On Friday 17 April 2015 10:52 PM, Geoff Levand wrote:
On Thu, 2015-04-16 at 22:17 +0530, Pratyush Anand wrote:
> Previous transmission must be completed before next character to be
> transmitted, otherwise TX buffer may saturate and we will not see all
> the characters on screen.
>
> @@ -34,6 +38,8 @@ static const char arm64_opts_usage[] __attribute__ ((unused)) =
> " --lite Fast reboot, no memory integrity checks.\n"
> " --page-offset Kernel page-offset for binary image load.\n"
> " --port=ADDRESS Purgatory output to port ADDRESS.\n"
> +" --port-lsr=ADDRESS Purgatory output port line status ADDRESS.\n"
> +" --port-lsr-val=VALUE Purgatory output port Line status expected SET
value when TX empty.\n"
> " --ramdisk=FILE Use FILE as the kernel initial ramdisk.\n"
> " --reuse-cmdline Use command line arg of primary kernel.\n";
We just need to put some chars to the screen, so I want to avoid a lot
of parameters.
I was not able to get even two lines print without it :(
Usually the status register is at a fixed offset from the TX port.
Is
that not the case for the ARM uarts?
Can't we just poll port-lsr until empty then start writing again? That
will at least eliminate port-lsr-val.
infact my first version was using a direct offset with port. Both are
fixed in most of the cases as offset 0x14 and value 0x60.
OK, I will remove the param for now. if someone finds any different
values then later on we can add it.
~Pratyush