Am 04.01.2014 11:55, schrieb Mauro Carvalho Chehab:
> Instead of assuming that msleep() is precise, use a jiffies
> based code to wait for AC97 to be available.
>
> Signed-off-by: Mauro Carvalho Chehab <m.chehab@xxxxxxxxxxx>
> ---
> drivers/media/usb/em28xx/em28xx-core.c | 7 +++++--
> drivers/media/usb/em28xx/em28xx.h | 5 ++++-
> 2 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
> index 818248d3fd28..36b2f1ab4474 100644
> --- a/drivers/media/usb/em28xx/em28xx-core.c
> +++ b/drivers/media/usb/em28xx/em28xx-core.c
> @@ -23,6 +23,7 @@
> */
>
> #include <linux/init.h>
> +#include <linux/jiffies.h>
> #include <linux/list.h>
> #include <linux/module.h>
> #include <linux/slab.h>
> @@ -254,16 +255,18 @@ 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(EM2800_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)) {
time_is_before_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");
> diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
> index 9d6f43e4681f..ac79501f5d9f 100644
> --- a/drivers/media/usb/em28xx/em28xx.h
> +++ b/drivers/media/usb/em28xx/em28xx.h
> @@ -182,9 +182,12 @@
>
> #define EM28XX_INTERLACED_DEFAULT 1
>
> -/* time in msecs to wait for i2c writes to finish */
> +/* time in msecs to wait for i2c xfers to finish */
> #define EM2800_I2C_XFER_TIMEOUT 20
>
> +/* time in msecs to wait for AC97 xfers to finish */
> +#define EM2800_AC97_XFER_TIMEOUT 100
> +
I applies to all chips supporting AC97 audio, so call it
EM28XX_AC97_XFER_TIMEOUT.
Why did you increase the timeout from 50ms to 100ms ?
50ms already seems to be a lot !
IIRC, the problem you are trying to fix is that the chip sometimes is
not yet ready when probing.
But that should be solved with a single sleep before accessing the AC97
chip for the first time instead ?!
> /* max. number of button state polling addresses */
> #define EM28XX_NUM_BUTTON_ADDRESSES_MAX 5
>
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