On 1/8/19 1:06 PM, Simon Goldschmidt wrote: > On Tue, Jan 8, 2019 at 12:20 PM Marek Vasut <ma...@denx.de> wrote: >> >> On 1/8/19 7:41 AM, Simon Goldschmidt wrote: >>> On Mon, Jan 7, 2019 at 11:58 PM Marek Vasut <ma...@denx.de> wrote: >>>> >>>> On 1/7/19 10:01 PM, Simon Goldschmidt wrote: >>>>> Am 07.01.2019 um 21:47 schrieb Marek Vasut: >>>>>> On 1/7/19 9:33 PM, Simon Goldschmidt wrote: >>>>>>> Am 07.01.2019 um 21:25 schrieb Marek Vasut: >>>>>>>> On 1/7/19 9:24 PM, Simon Goldschmidt wrote: >>>>>>>>> Am 07.01.2019 um 21:19 schrieb Marek Vasut: >>>>>>>>>> On 1/7/19 8:36 PM, Simon Goldschmidt wrote: >>>>>>>>>>> When debug UART is enabled on socfpga_gen5, the debug uart driver >>>>>>>>>>> hangs >>>>>>>>>>> in an endless loop because 'socfpga_bridges_reset' calls printf >>>>>>>>>>> before >>>>>>>>>>> the debug UART is initialized. >>>>>>>>>>> >>>>>>>>>>> After the generic fix for this in the UART driver did not work >>>>>>>>>>> due to >>>>>>>>>>> portability issues, let's just drop this printf statement when >>>>>>>>>>> called >>>>>>>>>>> from SPL with debug UART enabled. >>>>>>>>>>> >>>>>>>>>>> Signed-off-by: Simon Goldschmidt <simon.k.r.goldschm...@gmail.com> >>>>>>>>>> >>>>>>>>>> Can we have an un-portable fix which at least works on SoCFPGA ? :) >>>>>>>>> >>>>>>>>> This one worked on socfpga but broke rockchip: >>>>>>>>> >>>>>>>>> https://patchwork.ozlabs.org/patch/992553/ >>>>>>>>> >>>>>>>>> However, the message below wasn't shown either with that patch >>>>>>>>> applied. >>>>>>>>> The code just runs too early to enable the UART. >>>>>>>>> >>>>>>>>> Do you want to keep the message (although I failed to see in which >>>>>>>>> situation it can be printed) or do you just dislike the #ifdef thing? >>>>>>>> >>>>>>>> I'd like to keep the error message if possible. Is it possible ? >>>>>>> >>>>>>> I have *never* seen this message yet. I have failed to produce a >>>>>>> situation where it is shown. >>>>>> >>>>>> I believe that. >>>>>> >>>>>>> This function ('socfpga_bridges_reset') is called 5 times throughout the >>>>>>> code, but only *one* single time with 'reset=0' as argument (only with >>>>>>> 0, the code in question is executed). And this is in SPL before >>>>>>> initializing the console and even before the debug UART can be >>>>>>> initialized. >>>>>>> >>>>>>> As I could see, the printf *is* executed on every boot (I saw the code >>>>>>> hanging when enabling debug UART). However, when not booting from FPGA, >>>>>>> it is just normal that the FPGA is not ready when running SPL. Why do >>>>>>> you want an error message here anyway? >>>>>> >>>>>> I was under the impression this is an error message, but it might not be >>>>>> so ? Maybe the wording is incorrect ? >>>>> >>>>> Now that I re-read it, "aborting" is incorrect, yes. >>>>> >>>>> So how should we proceed? This is an error message that can never be >>>>> shown (like the code is now) but breaks debug UART. >>>>> >>>>> I'd say we can drop it altogether. It might only be interesint if (in >>>>> the future) that code would get called from somewhere else (i.e. later, >>>>> after console initialization). >>>>> >>>>> Re-reading spl_gen5.c, there are some 'debug' calls before the debug >>>>> uart is initialized which probably would need to be removed as well, but >>>>> that's a different story... >>>> >>>> How come those don't hang the system then ? >>> >>> I just haven't enabled debug output in spl_gen5.c, yet. I guess they would >>> hang >>> the system when enabling them. >>> >>> While it would be easy to remove these debug statements, to be future-proof >>> it would of course make sense to make the debug UART robust against this. >>> >>> But given the problems with Rockchip ns16550, we would need a dedicated >>> debug UART for socfpga to solve this. And that would probably mean code >>> duplication. >> >> What is the problem with Rockchip ? I don't want various SoCs blocking >> others. > > I had sent a patch that does not wait for the TX fifo to hold more bytes if > the > baudrate prescaler is 0 (according to both the socfgpa and the rockchip docs, > the UART is disabled if the prescaler is 0). > > However, it seems that the prescaler was read back as 0 on a rockchip board > which caused chars to be missing from the console output. > > See this mail: > https://lists.denx.de/pipermail/u-boot/2018-December/350355.html > > I checked with Henri and did not find a solution so I reverted the patch: > https://patchwork.ozlabs.org/patch/1007211/ > > Keeping this patch but only for selected platforms would be my favourite, but > it > would at least mean we need yet another debug UART selection, plus some > changes > to make the "prescaler == 0" detection specific to this new debug UART. > Would this be better acceptable?
Doesn't the DT compatible tell you the UART type ? It does, so you can match on that and apply the workaround accordingly . Or you can cache the prescaler. -- Best regards, Marek Vasut _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
