Werner Almesberger escreveu:
Andy Green wrote:
Maybe the GTA01 batch of LCMs are
themselves different from the ones we currently use.
I connected my GTA01Bv4 LCM to a GTA02v4, and it showed all the same
flicker.
Maybe this is because the GTA01 issued the video at a higher
frame rate and the flicker is less visible.
That is the case, yes. I just measured that HSYNC on GTA02 is 40.9kHz,
while on GTA01 it's 55.4kHz (!)
With GTA01, it does flicker when using cpufreq on some frequencies.
The problem on GTA01 is that the base frequency can be either HCLK/4 or
HCLK/2, and neither gets near the ideal set of values. The kernel will
always try to stay below the specified "pixclock" parameter; but, while
that is set on mach-gta01.c to 40000, the value actually used after the
rouding (on the default core frequency) corresponds to a pixclock of 30075.
To reduce the issue, I changed the parameter on mach-gta01.c to 35000
instead of 40000 on my cpufreq tree (the frequencies which flicker the
most are the ones where the effective value is near 40000). I also made
cpufreq stop using the slower frequencies (ones which would want to use
HCLK instead of HCLK/2, which is not possible) when the LCD controller
is enabled (and, unfortunately, it currently never gets disabled; the
screen only gets blanked). Both changes combined make the effective
pixclock range 17500-35000 instead of 20000-40000. However, that's only
a workaround (the flicker is still there, only reduced, and you can
still notice when "ondemand" is giving you a slower frequency).
--
Cesar Eduardo Barros
[EMAIL PROTECTED]
[EMAIL PROTECTED]
