linux-kernel - [PATCH v2 3/7] scsi: ufs: exynos: disable iocc if dma-coherent property isn't set

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Message-Id: <20250319-exynos-ufs-stability-fixes-v2-3-96722cc2ba1b@linaro.org>
Date: Wed, 19 Mar 2025 15:30:20 +0000
From: Peter Griffin <peter.griffin@...aro.org>
To: Alim Akhtar <alim.akhtar@...sung.com>, 
 "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>, 
 "Martin K. Petersen" <martin.petersen@...cle.com>, 
 Krzysztof Kozlowski <krzk@...nel.org>, 
 Chanho Park <chanho61.park@...sung.com>
Cc: linux-scsi@...r.kernel.org, linux-samsung-soc@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>, 
 Eric Biggers <ebiggers@...nel.org>, Bart Van Assche <bvanassche@....org>, 
 willmcvicker@...gle.com, kernel-team@...roid.com, tudor.ambarus@...aro.org, 
 andre.draszik@...aro.org, Peter Griffin <peter.griffin@...aro.org>, 
 stable@...r.kernel.org
Subject: [PATCH v2 3/7] scsi: ufs: exynos: disable iocc if dma-coherent
 property isn't set

If dma-coherent property isn't set then descriptors are non-cacheable
and the iocc shareability bits should be disabled. Without this UFS
can end up in an incompatible configuration and suffer from random
cache related stability issues.

Suggested-by: Bart Van Assche <bvanassche@....org>
Fixes: cc52e15397cc ("scsi: ufs: ufs-exynos: Support ExynosAuto v9 UFS")
Signed-off-by: Peter Griffin <peter.griffin@...aro.org>
Cc: Chanho Park <chanho61.park@...sung.com>
Cc: stable@...r.kernel.org
---
 drivers/ufs/host/ufs-exynos.c | 17 +++++++++++++----
 drivers/ufs/host/ufs-exynos.h |  3 ++-
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/ufs/host/ufs-exynos.c b/drivers/ufs/host/ufs-exynos.c
index f393d42a659f821225e67e3e5d323478456ca3af..61b03e493cc1ddba17179a9f22e5b59ece02458b 100644
--- a/drivers/ufs/host/ufs-exynos.c
+++ b/drivers/ufs/host/ufs-exynos.c
@@ -214,8 +214,8 @@ static int exynos_ufs_shareability(struct exynos_ufs *ufs)
 	/* IO Coherency setting */
 	if (ufs->sysreg) {
 		return regmap_update_bits(ufs->sysreg,
-					  ufs->shareability_reg_offset,
-					  ufs->iocc_mask, ufs->iocc_mask);
+					  ufs->iocc_offset,
+					  ufs->iocc_mask, ufs->iocc_val);
 	}

 	return 0;
@@ -1173,13 +1173,22 @@ static int exynos_ufs_parse_dt(struct device *dev, struct exynos_ufs *ufs)
 		ufs->sysreg = NULL;
 	else {
 		if (of_property_read_u32_index(np, "samsung,sysreg", 1,
-					       &ufs->shareability_reg_offset)) {
+					       &ufs->iocc_offset)) {
 			dev_warn(dev, "can't get an offset from sysreg. Set to default value\n");
-			ufs->shareability_reg_offset = UFS_SHAREABILITY_OFFSET;
+			ufs->iocc_offset = UFS_SHAREABILITY_OFFSET;
 		}
 	}

 	ufs->iocc_mask = ufs->drv_data->iocc_mask;
+	/*
+	 * no 'dma-coherent' property means the descriptors are
+	 * non-cacheable so iocc shareability should be disabled.
+	 */
+	if (of_dma_is_coherent(dev->of_node))
+		ufs->iocc_val = ufs->iocc_mask;
+	else
+		ufs->iocc_val = 0;
+
 	ufs->pclk_avail_min = PCLK_AVAIL_MIN;
 	ufs->pclk_avail_max = PCLK_AVAIL_MAX;

diff --git a/drivers/ufs/host/ufs-exynos.h b/drivers/ufs/host/ufs-exynos.h
index 17696b3768debd641188b5089585b6d303de7451..a345809af79dc528ad518d3572fe8be034341ee0 100644
--- a/drivers/ufs/host/ufs-exynos.h
+++ b/drivers/ufs/host/ufs-exynos.h
@@ -231,8 +231,9 @@ struct exynos_ufs {
 	ktime_t entry_hibern8_t;
 	const struct exynos_ufs_drv_data *drv_data;
 	struct regmap *sysreg;
-	u32 shareability_reg_offset;
+	u32 iocc_offset;
 	u32 iocc_mask;
+	u32 iocc_val;

 	u32 opts;
 #define EXYNOS_UFS_OPT_HAS_APB_CLK_CTRL		BIT(0)

-- 
2.49.0.rc1.451.g8f38331e32-goog