From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bryan Wu Subject: [PATCH 16/16] Blackfin SPI Driver: fix bug - correct usage of struct spi_transfer.cs_change Date: Tue, 18 Nov 2008 15:52:40 +0800 Message-ID: <1226994760-4301-17-git-send-email-cooloney@kernel.org> References: <1226994760-4301-1-git-send-email-cooloney@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Yi Li , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: dbrownell-Rn4VEauK+AKRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Return-path: In-Reply-To: <1226994760-4301-1-git-send-email-cooloney-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> 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 From: Yi Li According to comments in linux/spi/spi.h: * All SPI transfers start with the relevant chipselect active. Normally * it stays selected until after the last transfer in a message. Drivers * can affect the chipselect signal using cs_change. * * (i) If the transfer isn't the last one in the message, this flag is * used to make the chipselect briefly go inactive in the middle of the * message. Toggling chipselect in this way may be needed to terminate * a chip command, letting a single spi_message perform all of group of * chip transactions together. * * (ii) When the transfer is the last one in the message, the chip may * stay selected until the next transfer. On multi-device SPI busses * with nothing blocking messages going to other devices, this is just * a performance hint; starting a message to another device deselects * this one. But in other cases, this can be used to ensure correctness. * Some devices need protocol transactions to be built from a series of * spi_message submissions, where the content of one message is determined * by the results of previous messages and where the whole transaction * ends when the chipselect goes intactive. Signed-off-by: Yi Li Signed-off-by: Bryan Wu --- drivers/spi/spi_bfin5xx.c | 15 ++++++++------- 1 files changed, 8 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 8cf5d6e..0e3102a 100644 --- a/drivers/spi/spi_bfin5xx.c +++ b/drivers/spi/spi_bfin5xx.c @@ -540,15 +540,13 @@ static void giveback(struct driver_data *drv_data) msg->state = NULL; - /* disable chip select signal. And not stop spi in autobuffer mode */ - if (drv_data->tx_dma != 0xFFFF) { - cs_deactive(drv_data, chip); - bfin_spi_disable(drv_data); - } - if (!drv_data->cs_change) cs_deactive(drv_data, chip); + /* Not stop spi in autobuffer mode */ + if (drv_data->tx_dma != 0xFFFF) + bfin_spi_disable(drv_data); + if (msg->complete) msg->complete(msg->context); } @@ -757,7 +755,8 @@ static void pump_transfers(unsigned long data) write_STAT(drv_data, BIT_STAT_CLR); cr = (read_CTRL(drv_data) & (~BIT_CTL_TIMOD)); - cs_active(drv_data, chip); + if (drv_data->cs_change) + cs_active(drv_data, chip); dev_dbg(&drv_data->pdev->dev, "now pumping a transfer: width is %d, len is %d\n", @@ -920,6 +919,8 @@ static void pump_transfers(unsigned long data) message->state = next_transfer(drv_data); } + if (drv_data->cs_change) + cs_active(drv_data, chip); /* Schedule next transfer tasklet */ tasklet_schedule(&drv_data->pump_transfers); -- 1.5.6.3 ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/