[PATCH v4 02/14] mci: atmel_mci: fix zeroing of block length on AT91SAM9263

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

We don't read back ATMCI_MR, but instead set up the value once and keep
writing it on every reset. On the SAM9263, but not on the later SAM9x5,
the ATMCI_MR register also includes a field for the block length. Not
taking that into account means that we zero the block length on every
reset.

While the effect of this zeroing is likely limited, because we set the
block length on every transfer via ATMCI_BLKR, it would be less surprising
and more robust against future change to not intermittently zero the block
length via the MR register.

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
 drivers/mci/atmel_mci_common.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/mci/atmel_mci_common.c b/drivers/mci/atmel_mci_common.c
index 098e90503a3a..7b11e9134e65 100644
--- a/drivers/mci/atmel_mci_common.c
+++ b/drivers/mci/atmel_mci_common.c
@@ -68,7 +68,17 @@ static void atmci_set_clk_rate(struct atmel_mci *host,
 				 clock_min, host->bus_hz / (2 * 256));
 			clkdiv = 255;
 		}
-		host->mode_reg = ATMCI_MR_CLKDIV(clkdiv);
+
+		/*
+		 * Older Atmels without CLKODD have the block length
+		 * in the upper 16 bits of both MCI_MR and MCI_BLKR
+		 *
+		 * To avoid intermittent zeroing of the block length,
+		 * just hardcode 512 here and have atmci_setup_data()
+		 * change it as necessary.
+		 */
+
+		host->mode_reg = ATMCI_MR_CLKDIV(clkdiv) | ATMCI_BLKLEN(512);
 	}
 
 	dev_dbg(host->hw_dev, "atmel_set_clk_rate: clkIn=%ld clkIos=%d divider=%d\n",
-- 
2.39.2