On 10/25/2013 12:33 PM, Laurent Pinchart wrote:

On Thursday 24 October 2013 23:06:18 Stephen Warren wrote:

quoted

On 10/24/2013 12:20 PM, Laurent Pinchart wrote:

...

quoted

quoted

The case I'm mostly concerned about would be two different compatibility
strings to select whether the device should be handled by a KMS or V4L
driver. I don't think that's a good idea.

I wouldn't think of the two compatible values as selecting different
specific Linux drivers, but rather they simply describe the HW in
different levels of detail. The fact that if we know a certain level of
detail about the HW means that Linux can and does create a KMS driver
rather than a V4L2 driver seems like a detail that's completely hidden
inside the OS.

I expect the same level of details to be needed on both the KMS and V4L sides. 
Taking the example of the ADV7511 HDMI transmitter, the only change in the DT 
bindings between KMS and V4L would be the compatible string. "adi,adv7511-v4l" 
and "adi,adv7511-kms" is an option that I don't really like. Renaming -v4l and 
-kms to different names wouldn't fundamentally change the problem.

Yes, two compatible values such as "adi,adv7511-v4l" and
"adi,adv7511-kms" sounds like a bad idea.

Rather, shouldn't we have just "adi,adv7511", and the driver for that
should register itself in a way that allows either/both the top-level
DRM or top-level V4L drivers to find it, and make use of its services.
There are plenty of drivers in the kernel already that export services
through two different subsystems, e.g. a GPIO HW module that registers
as both a struct gpio_chip and a struct irq_chip, or both a struct
gpio_chip and a pinctrl device.
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