Hi Maxime, On Thu, 11 Jan 2018 13:40:18 +0100 Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx> wrote: > Hi Yong, > > On Thu, Jan 11, 2018 at 09:15:08AM +0800, Yong wrote: > > > 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? > > Yes, on an H3. Looking at all the Allwinner datasheet I could get my > hands on, they are all documented in the same way. However, I really > start to wonder whether the polarity shouldn't be reversed. > > At least the fact that VSYNC is clearly active low on the > oscilloscope, while I have to set it active high in the controller > seems like a strong hint :) The BSP code of Allwinner also treat V4L2_MBUS_VSYNC_ACTIVE_HIGH as they documented 'positive'. Maybe there need some more tests to confirm if the datasheet and BSP code are both wrong. > > > No. I only tested with a BT1120 signal generated by FPGA or ADV7611. HSYNC > > and VSYNC are not used. > > Ok, that's good to know :) > > > 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. > > I did already, and the only combination that works is the one that is > the inversed polarity on HSYNC and VSYNC than what the sensor setup. > > Maxime > > -- > Maxime Ripard, Free Electrons > Embedded Linux and Kernel engineering > http://free-electrons.com Thanks, Yong
