spi: mpc52xx_psc_spi chipselect bugfix
PATCH 1/1 spi: mpc52xx_psc_spi chipselect bugfix
From: Stefano Babic <[email protected]>
According to the manual the "tdfOnExit" flag must be set on the last byte we want to send. The PSC controller holds SS low until the flag is set.
However, the flag was set always on the last byte of the FIFO, independently if it is the last byte of the transfer. This generates spurious toggling of the SS signals that breaks the protocol of some peripherals. Fix.
--- drivers/spi/mpc52xx_psc_spi.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
drivers/spi/mpc52xx_psc_spi.c +4 -1
@@ -142,6 +142,7 @@ static int mpc52xx_psc_spi_transfer_rxtxunsigned rfalarm;unsigned send_at_once = MPC52xx_PSC_BUFSIZE;unsigned recv_at_once; +int last_block =0 ;if (!t->tx_buf && !t->rx_buf && t->len)return -EINVAL ;
@@ -151,15 +152,17 @@ static int mpc52xx_psc_spi_transfer_rxtxwhile (rb < t->len) {if (t->len - rb > MPC52xx_PSC_BUFSIZE) { rfalarm = MPC52xx_PSC_RFALARM; + last_block =0 ; }else { send_at_once = t->len - sb; rfalarm = MPC52xx_PSC_BUFSIZE - (t->len - rb); + last_block =1 ; }dev_dbg (&spi->dev,"send %d bytes...\n" , send_at_once);for (; send_at_once; sb++, send_at_once--) {/* set EOF flag before the last word is sent */ -if (send_at_once ==1 ) +if (send_at_once ==1 && last_block)out_8 (&psc->ircr2,0x01 );if (tx_buf)
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