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The UART core also performs >>>> unconditional reads on the empty FIFO during startup and shutdown >>>> of the port. On the IP version used in TDA54, that interrupt storm >>>> no longer occurs, but reading an empty FIFO instead triggers a data >>>> abort. >>>> >>>> Add a new capability to guard against the empty FIFO reads, avoiding >>>> the data aborts. >>>> >>>> Signed-off-by: Moteen Shah >>>> --- >>>> drivers/tty/serial/8250/8250.h | 1 + >>>> drivers/tty/serial/8250/8250_dw.c | 16 +++++++++++++++- >>>> drivers/tty/serial/8250/8250_port.c | 12 +++++++++--- >>>> 3 files changed, 25 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h >>>> index 77fe0588fd6b..45e13c3a8c14 100644 >>>> --- a/drivers/tty/serial/8250/8250.h >>>> +++ b/drivers/tty/serial/8250/8250.h >>>> @@ -86,6 +86,7 @@ struct serial8250_config { >>>> * STOP PARITY EPAR SPAR WLEN5 WLEN6 >>>> */ >>>> #define UART_CAP_NOTEMT BIT(18) /* UART without interrupt on TEMT available */ >>>> +#define UART_CAP_RXFIFO_EMPTY_READ BIT(19) /* UART needs LSR_DR check before RX read (TDA54) */ >>> >>> IMO, this define naming contradicts with the comment because you >>> effectively say "capable of reading Rx while receive buffer is empty", not >>> that it needs DR check before issuing that read on buffer (~ named exactly >>> opposite of the actual meaning it is being used in the code). >>> >> >> I echo your comments; the naming should reflect that the IP does not >> allow reading an empty FIFO. > > I now recalled we've also the pending RBR -> SRBR change: > > https://lore.kernel.org/linux-serial/20260908141524.20302-1-yang.yicong@picoheart.com/#t > > I wonder if a similar thing would help in this case as well? > Thanks for this patch, we are using similar IP but not same. Let's consume above patch and revert. Thanks > I understand this patch covers more ground than the SRBR patch but can the > IP used in this case read SRBR without aborting? > >> At the same time, I am thinking, reading the FIFO based on the >> UART_LSR_DR bit being set in the serial8250_clear_interrupts and >> serial8250_do_shutdown functions. >> Do you see any side effects to this? > > >