Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751849AbZIUELR (ORCPT ); Mon, 21 Sep 2009 00:11:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751281AbZIUELP (ORCPT ); Mon, 21 Sep 2009 00:11:15 -0400 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 X-IronPort-AV: E=Sophos;i="4.44,422,1249272000"; d="scan'208";a="6608320" Subject: [PATCH v2][bfin-sport-uart] Walk around RX underflow hardware issue in 32-bit SPORT RX reading From: sonic zhang To: Alan Cox , Linux Kernel , Linux Serial Content-Type: text/plain Date: Mon, 21 Sep 2009 12:11:58 +0800 Message-ID: <1253506318.22138.13.camel@eight.analog.com> MIME-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1991 Lines: 47 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/