On 12/16/2018 10:39 PM, Paul Burton wrote: > Hi Marek, Hi, > On Sun, Dec 16, 2018 at 10:08:48PM +0100, Marek Vasut wrote: >>> I did suggest an alternative approach which would rename >>> serial8250_clear_fifos() and split it into 2 variants - one that >>> disables FIFOs & one that does not, then use the latter in >>> __do_stop_tx_rs485(): >>> >>> https://lore.kernel.org/lkml/20181213014805.77u5dzydo23cm6fq@pburton-laptop/ >>> >>> However I have no access to the OMAP3 hardware that Marek's patch was >>> attempting to fix & have heard nothing back with regards to him testing >>> that approach, so here's a simple revert that fixes the Ingenic JZ4780. >>> >>> I've marked for stable back to v4.10 presuming that this is how far the >>> broken patch may be backported, given that this is where commit >>> 2bed8a8e7072 ("Clearing FIFOs in RS485 emulation mode causes subsequent >>> transmits to break") that it tried to fix was introduced. >> >> OK, I tested this on AM335x / OMAP3 and the system is again broken, so >> that's a NAK. > > To be clear - what did you test? This revert or the patch linked to > above? > > This revert would of course reintroduce your RS485 issue because it just > undoes your change. The revert. Which of the two patches do you need me to test. > Either way, commit f6aa5beb45be ("serial: 8250: Fix clearing FIFOs in > RS485 mode again") breaks systems that worked before it so at this late > stage in the 4.20 cycle a revert would make sense to me. If that breaks > RS85 on OMAP3 then my question would be how much can anyone really care > if nobody noticed since v4.10? And why should that lead to you breaking > the JZ4780 which has been discovered before a stable kernel release > includes the breakage? There's always a .y release where this can be properly investigated and solved, instead of breaking one platform or the other. Then again, see the patch from Ezequiel that was just posted, I think it might be a far better solution. -- Best regards, Marek Vasut
