Messages in this thread | | | From | Andy Shevchenko <> | Date | Tue, 12 Jul 2022 15:25:57 +0200 | Subject | Re: [PATCH] serial: 8250_dw: Avoid pslverr on reading empty receiver fifo |
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On Tue, Jul 12, 2022 at 3:16 PM Vamshi Gajjela <vamshigajjela@google.com> wrote: > > From: VAMSHI GAJJELA <vamshigajjela@google.com> > > With PSLVERR_RESP_EN parameter set to 1, device generates an error
the device
> response when an attempt to read empty RBR with FIFO enabled.
an empty
> This happens when LCR writes are ignored when UART is busy. > dw8250_check_lcr() in retries to updateLCR, invokes dw8250_force_idle() > to clear and reset fifo and eventually reads UART_RX causing pslverr.
fifo --> FIFO pslverr --> the error
> Avoid this by not reading RBR/UART_RX when no data is available.
...
> + unsigned int lsr; > struct uart_8250_port *up = up_to_u8250p(p);
Can we keep it ordered according to the reversed xmas tree?
...
> + /* > + * With PSLVERR_RESP_EN parameter set to 1, device generates pslverr
the device pslverr --> an
> + * error response when an attempt to read empty RBR with FIFO enabled
Missed period.
> + */ > + lsr = p->serial_in(p, UART_LSR);
The only caller of this function already has the lsr value, why you can't (re)use it?
> + if ((up->fcr & UART_FCR_ENABLE_FIFO) && !(lsr & UART_LSR_DR)) > + return;
-- With Best Regards, Andy Shevchenko
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