> 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. 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. It could be worth checking the UART's error flags (break, framing error, parity error, etc), and ignoring a byte with any error. But it looks as though the U-Boot code would need more extensive changes to support that. On what BeagleBone list do you suggest this should be brought up? -- Craig McQueen _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot