Re: [Linux-fbdev-devel] [PATCH 3/6] pxa: fix pxa168 lcd controller vsync/hsync timing error

[Jun N. <nie...@gm...>]

2009/11/9 Eric Miao <eri...@gm...>:
>>> Could you please help double check this? My understanding is
>>> FB_SYNC_VERT_HIGH_ACT means it's a positive pulse covering all the
>>> valid HSYNCs, and a rising edge of VSYNC means a start of the frame.
>>>
>>> However, CFG_INV_VSYNC is '1' means the opposite.
>>>
>>
>> My understanding is that high active means high level trigger new
>> frame/line. Below page support my point if it is not wrong.
>>
>> http://www.arcadecollecting.com/info/Sync_fixing.txt
>>
>
> Tried to find the specific diagram in the spec on what CFG_INV_* means
> but failed, can you help verified this with an oscilloscope and let know
> the result? This is a fix then, and I'd like it to get into .32, sorry for late
> reply.
>

Hi, Eric
If do not set CFG_INV_VSYNC and CFG_INV_HSYNC bits, controller output
is as below in oscilloscope.

                  ||               ||                ||
.._________||_________||_________||____... HSYNC (active high)

                                                    _____
                                                     |     |
.._____________________________|     |_... VSYNC (active high)

So I should mark HSYNC_HIGH and VSYNC_HIGH in platform code and keep
driver code as  below original code.
       x |= (info->var.sync & FB_SYNC_VERT_HIGH_ACT) ? 0 : 0x00000008;
       x |= (info->var.sync & FB_SYNC_HOR_HIGH_ACT) ? 0 : 0x00000004;

Thanks!

Jun