On Tue, Sep 15, 2009 at 03:32:05PM -0400, Paul Gortmaker wrote: >[Re: RFC: delete UART current-speed from 4xx DTS?] On 15/09/2009 (Tue 11:32) >Josh Boyer wrote: > >> On Tue, Sep 15, 2009 at 10:31:36AM -0400, Paul Gortmaker wrote: >> >One of the guys here was getting a messed up console on a bamboo board > >I meant to say Yosemite board (and hence u-boot), sorry for that. It >gives garbage up until the udbg -> ttyS0 handover, at which point the >console=ttyS0,115200 fixes things.
Ok. >> >(on linux boot), which he traced to the fact that the default dts has a >> >9600 baudrate coded into it (board was running 115k2, not 9600). Either >> >deleting the line, or replacing the 9600 with zero fixed the problem. >> >> Once booted, was there a valid current-speed property in /proc/device-tree >> for the serial node? I'm curious if U-Boot created it, or if the kernel >> just used whatever baud was present already. > >Had to go back to get this info; it turns out there is a valid prop in >all the serial nodes (2.6.31-rc7), and hexdumping it gives 0x2580 (9600). Sorry, that was after you removed the property in the DTS entirely, or setting it to 0, or just using the existing DTS as-is? I should have phrased my question better, but I think I answered it myself already. In my brief test with Sequoia and Bamboo, I removed the current-speed property entirely and once booted there was no property in the serial node, which is what I would expect for the old version of U-Boot on these boards. The good news is that it seems to work fine :). >> When I did the bamboo port a while ago, I recall having issues with either >> a missing clock-frequency or current-speed (or both perhaps) and the >> bootloader >> on the board was the original PIBS. It might have been an issue with PIBS >> but I'm guessing the rest of the 4xx boards copied from either Ebony or >> Bamboo in their ports and hence contain that property. > >Right - so there could still perhaps be the same issue with PIBS/bamboo >present that you saw earlier (given my inability to keep board names >straight) OK. I'll be sure to test PIBS. > >> >> >Looking at the Fsl boards, it seems that 99% of them don't list any >> >current-speed at all. I'm willing to whip up a patch to delete them >> >> I think 99% of them use U-Boot, which should fix things up either way. > >This is the interesting part -- being a yosemite (u-boot), I would have >thought so as well. I've not looked at the u-boot code, but it may only >add a current-speed if there isn't one yet. At least that is what the >behaviour tends to indicate. Board is running u-boot 1.3.3 so what we >are seeing here may not reflect what current u-boot code is doing >anyway... Yeah, 1.3.3 is pretty old. However, I _think_ the kernel will just leave the baud rate alone entirely without a current-speed property and without console=ttyS0,<baud rate>. Example: linux:/proc/device-tree/plb/opb/ser...@ef600300 # ls clock-frequency device_type interrupts reg compatible interrupt-parent name virtual-reg linux:/proc/device-tree/plb/opb/ser...@ef600300 # cat /proc/cmdline rootdelay=15 root=/dev/sda1 rw ip=off linux:/proc/device-tree/plb/opb/ser...@ef600300 # uname -a Linux linux 2.6.31 #4 Tue Sep 15 16:57:49 UTC 2009 ppc ppc ppc GNU/Linux linux:/proc/device-tree/plb/opb/ser...@ef600300 # cat /proc/cpuinfo processor : 0 cpu : 440EP Rev. B clock : 399.999996MHz revision : 24.211 (pvr 4222 18d3) bogomips : 799.99 timebase : 399999996 platform : PowerPC 44x Platform model : amcc,bamboo Memory : 191 MB linux:/proc/device-tree/plb/opb/ser...@ef600300 # >> I can test bamboo with PIBS, ebony, holly (which isn't 4xx even though it's >> a tree name) with PIBS, sequoia, taishan, yosemite, and walnut. Perhaps a >> few >> of the 405 boards I have as well. >> >> It's easy enough for me to whip up a patch, and since I'll be testing either >> way I'd be happy to do that if you'd like. > >Sure -- the testing effort will be greater than the time to make the >patch, so you doing coverage on all those would be great. I think I've >probably only got easy immediate access to a PIBS/bamboo at the moment. >We already know the yosemite is OK with the change, so that is one less >to test. OK, sounds good. I'll do some more testing over the next few days and post a patch. Thanks for bringing this to my attention. josh _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
