[PATCH] spi: Update speed/mode on change

[Marek Vasut]

The spi_get_bus_and_cs() may be called on the same bus and chipselect
with different frequency or mode. This is valid usecase, but the code
fails to notify the controller of such a configuration change. Call
spi_set_speed_mode() in case bus frequency or bus mode changed to let
the controller update the configuration.

The problem can easily be triggered using the sspi command:
=> sspi 0:0 at 1000
=> sspi 0:0 at 2000
Without this patch, both transfers happen at 1000 Hz. With this patch,
the later transfer happens correctly at 2000 Hz.

Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Jagan Teki <jagan at amarulasolutions.com>
Cc: Patrick Delaunay <patrick.delaunay at st.com>
---
 drivers/spi/spi-uclass.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
index 7155d4aebd6..96c9a83e761 100644
--- a/drivers/spi/spi-uclass.c
+++ b/drivers/spi/spi-uclass.c
@@ -405,12 +405,22 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
 			goto err;
 	}
 
+	/* In case bus frequency or mode changed, update it. */
+	if ((speed && slave->speed && slave->speed != speed) ||
+	    (plat->mode != mode)) {
+		ret = spi_set_speed_mode(bus, speed, mode);
+		if (ret)
+			goto err_speed_mode;
+	}
+
 	*busp = bus;
 	*devp = slave;
 	log_debug("%s: bus=%p, slave=%p\n", __func__, bus, *devp);
 
 	return 0;
 
+err_speed_mode:
+	spi_claim_bus(slave);
 err:
 	log_debug("%s: Error path, created=%d, device '%s'\n", __func__,
 		  created, dev->name);
-- 
2.30.0