On Thu, 19 Feb 2009, morimoto.kunin...@renesas.com wrote:
>
> Dear Guennadi
>
> > Hm, ok, maybe I can ask you about one more test, if you don't mind. The
> > thing is, you only see the problem, if after the ->active buffer has been
> > freed in free_buffer(), your DMA engine continues writing to the freed
> > memory, but you only notice this, if some other driver manages to grab and
> > use it in this time, then its data is going to be overwritten.
> (snip)
> > Best would be to first try all three loops without the patch from Magnus
> > and see if any of them triggers. And use a larger frame (maximum that your
> > sensor can deliver) to give the DMA engine more time per frame.
>
> Hmm. maybe I could understand...
>
> OK.
> I tested with MigoR + ov772x + following way.
>
> 1) apply patch to kernel
>
> > diff -u a/drivers/media/video/sh_mobile_ceu_camera.c
> > b/drivers/media/video/sh_mobile_ceu_camera.c
> > --- a/drivers/media/video/sh_mobile_ceu_camera.c
> > +++ b/drivers/media/video/sh_mobile_ceu_camera.c
> > @@ -326,6 +326,7 @@
> > spin_lock_irqsave(&pcdev->lock, flags);
> >
> > vb = pcdev->active;
> > + WARN_ON(vb->state == VIDEOBUF_NEEDS_INIT);
> > list_del_init(&vb->queue);
> >
> > if (!list_empty(&pcdev->capture))
>
> 2) apply patch to capture-example
>
> I think your wanting to say is this...
>
> diff -u capture_example.c capture_example.c.test
> --- capture_example.c 2009-01-24 09:35:12.000000000 +0900
> +++ capture_example.c.test 2009-02-19 18:09:32.000000000 +0900
> @@ -590,6 +590,8 @@
>
> int main(int argc, char **argv)
> {
> + int i;
> +
> dev_name = "/dev/video0";
>
> for (;;) {
> @@ -648,11 +650,14 @@
> }
>
> open_device();
> - init_device();
> - start_capturing();
> - mainloop();
> - stop_capturing();
> - uninit_device();
> + for (i=0 ; i<100 ; i++) {
> + printf("%d ", i);
> + init_device();
> + start_capturing();
> + mainloop();
> + stop_capturing();
> + uninit_device();
> + }
> close_device();
> fprintf(stderr, "\n");
> return 0;
>
> 3) test this capture_example.
>
> Then, It say
>
> ======================================================================
> camera 0-0: SuperH Mobile CEU driver attached to camera 0
> camera_host0: Format 0 not found
> .0 ... camera_host0: Format 0 not found
> ------------[ cut here ]------------
> Badness at 8c141b9e [verbose debug info unavailable]
>
> Pid : 869, Comm: c2
> CPU : 0 Not tainted (2.6.29-rc4-00197-g41480ae-dirty #801)
>
> PC is at sh_mobile_ceu_irq+0x2a/0xc8
> PR is at handle_IRQ_event+0x2e/0x68
> PC : 8c141b9e SP : 8fe15e40 SR : 400001f1 TEA : 2961ba40
> R0 : 8ff05afc R1 : 00000000 R2 : 8fe14000 R3 : 00000000
> R4 : 8ff05a00 R5 : 8ff05a00 R6 : 00000010 R7 : 00000000
> R8 : 8ff416e0 R9 : 000000f0 R10 : 00000000 R11 : 00000034
> R12 : 8ff414d0 R13 : 8ff3a1e0 R14 : 8ff89e74
> MACH: 00000000 MACL: 00000c30 GBR : 29686450 PR : 8c030e0a
>
> Call trace:
> [<8c030e0a>] handle_IRQ_event+0x2e/0x68
> [<8c0326a8>] handle_level_irq+0x6c/0x100
> [<8c00356c>] do_IRQ+0x34/0x5c
> [<8c007118>] ret_from_irq+0x0/0x10
> [<8c003538>] do_IRQ+0x0/0x5c
> [<8c0f2c44>] memset+0x30/0x4c
> [<8c00b25a>] dma_alloc_coherent+0x5e/0x148
> [<8c141742>] __videobuf_mmap_mapper+0xbe/0x1a4
> [<8c13fb88>] videobuf_mmap_mapper+0x3c/0x70
> [<8c050ad8>] mmap_region+0x184/0x34c
> [<8c005234>] old_mmap+0x60/0xa8
> [<8c007266>] syscall_call+0xc/0x10
> [<8c0051d4>] old_mmap+0x0/0xa8
Yesss! There you go - this is the race we are hunting.
> camera 0-0: SuperH Mobile CEU driver detached from camera 0
> Trace/breakpoint trap
> ======================================================================
>
> 4) apply Magnus patch
> 5) and test it again
>
> then It say...
>
> ========================================================
> -bash-3.00# ./c2 -d /dev/video0 -f -c 4
> camera 0-0: SuperH Mobile CEU driver attached to camera 0
> camera_host0: Format 0 not found
> .0 ... camera_host0: Format 0 not found
> .1 ... camera_host0: Format 0 not found
> .2 ... camera_host0: Format 0 not found
> .3 ... camera_host0: Format 0 not found
> (snip)
> .96 ... camera_host0: Format 0 not found
> .97 ... camera_host0: Format 0 not found
> .98 ... camera_host0: Format 0 not found
> .99 ...camera 0-0: SuperH Mobile CEU driver detached from camera 0
> ========================================================
Nice and clean. Good, now I just need a formal patch submission with a
"Tested-by" string, please.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
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