From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sergei Shtylyov Subject: Re: [PATCH] serial: fix au1xxx UART0 irq setup Date: Thu, 25 Oct 2007 18:09:47 +0400 Message-ID: <4720A3AB.7070307@ru.mvista.com> References: <4720A11E.5060101@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from gateway-1237.mvista.com ([63.81.120.155]:45385 "EHLO imap.sh.mvista.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1754439AbXJYOJj (ORCPT ); Thu, 25 Oct 2007 10:09:39 -0400 In-Reply-To: <4720A11E.5060101@gmail.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Jan Nikitenko Cc: Ralf Baechle , linux-mips@linux-mips.org, linux-serial@vger.kernel.org Jan Nikitenko wrote: > UART0 on Alchemy mips platforms (au1xxx) does not use real uart's hw > irq, causing 'ttyS0: 1 input overrun(s)' kernel message with data loss, > when more characters than uart's fifo size were to be received by the uart. > This problem can be experienced for example when uart0 is used as a > serial console on au1550 and more than 16 characters are pasted from > clipboard to the console. > > The is_real_interrupt(irq) macro is defined in drivers/serial/8250.c as > a check, if the irq number is other than zero. > Because UART0 on au1xxx platforms uses irq number 0, the > is_real_interrupt() check fails and serial8250_backup_timeout() is used > instead of uart's hw irq. > > The patch redefines the is_real_interrupt(irq) macro, as suggested in > the comment above the macro definition in 8250.c, in the > asm-mips/serial.h to be always true for CONFIG_SERIAL_8250_AU1X00. > This allows the irq number 0 to be used as hw irq for the alchemy uart0 > and fixes the overrun problem. > > Signed-off-by: Jan Nikitenko > > --- > > include/asm-mips/serial.h | 5 +++++ > 1 file changed, 5 insertions(+) > > > ------------------------------------------------------------------------ > > diff --git a/include/asm-mips/serial.h b/include/asm-mips/serial.h > index c07ebd8..526bd2e 100644 > --- a/include/asm-mips/serial.h > +++ b/include/asm-mips/serial.h > @@ -19,4 +19,9 @@ > */ > #define BASE_BAUD (1843200 / 16) > > +#ifdef CONFIG_SERIAL_8250_AU1X00 > +#undef is_real_interrupt > +#define is_real_interrupt(irq) (1) > +#endif > + > #endif /* _ASM_SERIAL_H */ I wonder why such patch hasn't still been checked, despite being suggested several times... WBR, Sergei