Good news Maxime !
Have you seen that you can adapt the polarities through devicetree ?
+ /* Parallel bus endpoint */
+ ov5640_to_parallel: endpoint {
[...]
+ hsync-active = <0>;
+ vsync-active = <0>;
+ pclk-sample = <1>;
+ };
Doing so you can adapt to your SoC/board setup easily.
If you don't put those lines in devicetree, the ov5640 default init
sequence is used which set the polarity as defined in below comment:
ov5640_set_stream_dvp()
[...]
+ * Control lines polarity can be configured through
+ * devicetree endpoint control lines properties.
+ * If no endpoint control lines properties are set,
+ * polarity will be as below:
+ * - VSYNC: active high
+ * - HREF: active low
+ * - PCLK: active low
+ */
[...]
Best regards,
Hugues.
On 01/10/2018 04:37 PM, Maxime Ripard 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?
>
> Thanks!
> Maxime
> --
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