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[0/6] UVC Gadget: Extend color matching support

Message ID 20221213083736.2284536-1-dan.scally@ideasonboard.com
Headers show
Series UVC Gadget: Extend color matching support | expand

Message

Daniel Scally Dec. 13, 2022, 8:37 a.m. UTC
The current UVC gadget implementation hardcodes a single color matching
descriptor and transmits it a single time following all the format and frame
descriptors. This is inflexible, and additionally applies only to the _last_
format in the array of descriptors.

This series extends the support such that the default descriptor can be amended
and is transmitted once-per-format instead of once-only, it then adds the ability
to create new color matching descriptors and associate them with particular formats.
The default color matching descriptor is retained and used where the user does not
link a new color matching descriptor to the format, so the default interaction
with userspace is unchanged from the current implementation.

Daniel Scally (6):
  usb: gadget: usb: Remove "default" from color matching attributes
  usb: gadget: uvc: Add struct for color matching in configs
  usb: gadget: uvc: Copy color matching descriptor for each frame
  usb: gadget: uvc: Remove the hardcoded default color matching
  usb: gadget: uvc: Make color matching attributes read/write
  usb: gadget: uvc: Allow creating new color matching descriptors

 .../ABI/testing/configfs-usb-gadget-uvc       |   6 +-
 drivers/usb/gadget/function/f_uvc.c           |   9 -
 drivers/usb/gadget/function/u_uvc.h           |   1 -
 drivers/usb/gadget/function/uvc_configfs.c    | 247 +++++++++++++++---
 drivers/usb/gadget/function/uvc_configfs.h    |   9 +
 5 files changed, 228 insertions(+), 44 deletions(-)

Comments

Laurent Pinchart Dec. 18, 2022, 6:12 p.m. UTC | #1
Hi Dan,

Thank you for the series.

On Tue, Dec 13, 2022 at 08:37:30AM +0000, Daniel Scally wrote:
> The current UVC gadget implementation hardcodes a single color matching
> descriptor and transmits it a single time following all the format and frame

I'm not sure I would use "transmits" in this context.  Descriptors are
for sure transmitted over the wire, but all in one go, not as individual
units (at least within a configuration descriptor).  Maybe "includes"
would be a better term ? This is nitpicking for the cover letter, but
the comment applies more importantly to commit messages and code for the
whole series.

> descriptors. This is inflexible, and additionally applies only to the _last_
> format in the array of descriptors.
> 
> This series extends the support such that the default descriptor can be amended
> and is transmitted once-per-format instead of once-only, it then adds the ability
> to create new color matching descriptors and associate them with particular formats.
> The default color matching descriptor is retained and used where the user does not
> link a new color matching descriptor to the format, so the default interaction
> with userspace is unchanged from the current implementation.

I wonder if we shouldn't drop the default descriptor. If userspace
doesn't specify one, then we really can't know what colorimetry data
applies to the frames. Instead of providing a default to the host, not
providing any colorimetry information would be better.

> Daniel Scally (6):
>   usb: gadget: usb: Remove "default" from color matching attributes
>   usb: gadget: uvc: Add struct for color matching in configs
>   usb: gadget: uvc: Copy color matching descriptor for each frame
>   usb: gadget: uvc: Remove the hardcoded default color matching
>   usb: gadget: uvc: Make color matching attributes read/write
>   usb: gadget: uvc: Allow creating new color matching descriptors
> 
>  .../ABI/testing/configfs-usb-gadget-uvc       |   6 +-
>  drivers/usb/gadget/function/f_uvc.c           |   9 -
>  drivers/usb/gadget/function/u_uvc.h           |   1 -
>  drivers/usb/gadget/function/uvc_configfs.c    | 247 +++++++++++++++---
>  drivers/usb/gadget/function/uvc_configfs.h    |   9 +
>  5 files changed, 228 insertions(+), 44 deletions(-)