From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Sakari Ailus <sakari.ailus@iki.fi>
Cc: Pavel Machek <pavel@ucw.cz>, ivo.g.dimitrov.75@gmail.com,
        sre@kernel.org, pali.rohar@gmail.com, linux-media@vger.kernel.org,
        galak@codeaurora.org, mchehab@osg.samsung.com,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] media: Driver for Toshiba et8ek8 5MP sensor
Date: Wed, 02 Nov 2016 02:45:14 +0200
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Hello,

On Tuesday 01 Nov 2016 00:58:45 Sakari Ailus wrote:
> On Sun, Oct 23, 2016 at 10:40:01PM +0200, Pavel Machek wrote:
> > Hi!
> > 
> > > Thanks, this answered half of my questions already. ;-)
> > > 
> > > Do all the modes work for you currently btw.?
> > 
> > Aha, went through my notes. This is what it does in 5MP mode, even on
> > v4.9:
> > 
> > pavel@n900:/my/fcam-dev$ ./camera.py
> > ['-r']
> > ['-l', '"et8ek8 3-003e":0 -> "video-bus-switch":1 [1]']
> > ['-l', '"video-bus-switch":0 -> "OMAP3 ISP CCP2":0 [1]']
> > ['-l', '"OMAP3 ISP CCP2":1 -> "OMAP3 ISP CCDC":0 [1]']
> > ['-l', '"OMAP3 ISP CCDC":1 -> "OMAP3 ISP CCDC output":0 [1]']
> > ['-V', '"et8ek8 3-003e":0 [SGRBG10 2592x1968]']
> > ['-V', '"OMAP3 ISP CCP2":0 [SGRBG10 2592x1968]']
> > ['-V', '"OMAP3 ISP CCP2":1 [SGRBG10 2592x1968]']
> > ['-V', '"OMAP3 ISP CCDC":1 [SGRBG10 2592x1968]']
> > ['-V', '"OMAP3 ISP CCDC":2 [SGRBG10 2592x1968]']
> > Device /dev/video2 opened.
> > Device `OMAP3 ISP CCDC output' on `media' is a video capture (without
> > mplanes) device.
> > Video format set: SGRBG10 (30314142) 2592x1968 (stride 5184) field
> > none buffer size 10202112
> > Video format: SGRBG10 (30314142) 2592x1968 (stride 5184) field none
> > buffer size 10202112
> > 4 buffers requested.
> > length: 10202112 offset: 0 timestamp type/source: mono/EoF
> > Buffer 0/0 mapped at address 0xb63a0000.
> > length: 10202112 offset: 10203136 timestamp type/source: mono/EoF
> > Buffer 1/0 mapped at address 0xb59e5000.
> > length: 10202112 offset: 20406272 timestamp type/source: mono/EoF
> > Buffer 2/0 mapped at address 0xb502a000.
> > length: 10202112 offset: 30609408 timestamp type/source: mono/EoF
> > Buffer 3/0 mapped at address 0xb466f000.
> > 0 (0) [E] any 0 10202112 B 0.000000 2792.366987 0.001 fps ts mono/EoF
> > Unable to queue buffer: Input/output error (5).
> > Unable to requeue buffer: Input/output error (5).
> > Unable to release buffers: Device or resource busy (16).
> > pavel@n900:/my/fcam-dev$
> > 
> > (gitlab.com fcam-dev branch good)
> > 
> > Kernel will say
> > 
> > [ 2689.598358] stream on success
> > [ 2702.426635] Streamon
> > [ 2702.426727] check_format checking px 808534338 808534338, h 984
> > 984, w 1296 1296, bpline 2592 2592, size 2550528 2550528 field 1 1
> > [ 2702.426818] configuring for 1296(2592)x984
> > [ 2702.434722] stream on success
> > [ 2792.276184] Streamon
> > [ 2792.276306] check_format checking px 808534338 808534338, h 1968
> > 1968, w 2592 2592, bpline 5184 5184, size 10202112 10202112 field 1 1
> > [ 2792.276367] configuring for 2592(5184)x1968
> > [ 2792.284240] stream on success
> > [ 2792.368164] omap3isp 480bc000.isp: CCDC won't become idle!
> 
> This is Bad(tm).
> 
> It means that the driver waited for the CCDC to become idle to reprogram it,
> but it didn't happen. This could be a problem in the number of lines
> configured, or some polarity settings between the CCP2 receiver and the
> CCDC.

Is that polarity even configurable ?

> I suspect the latter, but I could be totally wrong here as well since
> it was more than five years I worked on these things. :-I

The OMAP3 ISP CCDC is very fragile when the input signals don't match exactly 
what it expects. This is partly caused by the driver implementation, I believe 
we could do better, but it's been a long time since I looked at that code.

One possible debugging option is to check how much data the CCDC has written 
to memory (if any). If I remember correctly the SBL_CCDC_WR_* registers can 
help there, the target address they store should be incremented as data is 
written to memory.

> > [ 2793.901550] omap3isp 480bc000.isp: Unable to stop OMAP3 ISP CCDC
> 
> And this is probably directly caused by the same problem. :-(

-- 
Regards,

Laurent Pinchart