From: Yi Li Date: Tue, 7 Apr 2009 02:00:49 +0000 (-0700) Subject: Blackfin SPI Driver: fix bug - correct usage of struct spi_transfer.cs_change X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=b9b2a76a4391cadb6d42da2ccf5e956c459acb72;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git Blackfin SPI Driver: fix bug - correct usage of struct spi_transfer.cs_change 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 Acked-by: David Brownell Cc: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c index 122292557bf3..bdad0bbd0a43 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", @@ -919,11 +918,11 @@ static void pump_transfers(unsigned long data) } else { /* Update total byte transfered */ message->actual_length += drv_data->len_in_bytes; - /* Move to next transfer of this msg */ message->state = next_transfer(drv_data); + if (drv_data->cs_change) + cs_deactive(drv_data, chip); } - /* Schedule next transfer tasklet */ tasklet_schedule(&drv_data->pump_transfers);