On 02/18/15 10:42, Kamil Debski wrote: > Hi Hans, > >> From: Hans Verkuil [mailto:hverkuil@xxxxxxxxx] >> Sent: Tuesday, February 17, 2015 10:11 AM >> >> Hi Kamil, >> >> On 12/16/14 12:36, Kamil Debski wrote: >>> The vb2: fix bytesused == 0 handling (8a75ffb) patch changed the >>> behavior of __fill_vb2_buffer function, so that if bytesused is 0 it >>> is set to the size of the buffer. However, bytesused set to 0 is used >>> by older codec drivers as as indication used to mark the end of >> stream. >>> >>> To keep backward compatibility, this patch adds a flag passed to the >>> vb2_queue_init function - VB2_FILEIO_ALLOW_ZERO_BYTESUSED. If the >> flag >>> is set upon initialization of the queue, the videobuf2 keeps the >> value >>> of bytesused intact and passes it to the driver. >> >> What is the status of this patch series? > > I have to admit that I had forgotten a bit about this patch, because of > other > important work. Thanks for reminding me :) > >> Note that io_flags is really the wrong place for this flag, it should >> be io_modes. This flag has nothing to do with file I/O. > > What do you think about adding a separate flags field into the vb2_queue > structure? This could be combined with changing io_flags to u8 or a bit > field > to save space. I think changing io_flags to a bitfield is a good idea. unsigned fileio_read_once:1; unsigned fileio_write_immediately:1; unsigned allow_zero_bytesused:1; However, going back to allow_zero_bytesused: this has been broken for quite some time without anyone complaining (other than you :-) ). Might it not be better to just fix this properly by calling V4L2_DEC_CMD_STOP, as done here: https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg84916.html, and drop the support for zero bytesused to mark EOS entirely? I might be too optimistic here. Or perhaps at least add a pr_warn telling users to switch to V4L2_DEC_CMD_STOP since this will be removed in 2017 or whatever. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
