[RESEND,v2,2/8] media: uvc: Allow quirking by entity guid

When an IP is shared by multiple devices its erratas will be shared by
all of them. Instead of creating a long list of device quirks, or
waiting for the users to report errors in their hardware lets add a
routine to add quirks based on the entity guid.

Tested-by: HungNien Chen <hn.chen@sunplusit.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 drivers/media/usb/uvc/uvc_driver.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

Hi Ricardo,

Thank you for the patch.


On Fri, Dec 02, 2022 at 06:02:42PM +0100, Ricardo Ribalda wrote:
> When an IP is shared by multiple devices its erratas will be shared by
> all of them. Instead of creating a long list of device quirks, or
> waiting for the users to report errors in their hardware lets add a
> routine to add quirks based on the entity guid.

I'm not thrilled by this. An entity is not an "IP". Quirks are needed to
handle issues with particular firmware versions on particular devices.
The same entity GUID can be used by different devices running different
firmware versions, some that would require a quirk and some that
wouldn't.

> Tested-by: HungNien Chen <hn.chen@sunplusit.com>
> Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> ---
>  drivers/media/usb/uvc/uvc_driver.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> index 9c05776f11d1..c63ecfd4617d 100644
> --- a/drivers/media/usb/uvc/uvc_driver.c
> +++ b/drivers/media/usb/uvc/uvc_driver.c
> @@ -1493,6 +1493,28 @@ static int uvc_parse_control(struct uvc_device *dev)
>  	return 0;
>  }
>  
> +static const struct uvc_entity_quirk {
> +	u8 guid[16];
> +	u32 quirks;
> +} uvc_entity_quirk[] = {
> +};
> +
> +static void uvc_entity_quirks(struct uvc_device *dev)
> +{
> +	struct uvc_entity *entity;
> +	int i;

unsigned int

> +
> +	list_for_each_entry(entity, &dev->entities, list) {
> +		for (i = 0; i < ARRAY_SIZE(uvc_entity_quirk); i++) {
> +			if (memcmp(entity->guid, uvc_entity_quirk[i].guid,
> +				   sizeof(entity->guid)) == 0) {
> +				dev->quirks |= uvc_entity_quirk[i].quirks;
> +				break;
> +			}
> +		}
> +	}
> +}
> +
>  /* -----------------------------------------------------------------------------
>   * Privacy GPIO
>   */
> @@ -2452,6 +2474,9 @@ static int uvc_probe(struct usb_interface *intf,
>  		goto error;
>  	}
>  
> +	/* Apply entity based quirks */
> +	uvc_entity_quirks(dev);
> +
>  	dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
>  		 dev->uvc_version >> 8, dev->uvc_version & 0xff,
>  		 udev->product ? udev->product : "<unnamed>",
>

Hi Laurent

On Fri, 30 Dec 2022 at 14:40, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
>
> On Fri, Dec 02, 2022 at 06:02:42PM +0100, Ricardo Ribalda wrote:
> > When an IP is shared by multiple devices its erratas will be shared by
> > all of them. Instead of creating a long list of device quirks, or
> > waiting for the users to report errors in their hardware lets add a
> > routine to add quirks based on the entity guid.
>
> I'm not thrilled by this. An entity is not an "IP". Quirks are needed to
> handle issues with particular firmware versions on particular devices.
> The same entity GUID can be used by different devices running different
> firmware versions, some that would require a quirk and some that
> wouldn't.

Unfortunately there are ISPs that do not support firmware upgrading
that have an error on their firmware (or in this particular case a
different interpretation of the standard). Those ISPs are mounted in
different boards with a VID:PID that is chosen by the module
manufacturer.
In those cases we cannot get a list of the devices that are broken, we
could only get a sublist that we will keep updating indefinitely as
users keep reporting bugs (if they do so).

We are lucky enough that SunplusIT has been very active and provided
us a way to detect what hardware requires quirking. In those
situations where the vendor is on board and there is no upgrade
mechanism I think that this is a good compromise.

>
> > Tested-by: HungNien Chen <hn.chen@sunplusit.com>
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c | 25 +++++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index 9c05776f11d1..c63ecfd4617d 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -1493,6 +1493,28 @@ static int uvc_parse_control(struct uvc_device *dev)
> >       return 0;
> >  }
> >
> > +static const struct uvc_entity_quirk {
> > +     u8 guid[16];
> > +     u32 quirks;
> > +} uvc_entity_quirk[] = {
> > +};
> > +
> > +static void uvc_entity_quirks(struct uvc_device *dev)
> > +{
> > +     struct uvc_entity *entity;
> > +     int i;
>
> unsigned int
>
> > +
> > +     list_for_each_entry(entity, &dev->entities, list) {
> > +             for (i = 0; i < ARRAY_SIZE(uvc_entity_quirk); i++) {
> > +                     if (memcmp(entity->guid, uvc_entity_quirk[i].guid,
> > +                                sizeof(entity->guid)) == 0) {
> > +                             dev->quirks |= uvc_entity_quirk[i].quirks;
> > +                             break;
> > +                     }
> > +             }
> > +     }
> > +}
> > +
> >  /* -----------------------------------------------------------------------------
> >   * Privacy GPIO
> >   */
> > @@ -2452,6 +2474,9 @@ static int uvc_probe(struct usb_interface *intf,
> >               goto error;
> >       }
> >
> > +     /* Apply entity based quirks */
> > +     uvc_entity_quirks(dev);
> > +
> >       dev_info(&dev->udev->dev, "Found UVC %u.%02x device %s (%04x:%04x)\n",
> >                dev->uvc_version >> 8, dev->uvc_version & 0xff,
> >                udev->product ? udev->product : "<unnamed>",
> >
>
> --
> Regards,
>
> Laurent Pinchart