On Thu, Apr 05, 2018 at 07:13:19AM -0300, Jared McNeill wrote: > On Thu, 5 Apr 2018, Manuel Bouyer wrote: > > > But still, being able to switch the console from the bootargs is convenient. > > On the device I'm working with, the normal stdout-path would be the > > graphic display, but when doing developement I switch to serial console. > > It's much easier to switch using bootargs (which I can always do using the > > serial console) than updating the device tree (especially as I can't easily > > extract the sd card, I have to dissasemble the boards for that). > > Totally agree, that's why the console=fb vs stdout-path logic is there in > the first place. > > > I think there's a simple way to get it working: leave stdout-path to the > > serial port, and move sunxi_com to pass 4, so that it's probed before > > sunxi_dep. This way the kernel starts with console on serial, and switches > > to graphic if the command line says so when the graphic drivers are > > activated. > > This would be a regression to the current simplefb setup, which gives early > kernel output to the selected console device. I'd prefer to use FDT_CONSOLE > here rather than relying on device attach ordering kludges.
Does it really do that ? Reading the sources nothing is displayed until simplefb_attach() is called. simplefb_console_consinit() calls genfb_cnattach() but it does nothing. The dmesg buffer is replayed when genfb attaches with the console flag. Actually FDT_CONSOLE doens't prevent the serial port from taking over the console if the stdout-path says so - and even if the command line says otherwise. Actually it works with simplefb because /chosen/framebuffer is probed and attaches after com0 (and it's not an ordering kludge: it's just luck). As sunxidep is attached before com0, com0 has the last word. Unless, of course, if you change stdout-path in the device tree early, My patch to sunxi_platform_bootstrap() just does that for other framebuffer drivers that the simple framebuffer. -- Manuel Bouyer <bou...@antioche.eu.org> NetBSD: 26 ans d'experience feront toujours la difference --