On Tue, Jan 19, 2016 at 10:35 PM, Simon Glass <s...@chromium.org> wrote: > Hi, > > On 18 January 2016 at 23:46, Craig McQueen <craig.mcqu...@innerrange.com> > wrote: >>> Tom Rini wrote: >>> >>> On Mon, Jan 11, 2016 at 09:59:18AM -0700, Simon Glass wrote: >>> > Hi Craig, >>> > >>> > On 20 December 2015 at 19:07, Craig McQueen >>> > <craig.mcqu...@innerrange.com> wrote: >>> > > This is to avoid the boot sequence halting due to initial "junk" >>> > > received on serial input. >>> > > >>> > > Signed-off-by: Craig McQueen <craig.mcqu...@innerrange.com> >>> > > --- >>> > > I have found that on the BeagleBone Black, U-Boot occasionally halts >>> > > at the U-Boot prompt at boot-up, whether power-up, warm external >>> > > reset or software reset. I have seen other people report the same issue. >>> > > >>> > > This seems to be due to U-Boot receiving "junk" data on the serial >>> > > console. The BeagleBone Black has a pull-down resistor which was >>> > > apparently added to try to mitigate this issue, but it doesn't >>> > > entirely fix it. >>> > >>> > I wonder if this can be fixed for that board only? >>> >>> No, and it's not -exactly- a that board only problem. It's a HW design >>> issue >>> that can show up elsewhere too. I _think_ however in this case the answer >>> would be to migrate to perhaps CONFIG_AUTOBOOT_KEYED_CTRLC as that's >>> one of the reason various other boards use that set of options. >>> >>> I would suggest bringing this up on the beaglebone list to see what the >>> various people that ship and support these boards think, thanks! >> >> Other options such as CONFIG_AUTOBOOT_KEYED_CTRLC sound like a work-around >> of the problem, rather than a fix of the root-cause. But maybe that's just >> my opinion. Simon Glass' suggestion (clear out the UART input buffer when >> the driver is probed) sounded reasonable, but I haven't tried it. > > Since it seems like a hardware bug, we can only have a workaround. A > real fix would involve fixing the root cause, i.e. fixing the > hardware. > >> >> I think BeagleBone Black definitely needs _some_ sort of fix -- currently >> BBB can randomly fail to boot, which isn't good. If my patch isn't wanted, >> then please implement a suitable alternative. > > How about what Tom suggested? Ctrl-C is not likely to happen by accident.
This should be good enough for everyone, it'll look for an exact match over serial "<space>" otherwise it'll ignore everything else: http://lists.denx.de/pipermail/u-boot/2016-January/241286.html Regards, -- Robert Nelson https://rcn-ee.com/ _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot