[PATCH u-boot-marvell 10/11] arm: mvebu: turris_mox: Fix unstable board topology reading

Marek Behún kabel at kernel.org
Wed Nov 3 03:02:43 CET 2021

From: Marek Behún <marek.behun at nic.cz>

The pre-relocation board topology reading in board_fix_fdt() is
unstable: sometimes wrong data are read from the SPI bus.

This is due to wrong order of SPI bus configuration instructions: we
first need to set the pins to SPI mode, and only after that configure
the bus.

Also add a 1ms delay before enabling chip-select, so that the clock pin
is high for some time before reading the bus.

Signed-off-by: Marek Behún <marek.behun at nic.cz>
 board/CZ.NIC/turris_mox/turris_mox.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/board/CZ.NIC/turris_mox/turris_mox.c b/board/CZ.NIC/turris_mox/turris_mox.c
index 502f6fc010..809ce82d20 100644
--- a/board/CZ.NIC/turris_mox/turris_mox.c
+++ b/board/CZ.NIC/turris_mox/turris_mox.c
@@ -56,9 +56,11 @@ int board_fix_fdt(void *blob)
 	 * to read SPI by reading/writing SPI registers directly
-	writel(0x10df, ARMADA_37XX_SPI_CFG);
 	/* put pin from GPIO to SPI mode */
 	clrbits_le32(ARMADA_37XX_NB_GPIO_SEL, BIT(12));
+	/* configure cpol, cpha, prescale */
+	writel(0x10df, ARMADA_37XX_SPI_CFG);
+	mdelay(1);
 	/* enable SPI CS1 */
 	setbits_le32(ARMADA_37XX_SPI_CTRL, BIT(17));

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