[PATCH 2/2] qspi: t210: Fix QSPI clock and tap delays

[twarren at nvidia.com]

From: Tom Warren <twarren at nvidia.com>

When claim_bus was setting the clock, it reset the QSPI controller,
which wipes out any tap delays set by previous bootloaders (nvtboot,
CBoot for example on Nano). Instead of doing that in claim_bus, which
gets called a lot, moved clock setting to probe(), and set tap delays
there, too. Also updated clock to 80MHz to match CBoot. Now QSPI env
save will work reliably again on Nano.

Signed-off-by: Tom Warren <twarren at nvidia.com>
---
 drivers/spi/tegra210_qspi.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/drivers/spi/tegra210_qspi.c b/drivers/spi/tegra210_qspi.c
index 2a77126..4284ea9 100644
--- a/drivers/spi/tegra210_qspi.c
+++ b/drivers/spi/tegra210_qspi.c
@@ -42,10 +42,10 @@ DECLARE_GLOBAL_DATA_PTR;
 #define QSPI_CMD1_BITLEN_SHIFT		0
 
 /* COMMAND2 */
-#define QSPI_CMD2_TX_CLK_TAP_DELAY	BIT(6)
-#define QSPI_CMD2_TX_CLK_TAP_DELAY_MASK	GENMASK(11,6)
-#define QSPI_CMD2_RX_CLK_TAP_DELAY	BIT(0)
-#define QSPI_CMD2_RX_CLK_TAP_DELAY_MASK	GENMASK(5,0)
+#define QSPI_CMD2_TX_CLK_TAP_DELAY_SHIFT	10
+#define QSPI_CMD2_TX_CLK_TAP_DELAY_MASK	GENMASK(14,10)
+#define QSPI_CMD2_RX_CLK_TAP_DELAY_SHIFT	0
+#define QSPI_CMD2_RX_CLK_TAP_DELAY_MASK	GENMASK(7,0)
 
 /* TRANSFER STATUS */
 #define QSPI_XFER_STS_RDY		BIT(30)
@@ -127,14 +127,22 @@ static int tegra210_qspi_probe(struct udevice *bus)
 	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
 
 	priv->regs = (struct qspi_regs *)plat->base;
+	struct qspi_regs *regs = priv->regs;
 
 	priv->last_transaction_us = timer_get_us();
 	priv->freq = plat->frequency;
 	priv->periph_id = plat->periph_id;
 
+	debug("%s: Freq = %u, id = %d\n", __func__, priv->freq, priv->periph_id);
 	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
 	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);
 
+	/* Set tap delays here, clock change above resets QSPI controller */
+	u32 reg = (0x09 << QSPI_CMD2_TX_CLK_TAP_DELAY_SHIFT) |
+		   (0x0C << QSPI_CMD2_RX_CLK_TAP_DELAY_SHIFT);
+	writel(reg, &regs->command2);
+	debug("%s: COMMAND2 = %08x\n", __func__, readl(&regs->command2));
+
 	return 0;
 }
 
@@ -144,9 +152,6 @@ static int tegra210_qspi_claim_bus(struct udevice *dev)
 	struct tegra210_qspi_priv *priv = dev_get_priv(bus);
 	struct qspi_regs *regs = priv->regs;
 
-	/* Change SPI clock to correct frequency, PLLP_OUT0 source */
-	clock_start_periph_pll(priv->periph_id, CLOCK_ID_PERIPH, priv->freq);
-
 	debug("%s: FIFO STATUS = %08x\n", __func__, readl(&regs->fifo_status));
 
 	/* Set master mode and sw controlled CS */
-- 
1.8.2.1.610.g562af5b


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