Re: [PATCH v2] usb: gadget: uvc: Add H264 frame format support

[AKASH KUMAR]

On 7/11/2024 2:37 PM, Greg Kroah-Hartman wrote:
> On Thu, Jul 11, 2024 at 01:53:04PM +0530, Akash Kumar wrote:
> > Add support for framebased frame format which can be used to support
> > multiple formats like H264 or H265 other than mjpeg and YUV frames.
> >
> > Framebased format is set to H264 by default, which can be updated to
> > other formats by updating the GUID through guid configfs attribute.
> > Using Different structures for all 3 formats as H264 has different
> > structure than mjpeg and uncompressed which will be paased to
> > frame make func based on active format instead of common frame
> > structure, have updated all apis in driver accordingly.
> > h264 is not recognized by hosts machine during enumeration
> > with common frame structure, so we need to pass h264 frame
> > structure separately.
> >
> > Signed-off-by: Akash Kumar <quic_akakum@xxxxxxxxxxx>
> > ---
> >   .../ABI/testing/configfs-usb-gadget-uvc       |  88 ++-
> >   drivers/usb/gadget/function/uvc_configfs.c    | 570 +++++++++++++++---
> >   drivers/usb/gadget/function/uvc_configfs.h    |  34 +-
> >   drivers/usb/gadget/function/uvc_v4l2.c        |  80 ++-
> >   include/uapi/linux/usb/video.h                |  62 ++
> >   5 files changed, 714 insertions(+), 120 deletions(-)
> >
> > Changes for v2:
> > - Added H264 frame format Details in Documentation/ABI/
> >    and new configsfs attribute path for mjpeg and
> >    uncompresseed formats.
> >
> > diff --git a/Documentation/ABI/testing/configfs-usb-gadget-uvc b/Documentation/ABI/testing/configfs-usb-gadget-uvc
> > index 4feb692c4c1d..2580083cdcc5 100644
> > --- a/Documentation/ABI/testing/configfs-usb-gadget-uvc
> > +++ b/Documentation/ABI/testing/configfs-usb-gadget-uvc
> > @@ -224,13 +224,13 @@ Description:	Additional color matching descriptors
> >   					  white
> >   		========================  ======================================
> >   
> > -What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg
> > -Date:		Dec 2014
> > +What:		/config/usb-gadget/gadget/functions/uvc.name/streaming/mjpeg/name
> You are changing an existing api, how will all existing code handle 
> this? Will it not break? What is ensuring that this will work as-is ok?
> I have modified all existing apis in kernel and have handled it and 
> all existing formats
are working along with H264 in this change. Only user needs to change 
configfs parameter
path according to updated path in documentation in Userspace.Currently 
H264 doesn't work with same
structure and we need add it differently as a result these configfs 
paths are getting updated.
Daniel and Laurent can you suggest if it ok?
> > -#define UVCG_FRAME_ATTR(cname, aname, bits) \
> > -static ssize_t uvcg_frame_##cname##_show(struct config_item *item, char *page)\
> > +#define UVCG_FRAME_ATTR(cname, fname, bits) \
> > +static ssize_t uvcg_frame_##fname##_##cname##_show(struct config_item *item, char *page)\
> >   {									\
> >   	struct uvcg_frame *f = to_uvcg_frame(item);			\
> >   	struct f_uvc_opts *opts;					\
> > @@ -1936,14 +1941,14 @@ static ssize_t uvcg_frame_##cname##_show(struct config_item *item, char *page)\
> >   	opts = to_f_uvc_opts(opts_item);				\
> >   									\
> >   	mutex_lock(&opts->lock);					\
> > -	result = sprintf(page, "%u\n", f->frame.cname);			\
> > +	result = scnprintf(page, PAGE_SIZE, "%u\n", f->frame.fname.cname);\
> sysfs_emit() is made for this.

Sure, will change.


Thanks,
Akash