Re: Lockup on second streamon with omap3-isp

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Hi Jean-Philippe,

I have had exactly the same problem and the following workaround has caused no regression on our board yet. I can't explain exactly why it works and I think that it is internal to the isp.

In function ccdc_set_stream, don't disable the ccdc_subclk when stopping capture:

                ret = ccdc_disable(ccdc);
                if (ccdc->output & CCDC_OUTPUT_MEMORY)
omap3isp_sbl_disable(isp, OMAP3_ISP_SBL_CCDC_WRITE);
-               omap3isp_subclk_disable(isp, OMAP3_ISP_SUBCLK_CCDC);
+               //omap3isp_subclk_disable(isp, OMAP3_ISP_SUBCLK_CCDC);

I know that it is still a workaround but I hope that maybe it will help someone to understand the real cause of this issue.

Best Regards,
Julien BERAUD

Le 13/12/2012 15:14, jean-philippe francois a écrit :
Hi,

I have news on the "IRQ storm on second streamon" problem.
Reminder :
Given a perfectly fine HSYNC / VSYNC / PIXELCLOK configuration, the
omap3-isp (at least until 3.4) will go into an interrupt storm when
streamon is called for the second time, unless you are able to stop
the sensor when not streaming. I have reproduced this on three
different board, with three different sensor.

On board 1, the problem disappeared by itself (in fact not by itself,
see below) and the board is not in my possession anymore.
On board 2, I implemented a working s_stream operation in the subdev
driver, so the problem was solved because the sensor would effectively
stop streaming when told to, keeping the ISP + CCDC happy
On board 3, I can't stop the streaming, or I did not figure out how to
make it stop  yet.

I tried to disable the HS_VS_IRQ, but it did not help, so I came back
looking at the code of board 1, which was running fine with a 3.4
kernel. And I discovered the problem doesn't happen if I break the
pipeline between two consecutive streamon.

In other word if I do the following :

media-ctl -l '16:0->5:0[1], 5:1->6:0[1]'
media-ctl -f '16:0 [SBGGR8 2560x800 (0, 0)/2560x800]'
yavta ....
yavta ...       <--------- board locks up, soft lockup is fired

But if I do this instead :

media-ctl -l '16:0->5:0[0], 5:1->6:0[0]'
media-ctl -l '16:0->5:0[1], 5:1->6:0[1]'
media-ctl -f '16:0 [SBGGR8 2560x800 (0, 0)/2560x800]'
yavta ....
media-ctl -l '16:0->5:0[0], 5:1->6:0[0]'
media-ctl -l '16:0->5:0[1], 5:1->6:0[1]'
media-ctl -f '16:0 [SBGGR8 2560x800 (0, 0)/2560x800]'
yavta ...       <--------- image are acquired, board doesn't lock up anymore

It would be interesting to go from this workaround to the elimination of
the root cause. What can I do / test next to stop this bug from hapenning ?

Regards,
Jean-Philippe François
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