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 <[email protected]> Signed-off-by: Anatolij Gustschin <[email protected]> --- drivers/spi/spi-mpc512x-psc.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/spi/spi-mpc512x-psc.c b/drivers/spi/spi-mpc512x-psc.c index 6b600a2..dfddf33 100644 --- a/drivers/spi/spi-mpc512x-psc.c +++ b/drivers/spi/spi-mpc512x-psc.c @@ -168,7 +168,7 @@ 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--; -- 1.7.5.4 ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_mar _______________________________________________ spi-devel-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/spi-devel-general
