Hi, > From: Hans Verkuil [mailto:hverkuil@xxxxxxxxx] > Sent: Wednesday, February 18, 2015 10:58 AM > > 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 :-) ). If I remember correctly, it was Nicolas who reported to me the problem on the IRC. > 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 think it would be good to have the backward compatibility for some time. > 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. Where do you see the pr_warn? I guess it would be good if it was only displayed once and only when the app uses bytesused == 0 to signal the EOS. Do you think alike? > > Regards, > > Hans Best wishes, -- Kamil Debski Samsung R&D Institute Poland -- 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
