On Thu, Nov 28, 2019 at 11:51 AM Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > On Thu, Nov 28, 2019 at 11:26:24AM +0800, Chen-Yu Tsai wrote: > > On Thu, Nov 28, 2019 at 11:06 AM Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > > > > > Hi, > > > > > > On Thu, Nov 28, 2019 at 10:26:08AM +0800, Yong wrote: > > > > Hi Ondrej, > > > > > > > > This has been discussed. > > > > And Maxime sent a patch for this: > > > > https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg127149.html > > > > > > Thanks for pointing to the previous patch. But that patch doesn't make any > > > sense, and breaks things for me, and doesn't even match BSP code, which > > > has no such reversal, and works fine with about 30 cam drivers. > > > > > > Also how do you explain my findings? > > > > > > My camera is sending correct signals, verified by looking at them actually (see > > > below), and CSI is not receiving the image. I have to flip HSYNC/VSYNC to be > > > oposite of that what CSI driver expects and I get a noisy image and if I fix > > > PCLK polarity too, the noise goes away, which means now I'm also sampling when > > > the data are stable and not when they're changing. > > > > > > Here: (output from my cam, that I configured to have VSYNC ACTIVE LOW, HSYNC > > > ACTIVE LOW) And the signal is clearly that, as you can see yourself: > > > > > > https://megous.com/dl/tmp/98df81b7ed0126ec.png > > > > From the looks of things you have active-high VSYNC with active-low HREF. > > HREF is not the same as HSYNC, in fact quite the opposite. V/H SYNC are > > pulses, active only when there should be no data and the line/frame switch > > happens, while V/H REF are held active when there is data. I personally > > find these terms very confusing. :( > > > > Now the timing diagrams in the Allwinner manuals would suggest that when > > they are talking about H/V SYNC, they are actually referring to H/V REF. > > The HSYNC line is high/active when there is valid data, and the VSYNC line > > is high/active for the duration of the frame. > > > > I think both sides need to be checked that they are using the correct > > polarity, and maybe also have the media maintainers clarify how the > > polarity should be interpreted when the hardware uses H/V ref instead > > of H/V sync. > > Oh my, so it's just a terminology issue? :) > > This probably should be docummented somewhere. I just thought xSYNC_ACTIVE_HIGH > meant the respective signals are supposed to be HIGH during active phase of data > transmission: that is VSYNC HIGH during entire frame, and HSYNC high during row. Unfortunately I'm having a hard time finding a definitive source for this. My rationale is that since the sync signal is a pulse, the active part would refer to the pulsing part, not the at rest part. > DT bindings documentation doesn't help much either. Yeah. I think this should be sorted out for the whole subsystem, as this not only affects platform drivers, but the sensor drivers as well. > And obviously manufacturers are confused too. > > https://megous.com/dl/tmp/fae07dfb4897bbb3.png It seems at least OmniVision uses VSYNC + HREF. GalaxyCore seems to use VSYNC + HREF as well, but they call it HSYNC, and VSYNC polarity is inverted. :( The OV7670 sensor I was testing had an option to switch from HREF to HSYNC, and another one to invert HREF. Talk about confusing. And HSYNC != inverted HREF. They will be some PCLK cycles apart. > HSYNC/VSYNC "low valid" produces what you see on the previous signal capture > I posted. ;) Thanks. I don't have a scope or logic analyzer. I'll wait for the people who do to figure this out. Regards ChenYu > regards, > o. > > > > > ChenYu > > > > > The above signals are received with CSI driver configured with > > > V4L2_MBUS_VSYNC_ACTIVE_HIGH V4L2_MBUS_HSYNC_ACTIVE_HIGH. So CSI driver is > > > clearly wrong. > > > > > > I think this is pretty clear the driver is buggy. At least for A83T SoC. > > > > > > I'm not sure what Maxime found out, but he should probably re-check his > > > findings. Maxime, can you comment on this? > > > > > > regards, > > > o. > > > > > > > On Thu, 28 Nov 2019 03:02:59 +0100 > > > > Ondrej Jirman <megous@xxxxxxxxxx> wrote: > > > > > > > > > This was discovered by writing a new camera driver and wondering, why > > > > > hsync/vsync polarity setting behaves in reverse to what would be > > > > > expected. Verified by looking at the actual signals and the SoC > > > > > user manual. > > > > > > > > > > Fixes: 5cc7522d8965 ("media: sun6i: Add support for Allwinner CSI V3s") > > > > > Signed-off-by: Ondrej Jirman <megous@xxxxxxxxxx> > > > > > --- > > > > > drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c | 6 +++--- > > > > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > > > > > > > diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c > > > > > index f17e5550602d..98bbcca59a90 100644 > > > > > --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c > > > > > +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c > > > > > @@ -417,12 +417,12 @@ static void sun6i_csi_setup_bus(struct sun6i_csi_dev *sdev) > > > > > if (flags & V4L2_MBUS_FIELD_EVEN_LOW) > > > > > cfg |= CSI_IF_CFG_FIELD_POSITIVE; > > > > > > > > > > - if (flags & V4L2_MBUS_VSYNC_ACTIVE_LOW) > > > > > + if (flags & V4L2_MBUS_VSYNC_ACTIVE_HIGH) > > > > > cfg |= CSI_IF_CFG_VREF_POL_POSITIVE; > > > > > - if (flags & V4L2_MBUS_HSYNC_ACTIVE_LOW) > > > > > + if (flags & V4L2_MBUS_HSYNC_ACTIVE_HIGH) > > > > > cfg |= CSI_IF_CFG_HREF_POL_POSITIVE; > > > > > > > > > > - if (flags & V4L2_MBUS_PCLK_SAMPLE_RISING) > > > > > + if (flags & V4L2_MBUS_PCLK_SAMPLE_FALLING) > > > > > cfg |= CSI_IF_CFG_CLK_POL_FALLING_EDGE; > > > > > break; > > > > > case V4L2_MBUS_BT656: > > > > > -- > > > > > 2.24.0 > > > > > > > > > > -- > > > > > You received this message because you are subscribed to the Google Groups "linux-sunxi" group. > > > > > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@xxxxxxxxxxxxxxxx. > > > > > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20191128020259.1338188-1-megous%40megous.com. > > > > > > > > > > > > Thanks, > > > > Yong > > > > > > -- > > > You received this message because you are subscribed to the Google Groups "linux-sunxi" group. > > > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@xxxxxxxxxxxxxxxx. > > > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20191128030653.5fhcolvib6tzf4zc%40core.my.home. > > -- > You received this message because you are subscribed to the Google Groups "linux-sunxi" group. > To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@xxxxxxxxxxxxxxxx. > To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/20191128035056.77554jav3eo6h7su%40core.my.home.
