[PATCH v7 2/9] video: fbdev: i740fb: use arch_phys_wc_add() and pci_ioremap_wc_bar()

From: Luis R. Rodriguez
Date: Fri Jun 19 2015 - 18:15:17 EST

From: "Luis R. Rodriguez" <mcgrof@xxxxxxxx>

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: Jingoo Han <jg1.han@xxxxxxxxxxx>
Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Cc: Benoit Taine <benoit.taine@xxxxxxx>
Cc: Suresh Siddha <sbsiddha@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Dave Airlie <airlied@xxxxxxxxxx>
Cc: Antonino Daplas <adaplas@xxxxxxxxx>
Cc: Jean-Christophe Plagniol-Villard <plagnioj@xxxxxxxxxxxx>
Cc: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Cc: linux-fbdev@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Acked-by: Tomi Valkeinen <tomi.valkeinen@xxxxxx>
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxx>
drivers/video/fbdev/i740fb.c | 35 ++++++-----------------------------
1 file changed, 6 insertions(+), 29 deletions(-)

diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c
index a2b4204..452e116 100644
--- a/drivers/video/fbdev/i740fb.c
+++ b/drivers/video/fbdev/i740fb.c
@@ -27,24 +27,15 @@
#include <linux/console.h>
#include <video/vga.h>

-#include <asm/mtrr.h>
#include "i740_reg.h"

static char *mode_option;
static int mtrr = 1;

struct i740fb_par {
unsigned char __iomem *regs;
bool has_sgram;
- int mtrr_reg;
+ int wc_cookie;
bool ddc_registered;
struct i2c_adapter ddc_adapter;
struct i2c_algo_bit_data ddc_algo;
@@ -1040,7 +1031,7 @@ static int i740fb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
goto err_request_regions;

- info->screen_base = pci_ioremap_bar(dev, 0);
+ info->screen_base = pci_ioremap_wc_bar(dev, 0);
if (!info->screen_base) {
dev_err(info->device, "error remapping base\n");
ret = -ENOMEM;
@@ -1144,13 +1135,9 @@ static int i740fb_probe(struct pci_dev *dev, const struct pci_device_id *ent)

fb_info(info, "%s frame buffer device\n", info->fix.id);
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;

@@ -1177,13 +1164,7 @@ static void i740fb_remove(struct pci_dev *dev)

if (info) {
struct i740fb_par *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);
if (par->ddc_registered)
@@ -1287,10 +1268,8 @@ static int __init i740fb_setup(char *options)
while ((opt = strsep(&options, ",")) != NULL) {
if (!*opt)
else if (!strncmp(opt, "mtrr:", 5))
mtrr = simple_strtoul(opt + 5, NULL, 0);
mode_option = opt;
@@ -1327,7 +1306,5 @@ MODULE_DESCRIPTION("fbdev driver for Intel740");
module_param(mode_option, charp, 0444);
MODULE_PARM_DESC(mode_option, "Default video mode ('640x480-8@60', etc)");

module_param(mtrr, int, 0444);
MODULE_PARM_DESC(mtrr, "Enable write-combining with MTRR (1=enable, 0=disable, default=1)");

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