On Monday 29 December 2014 12:24:56 Eddie Huang wrote: > Hi Rob, > > On Fri, 2014-12-26 at 15:24 -0600, Rob Herring wrote: > > On Thu, Dec 18, 2014 at 2:33 AM, Eddie Huang <eddie.huang@xxxxxxxxxxxx> wrote: > > > Mediatek UART has highspeed register, but 8250_early.c doesn't > > > support this, so add earlycon in 8250_mtk.c > > > > I don't see any highspeed register setup here. More generically, > > aren't you just skipping any UART setup? That may be useful on other > > platforms with 8250s, too. With the kernel command line version, you > > could perhaps add a "noinit" flag. The DT case is harder, and I'm not > > sure how we should handle that. We could perhaps add a > > "stdout-path-initialized" flag to chosen. > > > > Yes, I skipped UART setup same as msm_serial.c and amba-pl011.c > (although they are standalone serial driver). Just like earlyprintk, I > think earlycon should reuse UART setting in loader. Since some other > platforms with 8250 already depend on this, it's ok to add flags to > distinguish whether 8250 earlycon driver should init hw or not. As you > said, add "noinit" flag is simple, but "stdout-path-initialized" need > more discussion. It would definitely be nice to have consistent behavior, and I also think it would be good to default to noinit for the console, because that is the more likely case. Basically anything that can do debug_ll on ARM already depends on this behavior because the debug_ll infrastructure does not initialize the console before using it. I believe the same is true for powerpc udbg. Arnd -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
