linux-kernel - [PATCH] spi: dw-mmio: add error handling for reset_control

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Message-ID: <20251007101134.1912895-1-a.shimko.dev@gmail.com>
Date: Tue,  7 Oct 2025 13:11:33 +0300
From: Artem Shimko <a.shimko.dev@...il.com>
To: Mark Brown <broonie@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>
Cc: a.shimko.dev@...il.com,
	linux-spi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] spi: dw-mmio: add error handling for reset_control_deassert()

Currently reset_control_deassert() is called without checking its
return value. This can lead to silent failures when reset deassertion
fails.

Add proper error handling to:
1. Check the return value of reset_control_deassert()
2. Return the error to the caller
3. Provide meaningful error message using dev_err_probe()

This ensures that reset-related failures are properly reported during
probe and helps with debugging reset issues.

Signed-off-by: Artem Shimko <a.shimko.dev@...il.com>
---

This patch addresses an issue in the DesignWare SPI MMIO driver
where the return value of reset_control_deassert() was not being checked,
potentially leading to silent failures.

The problem occurs when reset deassertion fails - the driver would
continue probing without the device being properly reset, which could
result in unpredictable behavior or hardware malfunctions.

Patch adds proper error checking and propagation for the
reset_control_deassert() call, ensuring that probe fails gracefully
when reset operations cannot be completed successfully.

This change improves the robustness of the driver and provides better
debugging information when reset-related issues occur.

 drivers/spi/spi-dw-mmio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index f0f576fac77a..7a5197586919 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -358,7 +358,9 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 	if (IS_ERR(dwsmmio->rstc))
 		return PTR_ERR(dwsmmio->rstc);

-	reset_control_deassert(dwsmmio->rstc);
+	ret = reset_control_deassert(dwsmmio->rstc);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "Failed to deassert resets\n");

 	dws->bus_num = pdev->id;

-- 
2.43.0