Re: [PATCH v5 0/5] Add OV5640 parallel interface and RGB565/YUYV support

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Hi Maxime,

On Wed, 10 Jan 2018 16:37:24 +0100
Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote:

> Hi Hugues,
> 
> On Mon, Jan 08, 2018 at 05:13:39PM +0000, Hugues FRUCHET wrote:
> > I'm using a ST board with OV5640 wired in parallel bus output in order 
> > to interface to my STM32 DCMI parallel interface.
> > Perhaps could you describe your setup so I could help on understanding 
> > the problem on your side. From my past experience with this sensor 
> > module, you can first check hsync/vsync polarities, the datasheet is 
> > buggy on VSYNC polarity as documented in patch 4/5.
> 
> It turns out that it was indeed a polarity issue.
> 
> It looks like that in order to operate properly, I need to setup the
> opposite polarity on HSYNC and VSYNC on the interface. I looked at the
> signals under a scope, and VSYNC is obviously inversed as you
> described. HSYNC, I'm not so sure since the HBLANK period seems very
> long, almost a line.
> 
> Since VSYNC at least looks correct, I'd be inclined to think that the
> polarity is inversed on at least the SoC I'm using it on.
> 
> Yong, did you test the V3S CSI driver with a parallel interface? With
> what sensor driver? Have you found some polarities issues like this?

Did you try it with Allwinner SoCs?

No. I only tested with a BT1120 signal generated by FPGA or ADV7611. HSYNC
and VSYNC are not used.

For V3s CSI driver, I will add the following to dt-bindings:
Endpoint node properties for CSI1
---------------------------------

- remote-endpoint      : (required) a phandle to the bus receiver's endpoint
                          node
- bus-width:           : (required) must be 8, 10, 12 or 16
- pclk-sample          : (optional) (default: sample on falling edge)
- hsync-active         : (only required for parallel)
- vsync-active         : (only required for parallel)

You could try diffrent hsync-active/vsync-active values here.

> 
> Thanks!
> Maxime
> 
> -- 
> Maxime Ripard, Free Electrons
> Embedded Linux and Kernel engineering
> http://free-electrons.com


Thanks,
Yong



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