Re: What todo with cams which have 2 drivers?

[Hans Verkuil <hverkuil@xxxxxxxxx>]

On Tuesday 26 August 2008 10:03:25 Hans de Goede wrote:
> Hi All,
> 
> Now that gspca is part of the v4l-dvb tree, we have 2 drivers for several cams.
> 
> The "problem" is that various gspca subdrivers and various drivers written by 
> Luca Risolia support the same controllers (and a subset of the same sensors too).
> 
> Currently this is solved by removing the usb-id's for any cams supported by 
> Luca's drivers (which have been in the kernel for some time) from gspca when 
> Luca's drivers are enabled.
> 
> Since the drivers written by Luca Risolia seem to be basicly unmaintained, for 
> example luca has one last update to his sn9c102 driver on his website which he 
> has never bother to merge upstream, and since Luca's drivers often have a 
> poorer feature set then gspca (no exposure control for sn9c102 + tas5110 making 
> it unusable in many lighting conditions for example), I would like to suggest 
> to start removing usb-id's from Luca's drivers when gspca is enabled and leave 
> them always enabled in gspca, atleast for those cams which have been thoroughly 
> tested with gspca.

Seems like a good idea.

> ##
> 
> Another issue is that Luca's drivers claim to support usb-id's which they don't 
> Luca uses probing to find out which sensor there is instead of using usb-id's 
> and has added all usb-id's he could find for a controller, independend on 
> wether or not his driver supports the sensor used in that usb-id.
> 
> For example the sn9c102 driver used to claim that it supports 0c45:6011 but it 
> does not, as that uses an ov6650 sensor, which the sn9c102 driver does not 
> support. I actually have such a cam and have tested it with Luca's driver and 
> that only results in the following dmesg: "No supported image sensor detected 
> for this bridge", a patch removing this usb-id has already been submitted (and 
> accepted) through the gspca tree.
> 
> I've also noticed that Luca's zc0301 driver only supports 2 sensors the pas202 
> and the pb0330, where as the gspca zc3xx driver supports 18 different sensors!
> 
> If you look in zc0301_sensor.h you will find the following list:
>          { ZC0301_USB_DEVICE(0x041e, 0x4017, 0xff), }, /* ICM105 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x401c, 0xff), }, /* PAS106 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x401e, 0xff), }, /* HV7131 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x401f, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x041e, 0x4022, 0xff), },                         \
>          { ZC0301_USB_DEVICE(0x041e, 0x4034, 0xff), }, /* PAS106 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x4035, 0xff), }, /* PAS106 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x4036, 0xff), }, /* HV7131 */            \
>          { ZC0301_USB_DEVICE(0x041e, 0x403a, 0xff), }, /* HV7131 */            \
>          { ZC0301_USB_DEVICE(0x0458, 0x7007, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x0458, 0x700c, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x0458, 0x700f, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x046d, 0x08ae, 0xff), }, /* PAS202 */            \
>          { ZC0301_USB_DEVICE(0x055f, 0xd003, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x055f, 0xd004, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x0ac8, 0x0301, 0xff), },                         \
>          { ZC0301_USB_DEVICE(0x0ac8, 0x301b, 0xff), }, /* PB-0330/HV7131 */    \
>          { ZC0301_USB_DEVICE(0x0ac8, 0x303b, 0xff), }, /* PB-0330 */           \
>          { ZC0301_USB_DEVICE(0x10fd, 0x0128, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x10fd, 0x8050, 0xff), }, /* TAS5130 */           \
>          { ZC0301_USB_DEVICE(0x10fd, 0x804e, 0xff), }, /* TAS5130 */           \
> 
> Note how most of these cams cannot work with Luca's driver as there is no 
> support for the mentioned sensors. So I'll be submitting a patch (through the 
> gspca tree) enabling these cams unconditional in gspca and removing their 
> usb-ids from Luca's zc0301 driver, given the small number of supported cams 
> then left (2), we should consider deprecating the zc0301 driver all together.

Makes also sense IMHO.

> I'll do an audit of Luca's other drivers for similar issues (claiming unsupport 
> usb-id's)

In general I am getting worried by the lack of a common standard to
interface to sensor and controller drivers. I'm no expert on webcams, so
correct me if I'm wrong, but it seems to me that the correct design would
be to have a generic API to these devices that can be used by the various
USB or platform drivers.

But for e.g. the mt9* sensors we have three that use the soc_camera
interface, one using the sn9c102 interface and I know of two more that
are not yet in v4l-dvb but that will use the v4l2-int-device.h interface.
It's a mess in my opinion.

I think it would be interesting to discuss this further with you in Portland.

Regards,

	Hans

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