Re: [Mjpeg-developer] [PATCH] zoran: more fixes

[Jean D. <kh...@li...>]

Hi Trent,

On Tue, 5 Jun 2007 21:20:22 -0700 (PDT), Trent Piepho wrote:
> On Sat, 2 Jun 2007, Ronald Bultje wrote:
> > On 6/2/07, Trent Piepho <xy...@sp...> wrote:
> > > After capture stops, the FrabGrab flag is stuck at 1 (capture pending).
> > > Writing a zero to it doesn't reset it, I tried that.  So this warning will
> > > print every time capture stops/starts.
> >
> > Is that a hardware bug then? Please add a comment that FrameGrab used to be
> > there and that it's always 1, then I'm OK with it
> 
> Ok, I'll add some sort of comment.
> 
> From the datasheet, it seems like the expected operation.  The FrameGrab
> bit is listed as "RS" not "RW", so I take that to mean one should only
> expect to be able to Read and Set the bit, but not clear it to zero.
> 
> When FrameGrab is set to 1, it triggers the zr36067 to start a capture, and
> the zr36067 chip will clear FrameGrab to zero when the capture is done.  If
> you turn off a pending capture before it finishes, no capture is completed
> to trigger clearing FrameGrab, so it just stays at one.
> 
> The bug in the driver that this patch fixes (besides the extra warning), is
> that one must _write_ a one to FrameGrab to trigger a capture, even if
> FrameGrab is already one because of the previous pending capture that was
> aborted.  If you don't write a one after turning back back on, the chip
> won't acutally start capturing frames.

Wouldn't it be cleaner to let the capture finish so that the hardware
sets FrameGrab to 0?

I don't know much about the whole thing so feel free to disregard this
comment if it doesn't make sense to you.

I will try to find some time to test your patch later this week. Wanted
to do it before but couldn't find the time, sorry.

-- 
Jean Delvare