Em Sun, 05 Jan 2014 12:19:41 +0100
Frank Schäfer <fschaefer.oss@xxxxxxxxxxxxxx> escreveu:
> 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.
Ok.
> 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.
Yes. I was also hoping that would make the code more reliable, as
there are some issues with audio here (with usb 3.0 and with xawtv
when trying to maximize the window).
> But that should be solved with a single sleep before accessing the AC97
> chip for the first time instead ?!
Maybe. I'll try it.
> > /* max. number of button state polling addresses */
> > #define EM28XX_NUM_BUTTON_ADDRESSES_MAX 5
> >
>
--
Cheers,
Mauro
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