From mboxrd@z Thu Jan 1 00:00:00 1970 From: Feng Tang Subject: [Patch v2 1/3] spi/dw_spi: Fix too short timeout in spi polling loop Date: Fri, 24 Dec 2010 13:59:09 +0800 Message-ID: <1293170351-7426-1-git-send-email-feng.tang@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Arjan van de Ven , linus.walleij-0IS4wlFg1OjSUeElwK9/Pw@public.gmane.org, alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org To: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org, dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org The SPI polling loop timeout only works with HZ=100 as the loop was actually too short. Also add appropriate cpu_relax() in the busy wait loops... Acked-by: Grant Likely Signed-off-by: Arjan van de Ven Signed-off-by: Alan Cox --- drivers/spi/dw_spi.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c index 0838c79..25238a8 100644 --- a/drivers/spi/dw_spi.c +++ b/drivers/spi/dw_spi.c @@ -164,20 +164,23 @@ static inline void mrst_spi_debugfs_remove(struct dw_spi *dws) static void wait_till_not_busy(struct dw_spi *dws) { - unsigned long end = jiffies + 1 + usecs_to_jiffies(1000); + unsigned long end = jiffies + 1 + usecs_to_jiffies(5000); while (time_before(jiffies, end)) { if (!(dw_readw(dws, sr) & SR_BUSY)) return; + cpu_relax(); } dev_err(&dws->master->dev, - "DW SPI: Status keeps busy for 1000us after a read/write!\n"); + "DW SPI: Status keeps busy for 5000us after a read/write!\n"); } static void flush(struct dw_spi *dws) { - while (dw_readw(dws, sr) & SR_RF_NOT_EMPT) + while (dw_readw(dws, sr) & SR_RF_NOT_EMPT) { dw_readw(dws, dr); + cpu_relax(); + } wait_till_not_busy(dws); } -- 1.7.0.4 ------------------------------------------------------------------------------ Learn how Oracle Real Application Clusters (RAC) One Node allows customers to consolidate database storage, standardize their database environment, and, should the need arise, upgrade to a full multi-node Oracle RAC database without downtime or disruption http://p.sf.net/sfu/oracle-sfdevnl