Problem with spi_device->max_speed_hz = 0 on atmel_spi driver.

Problem with spi_device->max_speed_hz = 0 on atmel_spi driver.

[Stanislaw Gruszka]

Hi.

For some reason I have to slowdown clock to touchscreen device.

In atmel_spi_setup() there is comment that max_speed_hz == 0 
means as slow as possible and divider is set to maximum value.
But in atmel_spi_transfer() function is check against not zero 
max_speed_hz with EINVAL returned. 

Probably driver should setup divider for each transfer based 
on transfer->speed_hz value, but I think that would be not
necessary overhead as all used devices have constant clock. 

Below patch works fine for me.

Signed-off-by: Stanislaw Gruszka <stf_xl-5tc4TXWwyLM@public.gmane.org>
diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
index 8abae4a..eec8f11 100644
--- a/drivers/spi/atmel_spi.c
+++ b/drivers/spi/atmel_spi.c
@@ -626,8 +626,7 @@ static int atmel_spi_transfer(struct spi_device *spi, struct spi_message *msg)
 	dev_dbg(controller, "new message %p submitted for %s\n",
 			msg, spi->dev.bus_id);
 
-	if (unlikely(list_empty(&msg->transfers)
-			|| !spi->max_speed_hz))
+	if (unlikely(list_empty(&msg->transfers)))
 		return -EINVAL;
 
 	if (as->stopping)


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