On Tue, Jul 13, 2021 at 11:54 AM Vignesh Raghavendra <vigneshr@xxxxxx> wrote: > On 7/13/21 1:57 AM, andy@surfacebook.localdomain wrote: > > Tue, Jun 22, 2021 at 11:53:38AM +0530, Vignesh Raghavendra kirjoitti: > >> On 6/22/21 11:45 AM, Jan Kiszka wrote: > >>>>> Vignesh, it seems this quirk needs some soc specific flag added to > >>>>> it maybe? Or maybe UART_OMAP_RX_LVL register is not available for > >>>>> all the SoCs? > >>>>> > >>>> Yes indeed :( > >>>> > >>>>> I think it's best to drop this patch until the issues are resolved, > >>>>> also there are some open comments above that might be answered by > >>>>> limiting this quirk to a specific range of SoCs :) > >>>>> > >>>> Oops, I did test patch AM33xx assuming its equivalent to OMAP3, but UART > >>>> IP is quite different. I will respin the patch making sure, workaround > >>>> applies only to AM65x and K3 SoCs. > >>>> > >>>> Regards > >>>> Vignesh > >>>> > >>> What's the status here for AM65x? The issue remains present on that > >>> platform, and I was hoping to see a quick follow up that limit the fix > >>> to that target. > >> > >> Sorry for the delay, I am trying to find which other TI SoCs are > >> affected by this issue. But that exercise will need a bit more time. > >> Will send a fix to address K3 SoCs like AM65x today/tomo. > > > > This all reminds me the very similar issue one found on Intel integrated > > (Synopsys DesignWare based) UARTs: > > > > Hmm, yes, seems like common problem with some 8250 UARTs although not > all TI SoCs show this behavior even though they all claim 8250 compatible. > > > https://lore.kernel.org/linux-serial/20170206233000.3021-1-dianders@xxxxxxxxxxxx/ > > I am not sure if reading UART_LSR is a good idea in the above patch. > Some flags in LSR register are cleared on read (at least that's the case > for UARTs on TI SoCs) and thus can result in loss of error/FIFO status > information. > > > https://lore.kernel.org/linux-serial/1440015124-28393-1-git-send-email-california.l.sullivan@xxxxxxxxx/ > > > > Looks like this never made it. > > Given the quirks associated with 8250 UARTs, workarounds would need to > be tied to specific variants, so I don't know if its possible to > implement the fix in 8250 core IRQ handler. I believe they are all are derivatives from Synopsys DesignWare one or another version of it. > PS: v2 of $patch is already merged. I noticed after sending that email. -- With Best Regards, Andy Shevchenko
