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[media] em28xx: properly implement AC97 wait code 

Instead of assuming that msleep() is precise, use a jiffies
based code to wait for AC97 to be available.

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Mauro Carvalho Chehab 2013-12-27 00:28:57 -03:00
parent 2276bf70a7
commit 5022a20886
2 changed files with 8 additions and 2 deletions
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7
drivers/media/usb/em28xx/em28xx-core.c
View File

@ -23,6 +23,7 @@
*/
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/slab.h>
@ -252,16 +253,18 @@ EXPORT_SYMBOL_GPL(em28xx_toggle_reg_bits);
*/
static int em28xx_is_ac97_ready(struct em28xx *dev)
{
int ret, i;
unsigned long timeout = jiffies + msecs_to_jiffies(EM28XX_AC97_XFER_TIMEOUT);
int ret;
/* Wait up to 50 ms for AC97 command to complete */
for (i = 0; i < 10; i++, msleep(5)) {
while (time_is_after_jiffies(timeout)) {
ret = em28xx_read_reg(dev, EM28XX_R43_AC97BUSY);
if (ret < 0)
return ret;
if (!(ret & 0x01))
return 0;
msleep(5);
}
em28xx_warn("AC97 command still being executed: not handled properly!\n");

3
drivers/media/usb/em28xx/em28xx.h
View File

@ -186,6 +186,9 @@
/* time in msecs to wait for i2c writes to finish */
#define EM2800_I2C_XFER_TIMEOUT 20
/* time in msecs to wait for AC97 xfers to finish */
#define EM28XX_AC97_XFER_TIMEOUT 100
/* max. number of button state polling addresses */
#define EM28XX_NUM_BUTTON_ADDRESSES_MAX 5