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
