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block/ps3: fix slow VRAM IO

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The current PS3 VRAM driver uses msleep() to wait for completion of RSX
DMA transfers between system memory and VRAM.  Depending on the system
timing, the processing delay and overhead of this msleep() call can
significantly impact VRAM driver IO.

To avoid the condition, add a short duration (200 usec max) udelay()
polling loop before entering the msleep() polling loop.

Signed-off-by: Hideyuki Sasaki <xhide@rd.scei.sony.co.jp>
Signed-off-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: Jim Paris <jim@jtan.com>
Cc: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Hideyuki Sasaki 2009-11-04 09:09:28 +01:00 committed by Jens Axboe
parent e00ef79971
commit f21121cde6
1 changed files with 9 additions and 1 deletions
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10
drivers/block/ps3vram.c
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@ -123,7 +123,15 @@ static int ps3vram_notifier_wait(struct ps3_system_bus_device *dev,
{
struct ps3vram_priv *priv = ps3_system_bus_get_drvdata(dev);
u32 *notify = ps3vram_get_notifier(priv->reports, NOTIFIER);
unsigned long timeout = jiffies + msecs_to_jiffies(timeout_ms);
unsigned long timeout;
for (timeout = 20; timeout; timeout--) {
if (!notify[3])
return 0;
udelay(10);
}
timeout = jiffies + msecs_to_jiffies(timeout_ms);
do {
if (!notify[3])