On 09/01/14 17:36, Hans de Goede wrote:
> Hi,
>
> On 09/01/2014 03:29 PM, Hans Verkuil wrote:
>> Hi Hans,
>>
>> At first glance this looks fine. But making changes in videobuf is always
>> scary :-)
>> so I hope Marek can look at this as well.
>>
>> How well was this tested?
>
> I ran some tests on bttv which all ran well.
>
> Note that the code already allowed for going from say 4 buffers to 1,
> and the old code path for reqbufs was already calling __videobuf_free()
> before re-allocating the buffers again. So in essence this just changes
> things to allow the 4 buffers to 1 case to also be 4 buffers to 0.
The code looks good and I've tested it with cx88 which worked (well, except
for the zillion other bugs in cx88, but that's another story). I do want to
do a few more tests on Friday, though. This time with a more stable driver.
I think we should consider adding this to the stable tree as well.
Regards,
Hans
>
> Regards,
>
> Hans
>
>
>>
>> I'll try do test this as well.
>>
>> Regards,
>>
>> Hans
>>
>> On 08/31/2014 12:19 PM, Hans de Goede wrote:
>>> All the infrastructure for this is already there, and despite our desires
>>> for
>>> the old videobuf code to go away, it is currently still in use in 18
>>> drivers.
>>>
>>> Allowing reqbufs(0) makes these drivers behave consistent with modern
>>> drivers,
>>> making live easier for userspace, see e.g. :
>>> https://bugzilla.gnome.org/show_bug.cgi?id=735660
>>>
>>> Signed-off-by: Hans de Goede <hdego...@redhat.com>
>>> ---
>>> drivers/media/v4l2-core/videobuf-core.c | 11 ++++++-----
>>> 1 file changed, 6 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/media/v4l2-core/videobuf-core.c
>>> b/drivers/media/v4l2-core/videobuf-core.c
>>> index fb5ee5d..b91a266 100644
>>> --- a/drivers/media/v4l2-core/videobuf-core.c
>>> +++ b/drivers/media/v4l2-core/videobuf-core.c
>>> @@ -441,11 +441,6 @@ int videobuf_reqbufs(struct videobuf_queue *q,
>>> unsigned int size, count;
>>> int retval;
>>>
>>> - if (req->count < 1) {
>>> - dprintk(1, "reqbufs: count invalid (%d)\n", req->count);
>>> - return -EINVAL;
>>> - }
>>> -
>>> if (req->memory != V4L2_MEMORY_MMAP &&
>>> req->memory != V4L2_MEMORY_USERPTR &&
>>> req->memory != V4L2_MEMORY_OVERLAY) {
>>> @@ -471,6 +466,12 @@ int videobuf_reqbufs(struct videobuf_queue *q,
>>> goto done;
>>> }
>>>
>>> + if (req->count == 0) {
>>> + dprintk(1, "reqbufs: count invalid (%d)\n", req->count);
>>> + retval = __videobuf_free(q);
>>> + goto done;
>>> + }
>>> +
>>> count = req->count;
>>> if (count > VIDEO_MAX_FRAME)
>>> count = VIDEO_MAX_FRAME;
>>>
>>
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