Re: [PATCH v2] media/doc: Allow sizeimage to be set by v4l clients

From: Stanimir Varbanov
Date: Thu May 16 2019 - 04:11:10 EST

Hi Hans,

On 5/14/19 11:54 AM, Hans Verkuil wrote:
> Hi Stanimir,
> On 4/12/19 5:59 PM, Stanimir Varbanov wrote:
>> This changes v4l2_pix_format and v4l2_plane_pix_format sizeimage
>> field description to allow v4l clients to set bigger image size
>> in case of variable length compressed data.
> I've been reconsidering this change. The sizeimage value in the format
> is the minimum size a buffer should have in order to store the data of
> an image of the width and height as described in the format.
> But there is nothing that prevents userspace from calling VIDIOC_CREATEBUFS
> instead of VIDIOC_REQBUFS to allocate larger buffers.

Sometimes CREATEBUFS cannot be implemented for a particular fw/hw.

CC: Tomasz for his opinion.

> So do we really need this change?
> The more I think about this, the more uncomfortable I become with this change.
> Regards,
> Hans