[tip:x86/mm] drivers/video/fbdev/vt8623fb: Use arch_phys_wc_add() and pci_iomap_wc()

From: tip-bot for Luis R. Rodriguez
Date: Tue Aug 25 2015 - 04:26:50 EST

Commit-ID: 81bdef04d3bc76fc516ca613fa96061ff27bced9
Gitweb: http://git.kernel.org/tip/81bdef04d3bc76fc516ca613fa96061ff27bced9
Author: Luis R. Rodriguez <mcgrof@xxxxxxxx>
AuthorDate: Mon, 24 Aug 2015 12:13:30 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 25 Aug 2015 09:59:45 +0200

drivers/video/fbdev/vt8623fb: 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
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 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: Luis R. Rodriguez <mcgrof@xxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Antonino Daplas <adaplas@xxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
Cc: Jingoo Han <jg1.han@xxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Suresh Siddha <sbsiddha@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: airlied@xxxxxxxx
Cc: benh@xxxxxxxxxxxxxxxxxxx
Cc: bhelgaas@xxxxxxxxxx
Cc: dan.j.williams@xxxxxxxxx
Cc: konrad.wilk@xxxxxxxxxx
Cc: linux-fbdev@xxxxxxxxxxxxxxx
Cc: linux-pci@xxxxxxxxxxxxxxx
Cc: mst@xxxxxxxxxx
Cc: toshi.kani@xxxxxx
Cc: vinod.koul@xxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/1440443613-13696-9-git-send-email-mcgrof@xxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
drivers/video/fbdev/vt8623fb.c | 31 ++++++-------------------------
1 file changed, 6 insertions(+), 25 deletions(-)

diff --git a/drivers/video/fbdev/vt8623fb.c b/drivers/video/fbdev/vt8623fb.c
index 8bac309..dd0f18e 100644
--- a/drivers/video/fbdev/vt8623fb.c
+++ b/drivers/video/fbdev/vt8623fb.c
@@ -26,13 +26,9 @@
#include <linux/console.h> /* Why should fb driver call console functions? because console_lock() */
#include <video/vga.h>

-#include <asm/mtrr.h>
struct vt8623fb_info {
char __iomem *mmio_base;
- int mtrr_reg;
+ int wc_cookie;
struct vgastate state;
struct mutex open_lock;
unsigned int ref_count;
@@ -99,10 +95,7 @@ static struct svga_timing_regs vt8623_timing_regs = {
/* Module parameters */

static char *mode_option = "640x480-8@60";
static int mtrr = 1;

MODULE_AUTHOR("(c) 2006 Ondrej Zajicek <santiago@xxxxxxxxxxxxx>");
@@ -112,11 +105,8 @@ module_param(mode_option, charp, 0644);
MODULE_PARM_DESC(mode_option, "Default video mode ('640x480-8@60', etc)");
module_param_named(mode, mode_option, charp, 0);
MODULE_PARM_DESC(mode, "Default video mode e.g. '648x480-8@60' (deprecated)");
module_param(mtrr, int, 0444);
MODULE_PARM_DESC(mtrr, "Enable write-combining with MTRR (1=enable, 0=disable, default=1)");

/* ------------------------------------------------------------------------- */
@@ -710,7 +700,7 @@ static int vt8623_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
info->fix.mmio_len = pci_resource_len(dev, 1);

/* 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");
@@ -781,12 +771,9 @@ static int vt8623_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,
+ info->fix.smem_len);

return 0;

@@ -816,13 +803,7 @@ static void vt8623_pci_remove(struct pci_dev *dev)
if (info) {
struct vt8623fb_info *par = info->par;

- if (par->mtrr_reg >= 0) {
- mtrr_del(par->mtrr_reg, 0, 0);
- par->mtrr_reg = -1;
- }
+ arch_phys_wc_del(par->wc_cookie);

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/