linux-kernel - [PATCH v2] spi: cadence-quadspi: Parse DT for flashes with the rest of the DT parsing

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Message-Id: <20251204-spi-cadence-qspi-runtime-pm-imbalance-v2-1-10af9115d531@kernel.org>
Date: Thu, 04 Dec 2025 19:13:35 +0000
From: Mark Brown <broonie@...nel.org>
To: Francesco Dolcini <francesco@...cini.it>, 
 Siddharth Vadapalli <s-vadapalli@...com>, Anurag Dutta <a-dutta@...com>
Cc: linux-spi@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Mark Brown <broonie@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v2] spi: cadence-quadspi: Parse DT for flashes with the
 rest of the DT parsing

The recent refactoring of where runtime PM is enabled done in commit
f1eb4e792bb1 ("spi: spi-cadence-quadspi: Enable pm runtime earlier to
avoid imbalance") made the fact that when we do a pm_runtime_disable()
in the error paths of probe() we can trigger a runtime disable which in
turn results in duplicate clock disables.  This is particularly likely
to happen when there is missing or broken DT description for the flashes
attached to the controller.

Early on in the probe function we do a pm_runtime_get_noresume() since
the probe function leaves the device in a powered up state but in the
error path we can't assume that PM is enabled so we also manually
disable everything, including clocks. This means that when runtime PM is
active both it and the probe function release the same reference to the
main clock for the IP, triggering warnings from the clock subsystem:

[    8.693719] clk:75:7 already disabled
[    8.693791] WARNING: CPU: 1 PID: 185 at /usr/src/kernel/drivers/clk/clk.c:1188 clk_core_disable+0xa0/0xb
...
[    8.694261]  clk_core_disable+0xa0/0xb4 (P)
[    8.694272]  clk_disable+0x38/0x60
[    8.694283]  cqspi_probe+0x7c8/0xc5c [spi_cadence_quadspi]
[    8.694309]  platform_probe+0x5c/0xa4

Dealing with this issue properly is complicated by the fact that we
don't know if runtime PM is active so can't tell if it will disable the
clocks or not.  We can, however, sidestep the issue for the flash
descriptions by moving their parsing to when we parse the controller
properties which also save us doing a bunch of setup which can never be
used so let's do that.

Reported-by: Francesco Dolcini <francesco@...cini.it>
Closes: https://lore.kernel.org/r/20251201072844.GA6785@francesco-nb
Signed-off-by: Mark Brown <broonie@...nel.org>
Cc: stable@...r.kernel.org
---
Changes in v2:
- Switch to moving the DT parsing earlier so we avoid triggering the
  clock referencing problems.
- Link to v1: https://patch.msgid.link/20251202-spi-cadence-qspi-runtime-pm-imbalance-v1-1-aee8c7fa21f2@kernel.org
---
 drivers/spi/spi-cadence-quadspi.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index af6d050da1c8..bdbeef05cd72 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -1845,6 +1845,12 @@ static int cqspi_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}

+	ret = cqspi_setup_flash(cqspi);
+	if (ret) {
+		dev_err(dev, "failed to setup flash parameters %d\n", ret);
+		return ret;
+	}
+
 	/* Obtain QSPI clock. */
 	cqspi->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(cqspi->clk)) {
@@ -1988,12 +1994,6 @@ static int cqspi_probe(struct platform_device *pdev)
 		pm_runtime_get_noresume(dev);
 	}

-	ret = cqspi_setup_flash(cqspi);
-	if (ret) {
-		dev_err(dev, "failed to setup flash parameters %d\n", ret);
-		goto probe_setup_failed;
-	}
-
 	host->num_chipselect = cqspi->num_chipselect;

 	if (ddata && (ddata->quirks & CQSPI_SUPPORT_DEVICE_RESET))

---
base-commit: cebdea5fc60642a39a76c237257a7e6662336006
change-id: 20251202-spi-cadence-qspi-runtime-pm-imbalance-657740cf7eae

Best regards,
--  
Mark Brown <broonie@...nel.org>