Re: [PATCH 0/3] [media] tvp5150: Migrate to media-controller framework and add video format detection

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On Sat, Oct 1, 2011 at 7:46 PM, Enrico <ebutera@xxxxxxxxxxxxxxxx> wrote:
> On Sat, Oct 1, 2011 at 7:27 PM, Javier Martinez Canillas
> <martinez.javier@xxxxxxxxx> wrote:
>> Yes, I saw it. That is why I didn't post our modifications to the ISP
>> CCDC driver. Our approach is very similar to the one followed by TI
>> (changing the CCDC output buffer every two VD0 interrupts) but we did
>> different a few things:
>>
>> - decouple next buffer obtaining from last buffer releasing
>> - maintain two buffers (struct isp_buffer), current and last
>> - move move most of the logic to the VD1 interrupt since the ISP is
>> already busy while execution VD0 handler.
>
> If you think it is a better approach you can submit it for review,
> right now there is no "clean" version supporting bt656 so yours can be
> the one.
>
>

Ok, I don't know if my approach is the "cleaner" version to support
bt656, but I will cleanup the code to be in a merge-able state and
send for review.

Something that I don't know if I got it right is configure the CCDC to
capture and odd numbers of lines (i.e: 625 lines from a PAL frame)
since the first and second sub-frames have different numbers of lines
(i.e: 313 and 312).

My solution was to reprogram the CCDC in the VD1 interrupt handler so
it can use the new configuration for the next sub-frame:

static void ispccdc_change_numlines(struct isp_device *isp, int numlines)
{
	isp_reg_writel(isp, ((numlines - 1) << ISPCCDC_VDINT_0_SHIFT) |
		       ((numlines * 2 / 3) << ISPCCDC_VDINT_1_SHIFT),
		       OMAP3_ISP_IOMEM_CCDC, ISPCCDC_VDINT);
	isp_reg_writel(isp, (numlines - 1)
		       << ISPCCDC_VERT_LINES_NLV_SHIFT,
		       OMAP3_ISP_IOMEM_CCDC, ISPCCDC_VERT_LINES);
}

Is this the right approach? because I didn't find in the TRM how to
configure the CCDC to generate the VD0 and VD1 interrupts with
variable frame vertical length.

>>>>> Even if it does detect the signal shape (NTSC, PAL), doesn't one still need
>>>>> to [externally] configure the pads for this shape?
>>>>>
>>>>
>>>> Yes, that is why I wanted to do the auto-detection for the tvp5151, so
>>>> we only have to manually configure the ISP components (or any other
>>>> hardware video processing pipeline entities, sorry for my
>>>> OMAP-specific comments).
>>>
>>> Laurent was not very happy [3] about changing video formats out of the
>>> driver control, so this should be discussed more.
>>>
>>> [3]: http://www.spinics.net/lists/linux-omap/msg56983.html
>>>
>>>
>>
>> Ok, I thought it was the right thing to do, my bad. Lets do it from
>> user-space then using the MCF.
>
> I see there is some ongoing discussion about a similar topic, so just
> follow it and see how it turns out.
>
> Enrico
>

Ok, I will. Thank you very much for your comments.

Best regards,

-- 
Javier Martínez Canillas
(+34) 682 39 81 69
Barcelona, Spain
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