Re: How to use host1x syncpt?

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Hi Terje,

Forget to add you to this email, could you please help to take a look
at my questions?

Thanks,
-Bryan

On Tue, Feb 4, 2014 at 3:51 PM, Bryan Wu <cooloney@xxxxxxxxx> wrote:
> Hi Stephen and Thierry,
>
> Recently I'm working on upstreaming my V4L2 driver for Tegra video
> input module, which is using host1x syncpt to wait for frame
> capturing.
>
> So here is my basic steps for handling host1x syncpt,
>
> 1. Call host1x_syncpt_request(cam->client.dev, flags); to allocate
> syncpts for my driver.
>
> 2. Program host1x_syncpt_id(sp) into Tegra VI syncpt event register.
> So when VI captures one frame, syncpt will be increased one.
>
> 3. Call thresh = host1x_syncpt_incr_max(sp, 1) to incr max_val of the
> syncpt, which is the threshold for waiting.
>
> 4. Start capture and wait for host1x syncpt event like this
> host1x_syncpt_wait(sp, thresh, WAIT_TIMEOUT, &value);
>
> Is that the right sequence?
>
> host1x_syncpt_incr_max() is not exported and without calling it I
> always got error message like this:
> "tegra-host1x 50000000.host1x: syncpt_load failed: id=1, min=46, max=0, live=46"
> So I have to increase the max_val manually like step 3. And
> host1x_syncpt_incr() won't increase the max_val which will still
> generate this error message.
>
> Actually with the steps I listed, I can capture data from real sensor now.
>
> Thanks,
> -Bryan
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