[PATCH v7 14/18] spi: cadence-quadspi: reprogram PHY DLL on runtime resume

[Santhosh Kumar K <s-k6@ti.com>]

The PHY DLL loses its programmed delay values and lock when the OSPI
controller is power-gated during runtime suspend. On resume,
cqspi_controller_init() reinitialises the controller but does not
touch the PHY DLL registers, leaving the DLL in an unlocked state.
Any subsequent PHY read or write would then fail at the cqspi_resync_dll()
call inside cqspi_tune_phy().

After the controller re-initialisation, iterate over all chip selects
and reprogram the DLL with each CS's stored calibrated RX/TX tap counts,
then resync to relock it. One invocation per calibrated CS allows each
calibration to be independently validated after resume. DLL resync
failure is non-fatal: a warning is emitted and resume continues, so the
system degrades to non-PHY speed rather than blocking the resume path.

Signed-off-by: Santhosh Kumar K <s-k6@ti.com>
---
 drivers/spi/spi-cadence-quadspi.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index d4181b501d8d..c78d4ce1c930 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -4017,7 +4017,7 @@ static int cqspi_runtime_suspend(struct device *dev)
 static int cqspi_runtime_resume(struct device *dev)
 {
 	struct cqspi_st *cqspi = dev_get_drvdata(dev);
-	int ret;
+	int cs, ret;
 
 	ret = clk_bulk_prepare_enable(CLK_QSPI_NUM, cqspi->clks);
 	if (ret)
@@ -4030,6 +4030,23 @@ static int cqspi_runtime_resume(struct device *dev)
 
 	cqspi->current_cs = -1;
 	cqspi->sclk = 0;
+
+	for (cs = 0; cs < CQSPI_MAX_CHIPSELECT; cs++) {
+		struct cqspi_flash_pdata *f_pdata = &cqspi->f_pdata[cs];
+
+		if (!f_pdata->use_tuned_phy)
+			continue;
+
+		cqspi_phy_set_dll_master(cqspi);
+
+		cqspi_set_dll(cqspi->iobase, f_pdata->phy_setting.rx,
+			      f_pdata->phy_setting.tx);
+		ret = cqspi_resync_dll(cqspi);
+		if (ret)
+			dev_warn(dev, "cs%d: PHY DLL resync failed on resume: %d\n",
+				 cs, ret);
+	}
+
 	return 0;
 }
 
-- 
2.34.1