From 1ad849aee5f53353ed88d9cd3d68a51b03a7d44f Mon Sep 17 00:00:00 2001 From: Anatolij Gustschin <agust@denx.de> Date: Wed, 13 Mar 2013 14:57:43 +0100 Subject: [PATCH] spi/mpc512x-psc: optionally keep PSC SS asserted across xfer segmensts Some SPI slave devices require asserted chip select signal across multiple transfer segments of an SPI message. Currently the driver always de-asserts the internal SS signal for every single transfer segment of the message and ignores the 'cs_change' flag of the transfer description. Disable the internal chip select (SS) only if this is needed and indicated by the 'cs_change' flag. Without this change, each partial transfer of a surrounding multi-part SPI transaction might erroneously change the SS signal, which might prevent slaves from answering the request that was sent in a previous transfer segment because the transaction could be considered aborted (SS was de-asserted before reading the response). Reported-by: Gerhard Sittig <gerhard.sittig@ifm.com> Signed-off-by: Anatolij Gustschin <agust@denx.de> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com> Cc: stable@vger.kernel.org --- drivers/spi/spi-mpc512x-psc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/spi/spi-mpc512x-psc.c b/drivers/spi/spi-mpc512x-psc.c index 89480b281d74..3e490ee7f275 100644 --- a/drivers/spi/spi-mpc512x-psc.c +++ b/drivers/spi/spi-mpc512x-psc.c @@ -164,7 +164,7 @@ static int mpc512x_psc_spi_transfer_rxtx(struct spi_device *spi, for (i = count; i > 0; i--) { data = tx_buf ? *tx_buf++ : 0; - if (len == EOFBYTE) + if (len == EOFBYTE && t->cs_change) setbits32(&fifo->txcmd, MPC512x_PSC_FIFO_EOF); out_8(&fifo->txdata_8, data); len--;