linux-kernel - Re: [PATCH v1 0/6] Add support of OV9655 camera

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Message-Id: <E6130F6E-B0D7-48B3-A5FC-D8D7119E31E6@goldelico.com>
Date:   Mon, 3 Jul 2017 14:23:39 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Hugues FRUCHET <hugues.fruchet@...com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Pavel Machek <pavel@....cz>,
        Discussions about the Letux Kernel 
        <letux-kernel@...nphoenux.org>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1 0/6] Add support of OV9655 camera

Hi Hugues,

> Am 03.07.2017 um 14:03 schrieb Hugues FRUCHET <hugues.fruchet@...com>:
> 
> Hi Nikolaus,
> 
> nothing really strange in trace, I wanted to check the latest S_FMT and 
> it is well 1280x1024 YUV:
>>> [  425.579498] video2: VIDIOC_S_FMT: type=vid-cap, width=1280, 
> height=1024, pixelformat=UYVY, field=none, bytesperline=2560, 
> sizeimage=2621440, colorspace=0, flags=0x0, ycbcr_enc=0, quantization=0, 
> xfer_func=0
> 

Thanks for cross-checking.

> You're right that it seems that the ISP is not seeing any data in input.
> Have you double checked the polarities of sync signals ? I see 
> differences in devicetree:
>  960                         ov9655: endpoint {
>  961                                 remote-endpoint = <&parallel_ep>;
>  962 #if 0   // not used by camera driver - define &parellel_ep for isp
>  963                                 bus-width = <8>;
>  964                                 data-shift = <2>;       /* Lines 
> 9:2 are used */
>  965                                 hsync-active = <1>;     /* Active 
> high */
>  966                                 vsync-active = <1>;     /* Active 
> high */
>  967                                 data-active = <1>;      /* Active 
> high */
>  968                                 pclk-sample = <1>;      /* Rising */
>  969 #endif
> 
> Which has been commented out in flavour of:
> 
> 1011 /* parallel camera interface */
> 1012 &parallel_ep {
> 1013         remote-endpoint = <&ov9655>;
> 1014         ti,isp-clock-divisor = <1>;
> 1015         ti,strobe-mode;
> 1016         bus-width = <8>;/* Used data lines */
> 1017         data-shift = <2>; /* Lines 9:2 are used */
> 1018         hsync-active = <0>; /* Active low */
> 1019         vsync-active = <1>; /* Active high */
> 1020         data-active = <1>;/* Active high */
> 1021         pclk-sample = <1>;/* Rising */
> 1022 };
> 
> there is a difference regarding active level of hsync.

Yes, this is from experimenting with our driver patch series to
do the setup in the camera driver. Both chips can configure polarities
but we now have only system defaults in the camera driver. Therefore,
it is commented out for the camera DT node.

The problem is that we never had all this working in DT mode so
our setup here might indeed be buggy.

On the other hand the polarity (HSYNC act. low and VSYNC act. high)
does match the signals seen by oscilloscope.

I will try asap if this makes a difference. There are only 4 combinations...

My expectation is that wrong polarity would only move the
active trigger point around so that I would expect an image
shifted left/right or up/down.

But I don't know enough details of the isp. If it is triggering
sync not by edge but by state and stopping capture for the wrong
state of the sync signal it might not receive enough lines or pixels
as it was initialized for and therefore it may simply wait for
more data instead of reporting "done with 1280x1024 pixels".

> 
> Nevertheless seems OK if I check OMAP3 ISP register:
> CCDC SYN_MODE=0x00071704
> #define ISPCCDC_SYN_MODE_VDPOL			(1 << 2)
> #define ISPCCDC_SYN_MODE_HDPOL			(1 << 3)
> 
> seems well that vertical is 1 and horizontal is 0.
> 

BR and thanks,
Nikolaus