Messages in this thread | | | From | Andy Shevchenko <> | Date | Wed, 13 Jul 2022 14:51:25 +0200 | Subject | Re: [PATCH v2] serial: 8250_dw: Avoid pslverr on reading empty receiver fifo |
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On Wed, Jul 13, 2022 at 2:43 PM Vamshi Gajjela <vamshigajjela@google.com> wrote: > > From: VAMSHI GAJJELA <vamshigajjela@google.com> > > With PSLVERR_RESP_EN parameter set to 1, the device generates an error > response when an attempt to read an empty RBR with FIFO enabled. > > This happens when LCR writes are ignored when UART is busy. > dw8250_check_lcr() in retries to update LCR, invokes dw8250_force_idle() > to clear and reset FIFO and eventually reads UART_RX causing the error. > > Avoid this by not reading RBR/UART_RX when no data is available.
Thanks for an update! My comments below.
...
> + /* > + * With PSLVERR_RESP_EN parameter set to 1, the device generates an > + * error response when an attempt to read empty RBR with FIFO enabled.
an empty
> + */ > + lsr = p->serial_in(p, UART_LSR);
I have just noticed that you do it independently on FIFO enablement.
> + if ((up->fcr & UART_FCR_ENABLE_FIFO) && !(lsr & UART_LSR_DR)) > + return;
I would recommend to move it inside the conditional
if (fcr & FIFO) { lsr = ... if (!(lsr &)) return; }
-- With Best Regards, Andy Shevchenko
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