rodriguez Committed by Ingo Molnar

drivers/video/fbdev/s3fb: Use arch_phys_wc_add() and pci_iomap_wc()

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(). 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
   de33c442 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 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_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);
Signed-off-by: default avatarLuis R. Rodriguez <>
Signed-off-by: default avatarBorislav Petkov <>
Acked-by: default avatarTomi Valkeinen <>
Cc: Andrew Morton <>
Cc: Andy Lutomirski <>
Cc: Antonino Daplas <>
Cc: Arnd Bergmann <>
Cc: Daniel Vetter <>
Cc: Dave Airlie <>
Cc: Geert Uytterhoeven <>
Cc: H. Peter Anvin <>
Cc: Jean-Christophe Plagniol-Villard <>
Cc: Jingoo Han <>
Cc: Juergen Gross <>
Cc: Lad, Prabhakar <>
Cc: Linus Torvalds <>
Cc: Peter Zijlstra <>
Cc: Rickard Strandqvist <>
Cc: Suresh Siddha <>
Cc: Thomas Gleixner <>
Link: default avatarIngo Molnar <>
parent c823a48a
......@@ -28,13 +28,9 @@
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
#include <asm/mtrr.h>
struct s3fb_info {
int chip, rev, mclk_freq;
int mtrr_reg;
int wc_cookie;
struct vgastate state;
struct mutex open_lock;
unsigned int ref_count;
......@@ -154,11 +150,7 @@ static const struct svga_timing_regs s3_timing_regs = {
static char *mode_option;
static int mtrr = 1;
static int fasttext = 1;
......@@ -170,11 +162,8 @@ module_param(mode_option, charp, 0444);
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)");
module_param(mtrr, int, 0444);
MODULE_PARM_DESC(mtrr, "Enable write-combining with MTRR (1=enable, 0=disable, default=1)");
module_param(fasttext, int, 0644);
MODULE_PARM_DESC(fasttext, "Enable S3 fast text mode (1=enable, 0=disable, default=1)");
......@@ -1168,7 +1157,7 @@ static int s3_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
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");
......@@ -1365,12 +1354,9 @@ static int s3_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
/* Record a reference to the driver data */
pci_set_drvdata(dev, info);
if (mtrr) {
par->mtrr_reg = -1;
par->mtrr_reg = mtrr_add(info->fix.smem_start, info->fix.smem_len, MTRR_TYPE_WRCOMB, 1);
if (mtrr)
par->wc_cookie = arch_phys_wc_add(info->fix.smem_start,
return 0;
......@@ -1405,14 +1391,7 @@ static void s3_pci_remove(struct pci_dev *dev)
if (info) {
par = info->par;
if (par->mtrr_reg >= 0) {
mtrr_del(par->mtrr_reg, 0, 0);
par->mtrr_reg = -1;
......@@ -1551,10 +1530,8 @@ static int __init s3fb_setup(char *options)
if (!*opt)
else if (!strncmp(opt, "mtrr:", 5))
mtrr = simple_strtoul(opt + 5, NULL, 0);
else if (!strncmp(opt, "fasttext:", 9))
fasttext = simple_strtoul(opt + 9, NULL, 0);
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