Em 19-03-2012 19:05, Ezequiel García escreveu:
> Hi Mauro,
>
> On 3/7/12, Mauro Carvalho Chehab <mchehab@xxxxxxxxxx> wrote:
>>
>> The usage of saa711x is simple. All you need to do is to implement
>> an I2C bus at your easycap driver, load the module, and then, redirect
>> any demod ioctl call to the I2C bus, like:
>>
>> static int vidioc_querystd(struct file *file, void *priv, v4l2_std_id *norm)
>> {
>> struct em28xx_fh *fh = priv;
>> struct em28xx *dev = fh->dev;
>> int rc;
>>
>> rc = check_dev(dev);
>> if (rc < 0)
>> return rc;
>>
>> v4l2_device_call_all(&dev->v4l2_dev, 0, video, querystd, norm);
>>
>> return 0;
>> }
>>
>>
>> An I2C device has an address that needs to be send through the I2C
>> bus.
>>
>> The saa711x devices use one of the I2C addresses below:
>>
>> static unsigned short saa711x_addrs[] = {
>> 0x4a >> 1, 0x48 >> 1, /* SAA7111, SAA7111A and SAA7113 */
>> 0x42 >> 1, 0x40 >> 1, /* SAA7114, SAA7115 and SAA7118 */
>> I2C_CLIENT_END };
>>
>
> I made my easycap driver use saa7115 driver to detect its saa7113 chip.
> It wasn't so hard after some head scratching.
Good!
> The problem is now modprobe is taking too long, mainly because saa7115 does
> some probing.
> I was thinking (since we already discussed deferring stuff to a workqueue):
>
> Would it be problematic (in any fashion) to do add the i2c sub device
>
> v4l2_i2c_new_subdev(&dev->v4l2_dev, &dev->i2c_adap,
> "saa7115_auto", 0, saa711x_addrs);
>
> in a workqueue, (in the same way modules are loaded in workqueues)?
>
> I think not, since we won't call i2c directly, but rather through
> v4l2_device_call_all(), right?
It would likely work. I would add some locking maybe at open or at ioctl
level, to prevent calling the device while the init doesn't finish.
Regards,
Mauro
>
> Thanks,
> Ezequiel.
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