Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754030AbYKRH47 (ORCPT ); Tue, 18 Nov 2008 02:56:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752710AbYKRHvd (ORCPT ); Tue, 18 Nov 2008 02:51:33 -0500 Received: from nwd2mail11.analog.com ([137.71.25.57]:43724 "EHLO nwd2mail11.analog.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751960AbYKRHv1 (ORCPT ); Tue, 18 Nov 2008 02:51:27 -0500 X-IronPort-AV: E=Sophos;i="4.33,624,1220241600"; d="scan'208";a="62690405" From: Bryan Wu To: dbrownell@users.sourceforge.net, spi-devel-general@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org, Yi Li , Bryan Wu Subject: [PATCH 15/16] Blackfin SPI Driver: fix bug - spi controller driver does not assert/deassert CS correctly Date: Tue, 18 Nov 2008 15:52:39 +0800 Message-Id: <1226994760-4301-16-git-send-email-cooloney@kernel.org> X-Mailer: git-send-email 1.5.6.3 In-Reply-To: <1226994760-4301-1-git-send-email-cooloney@kernel.org> References: <1226994760-4301-1-git-send-email-cooloney@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2260 Lines: 61 From: Yi Li This bug can be observed when two SPI devices are sharing the spi bus: One device is set as SPI CS 7, another one is using SPI CS 4. In spi_bfin5xx.c: cs_active(), cs_deactive() are used to control SPI_FLG register. From the debug bellow: cs_active: flag: 0x7f91, chip->flag: 0x7f80, cs: 7 cs_active: flag: 0xef91, chip->flag: 0xef10, cs: 4 When device A (cs_7) activate CS 7, SPI_FLG is set as 0x7f91 (however, SPI_FLG should be set as 0x7f80, or 0x6f91 if in broadcast mode). Due to some HW bug (very possibly), if SPI_FLG is set as 0x7f91, SPISSEL7 is asserted, however SPISSEL4 will be asserted too (I can see this using the scope). This is unreasonable according to HRM. Signed-off-by: Yi Li Signed-off-by: Bryan Wu --- drivers/spi/spi_bfin5xx.c | 5 ++--- 1 files changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 9c602ad..8cf5d6e 100644 --- a/drivers/spi/spi_bfin5xx.c +++ b/drivers/spi/spi_bfin5xx.c @@ -189,6 +189,7 @@ static void cs_deactive(struct driver_data *drv_data, struct chip_data *chip) { u16 flag = read_FLAG(drv_data); + flag &= ~chip->flag; flag |= (chip->flag << 8); write_FLAG(drv_data, flag); @@ -1032,7 +1033,6 @@ static int setup(struct spi_device *spi) struct bfin5xx_spi_chip *chip_info = NULL; struct chip_data *chip; struct driver_data *drv_data = spi_master_get_devdata(spi->master); - u8 spi_flg; /* Abort device setup if requested features are not supported */ if (spi->mode & ~(SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST)) { @@ -1115,8 +1115,7 @@ static int setup(struct spi_device *spi) * SPI_BAUD, not the real baudrate */ chip->baud = hz_to_spi_baud(spi->max_speed_hz); - spi_flg = ~(1 << (spi->chip_select)); - chip->flag = ((u16) spi_flg << 8) | (1 << (spi->chip_select)); + chip->flag = 1 << (spi->chip_select); chip->chip_select_num = spi->chip_select; switch (chip->bits_per_word) { -- 1.5.6.3 -- 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/