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@acm.org>
Fixes: cc52e15397cc ("scsi: ufs: ufs-exynos: Support ExynosAuto v9 UFS")
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://lore.kernel.org/r/20250319-exynos-ufs-stability-fixes-v2-3-96722cc2ba1b@linaro.org
Cc: Chanho Park <chanho61.park@samsung.com>
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/ufs/host/ufs-exynos.c b/drivers/ufs/host/ufs-exynos.c
index 1d4603f7622d186865ada738029e62cfe1fbfaca..533904a4c1a728856749f9a5cb02b90d7f76a473 100644 (file)
--- 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 ad49d9cdd5c122dc036ea5c6c66094525c044ca0..d0b3df221503c61d88702873054cec99139e049a 100644 (file)
--- 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)