The patch titled
spi: mpc52xx_psc_spi chipselect bugfix
has been added to the -mm tree. Its filename is
spi-mpc52xx_psc_spi-chipselect-bugfix.patch
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Subject: spi: mpc52xx_psc_spi chipselect bugfix
From: Stefano Babic <sbabic@xxxxxxx>
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.
Signed-off-by: Stefano Babic <sbabic@xxxxxxx>
Acked-by: Grant Likely <grant.likely@xxxxxxxxxxxx>
Signed-off-by: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/spi/mpc52xx_psc_spi.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff -puN drivers/spi/mpc52xx_psc_spi.c~spi-mpc52xx_psc_spi-chipselect-bugfix drivers/spi/mpc52xx_psc_spi.c
--- a/drivers/spi/mpc52xx_psc_spi.c~spi-mpc52xx_psc_spi-chipselect-bugfix
+++ a/drivers/spi/mpc52xx_psc_spi.c
@@ -142,6 +142,7 @@ static int mpc52xx_psc_spi_transfer_rxtx
unsigned 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_rxtx
while (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)
_
Patches currently in -mm which might be from sbabic@xxxxxxx are
spi-mpc52xx_psc_spi-chipselect-bugfix.patch
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