From mboxrd@z Thu Jan 1 00:00:00 1970 From: sonic zhang Subject: [PATCH v2][bfin-sport-uart] Walk around RX underflow hardware issue in 32-bit SPORT RX reading Date: Mon, 21 Sep 2009 12:11:58 +0800 Message-ID: <1253506318.22138.13.camel@eight.analog.com> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from nwd2mail11.analog.com ([137.71.25.57]:36451 "EHLO nwd2mail11.analog.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750943AbZIUELO (ORCPT ); Mon, 21 Sep 2009 00:11:14 -0400 Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Alan Cox , Linux Kernel , Linux Serial If another interrupt fires while doing a 32-bit read from RX FIFO, a fake RX underflow error will be generated. So disable interrupts to prevent interruption while reading the FIFO. Signed-off-by: Sonic Zhang --- drivers/serial/bfin_sport_uart.h | 16 +++++++++++++++- 1 files changed, 15 insertions(+), 1 deletions(-) diff --git a/drivers/serial/bfin_sport_uart.h b/drivers/serial/bfin_sport_uart.h index 671d41c..f4e5a83 100644 --- a/drivers/serial/bfin_sport_uart.h +++ b/drivers/serial/bfin_sport_uart.h @@ -43,7 +43,21 @@ #define SPORT_GET_TFSDIV(sport) bfin_read16(((sport)->port.membase + OFFSET_TFSDIV)) #define SPORT_GET_TX(sport) bfin_read16(((sport)->port.membase + OFFSET_TX)) #define SPORT_GET_RX(sport) bfin_read16(((sport)->port.membase + OFFSET_RX)) -#define SPORT_GET_RX32(sport) bfin_read32(((sport)->port.membase + OFFSET_RX)) +/* + * If another interrupt fires while doing a 32-bit read from RX FIFO, + * a fake RX underflow error will be generated. So disable interrupts + * to prevent interruption while reading the FIFO. + * Once hardware design can root cause and officially log this, we can + * update the code to use a standard ANOMALY_XXX define. + */ +#define SPORT_GET_RX32(sport) \ +({ \ + unsigned int __ret; \ + local_irq_disable(); \ + __ret = bfin_read32(((sport)->port.membase + OFFSET_RX)); \ + local_irq_enable(); \ + __ret; \ +}) #define SPORT_GET_RCR1(sport) bfin_read16(((sport)->port.membase + OFFSET_RCR1)) #define SPORT_GET_RCR2(sport) bfin_read16(((sport)->port.membase + OFFSET_RCR2)) #define SPORT_GET_RCLKDIV(sport) bfin_read16(((sport)->port.membase + OFFSET_RCLKDIV)) -- 1.6.0