Re: [PATCH 1/5] media: add media token device resource framework

Shuah Khan
2014-09-24T13:56:47Z

On 09/24/2014 05:26 AM, Hans Verkuil wrote:
> Hi Shuah,
>
> Here is my review...
>
> On 09/22/2014 05:00 PM, Shuah Khan wrote:
>> Add media token device resource framework to allow sharing
>> resources such as tuner, dma, audio etc. across media drivers
>> and non-media sound drivers that control media hardware. The
>> Media token resource is created at the main struct device that
>> is common to all drivers that claim various pieces of the main
>> media device, which allows them to find the resource using the
>> main struct device. As an example, digital, analog, and
>> snd-usb-audio drivers can use the media token resource API
>> using the main struct device for the interface the media device
>> is attached to.
>>
>> The media token resource contains token for tuner, dma, and
>> audio.
>
> Why dma and audio? Neither is being used in this patch series. I
> would leave them out until you actually show how they are used in a
> driver.

Yeah I can remove these. I am not using them in this series.

>> +static int __media_get_tkn(struct media_tkn *tkn,
>> + enum media_tkn_mode mode, bool exclusive)
>> +{
>> + int rc = 0;
>> +
>> + spin_lock(&tkn->lock);
>> + if (tkn->is_exclusive)
>> + rc = -EBUSY;
>> + else if (tkn->owners && ((mode != tkn->mode) || exclusive))
>> + rc = -EBUSY;
>> + else {
>> + if (tkn->owners < INT_MAX)
>> + tkn->owners++;
>> + else
>> + tkn->owners = 1;
>
> Somewhat weird. Can owners ever become INT_MAX?
>

I didn't have this at first. I was testing with tvtime and
noticed the count going up to 40k+ while it is streaming.
The count kept going up. So I figured I might as well add
the check to cover for cases where application like tvtime
run for a very longtime like a couple of hours.

thanks,
-- Shuah

--
Shuah Khan
Sr. Linux Kernel Developer
Samsung Research America (Silicon Valley)
shuahkh@osg.samsung.com | (970) 217-8978