[PATCH 0/5] media: Allwinner A10 CSI support

Maxime Ripard
2018-11-15T19:10:31Z

Hi,

On Wed, Nov 14, 2018 at 11:24:48AM +0800, Chen-Yu Tsai wrote:
> On Tue, Nov 13, 2018 at 4:24 PM Maxime Ripard <maxime.ripard@bootlin.com> wrote:
> > Here is a series introducing the support for the A10 (and SoCs of the same
> > generation) CMOS Sensor Interface (called CSI, not to be confused with
> > MIPI-CSI, which isn't support by that IP).
> >
> > That interface is pretty straightforward, but the driver has a few issues
> > that I wanted to bring up:
> >
> > * The only board I've been testing this with has an ov5640 sensor
> > attached, which doesn't work with the upstream driver. Copying the
> > Allwinner init sequence works though, and this is how it has been
> > tested. Testing with a second sensor would allow to see if it's an
> > issue on the CSI side or the sensor side.
> > * When starting a capture, the last buffer to capture will fail due to
> > double buffering being used, and we don't have a next buffer for the
> > last frame. I'm not sure how to deal with that though. It seems like
> > some drivers use a scratch buffer in such a case, some don't care, so
> > I'm not sure which solution should be preferred.
> > * We don't have support for the ISP at the moment, but this can be added
> > eventually.
> >
> > * How to model the CSI module clock isn't really clear to me. It looks
> > like it goes through the CSI controller and then is muxed to one of the
> > CSI pin so that it can clock the sensor. I'm not quite sure how to
> > model it, if it should be a clock, the CSI driver being a clock
> > provider, or if the sensor should just use the module clock directly.
>
> Which clock are you talking about? MCLK? This seems to be fed directly from
> the CCU, as there doesn't seem to be controls for it within the CSI hardware
> block, and the diagram doesn't list it either. IMO you don't have to model it.
> The camera sensor device node would just take a reference to it directly.

Yeah, that what I went for, I guess we agree :)

> You would probably enable the (separate) pinmux setting in the CSI
> controller node.

I'll change that.

Thanks!
Maxime

--
Maxime Ripard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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