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authorThor Thayer <tthayer@opensource.altera.com>2014-11-06 13:54:27 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-12-06 15:55:38 -0800
commit46c6d8959b29007aff9a2ab45b8936768526d775 (patch)
parentac68f344285fba683a3eb1239109dafcef989406 (diff)
spi: dw: Fix dynamic speed change.
commit 0a8727e69778683495058852f783eeda141a754e upstream. An IOCTL call that calls spi_setup() and then dw_spi_setup() will overwrite the persisted last transfer speed. On each transfer, the SPI speed is compared to the last transfer speed to determine if the clock divider registers need to be updated (did the speed change?). This bug was observed with the spidev driver using spi-config to update the max transfer speed. This fix: Don't overwrite the persisted last transaction clock speed when updating the SPI parameters in dw_spi_setup(). On the next transaction, the new speed won't match the persisted last speed and the hardware registers will be updated. On initialization, the persisted last transaction clock speed will be 0 but will be updated after the first SPI transaction. Move zeroed clock divider check into clock change test because chip->clk_div is zero on startup and would cause a divide-by-zero error. The calculation was wrong as well (can't support odd #). Reported-by: Vlastimil Setka <setka@vsis.cz> Signed-off-by: Vlastimil Setka <setka@vsis.cz> Signed-off-by: Thor Thayer <tthayer@opensource.altera.com> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index e63d27013142..e543b80d610e 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -394,9 +394,6 @@ static void pump_transfers(unsigned long data)
chip = dws->cur_chip;
spi = message->spi;
- if (unlikely(!chip->clk_div))
- chip->clk_div = dws->max_freq / chip->speed_hz;
if (message->state == ERROR_STATE) {
message->status = -EIO;
goto early_exit;
@@ -437,7 +434,7 @@ static void pump_transfers(unsigned long data)
if (transfer->speed_hz) {
speed = chip->speed_hz;
- if (transfer->speed_hz != speed) {
+ if ((transfer->speed_hz != speed) || (!chip->clk_div)) {
speed = transfer->speed_hz;
if (speed > dws->max_freq) {
printk(KERN_ERR "MRST SPI0: unsupported"
@@ -659,7 +656,6 @@ static int dw_spi_setup(struct spi_device *spi)
dev_err(&spi->dev, "No max speed HZ parameter\n");
return -EINVAL;
- chip->speed_hz = spi->max_speed_hz;
chip->tmode = 0; /* Tx & Rx */
/* Default SPI mode is SCPOL = 0, SCPH = 0 */