dmaengine: mmp_pdma: fix DMA mask handling

The driver's existing logic for setting the DMA mask for "marvell,pdma-1.0"
was flawed. It incorrectly relied on pdev->dev->coherent_dma_mask instead
of declaring the hardware's fixed addressing capability. A cleaner and
more correct approach is to define the mask directly based on the hardware
limitations.

The MMP/PXA PDMA controller is a 32-bit DMA engine. This is supported by
datasheets and various dtsi files for PXA25x, PXA27x, PXA3xx, and MMP2,
all of which are 32-bit systems.

This patch simplifies the driver's logic by replacing the 'u64 dma_mask'
field with a simpler 'u32 dma_width' to store the addressing capability
in bits. The complex if/else block in probe() is then replaced with a
single, clear call to dma_set_mask_and_coherent(). This sets a fixed
32-bit DMA mask for "marvell,pdma-1.0" and a 64-bit mask for
"spacemit,k1-pdma," matching each device's hardware capabilities.

Finally, this change also works around a specific build error encountered
with clang-20 on x86_64 allyesconfig. The shift-count-overflow error is
caused by a known clang compiler issue where the DMA_BIT_MASK(n) macro's
ternary operator is not correctly evaluated in static initializers. By
moving the macro's evaluation into the probe() function, the driver avoids
this compiler bug.

Fixes: 5cfe585d8624 ("dmaengine: mmp_pdma: Add SpacemiT K1 PDMA support with 64-bit addressing")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Closes: https://lore.kernel.org/lkml/CA+G9fYsPcMfW-e_0_TRqu4cnwqOqYF3aJOeKUYk6Z4qRStdFvg@mail.gmail.com
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Guodong Xu <guodong@riscstar.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Nathan Chancellor <nathan@kernel.org> # build
Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 8 insertions, 12 deletions

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index d07229a74886..86661eb3cde1 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -152,8 +152,8 @@ struct mmp_pdma_phy {
  *
  * Controller Configuration:
  * @run_bits:   Control bits in DCSR register for channel start/stop
- * @dma_mask:   DMA addressing capability of controller. 0 to use OF/platform
- *              settings, or explicit mask like DMA_BIT_MASK(32/64)
+ * @dma_width:  DMA addressing width in bits (32 or 64). Determines the
+ *              DMA mask capability of the controller hardware.
  */
 struct mmp_pdma_ops {
 	/* Hardware Register Operations */
@@ -173,7 +173,7 @@ struct mmp_pdma_ops {
 
 	/* Controller Configuration */
 	u32 run_bits;
-	u64 dma_mask;
+	u32 dma_width;
 };
 
 struct mmp_pdma_device {
@@ -1172,7 +1172,7 @@ static const struct mmp_pdma_ops marvell_pdma_v1_ops = {
 	.get_desc_src_addr = get_desc_src_addr_32,
 	.get_desc_dst_addr = get_desc_dst_addr_32,
 	.run_bits = (DCSR_RUN),
-	.dma_mask = 0,			/* let OF/platform set DMA mask */
+	.dma_width = 32,
 };
 
 static const struct mmp_pdma_ops spacemit_k1_pdma_ops = {
@@ -1185,7 +1185,7 @@ static const struct mmp_pdma_ops spacemit_k1_pdma_ops = {
 	.get_desc_src_addr = get_desc_src_addr_64,
 	.get_desc_dst_addr = get_desc_dst_addr_64,
 	.run_bits = (DCSR_RUN | DCSR_LPAEEN),
-	.dma_mask = DMA_BIT_MASK(64),	/* force 64-bit DMA addr capability */
+	.dma_width = 64,
 };
 
 static const struct of_device_id mmp_pdma_dt_ids[] = {
@@ -1314,13 +1314,9 @@ static int mmp_pdma_probe(struct platform_device *op)
 	pdev->device.directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
 	pdev->device.residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
 
-	/* Set DMA mask based on ops->dma_mask, or OF/platform */
-	if (pdev->ops->dma_mask)
-		dma_set_mask(pdev->dev, pdev->ops->dma_mask);
-	else if (pdev->dev->coherent_dma_mask)
-		dma_set_mask(pdev->dev, pdev->dev->coherent_dma_mask);
-	else
-		dma_set_mask(pdev->dev, DMA_BIT_MASK(64));
+	/* Set DMA mask based on controller hardware capabilities */
+	dma_set_mask_and_coherent(pdev->dev,
+				  DMA_BIT_MASK(pdev->ops->dma_width));
 
 	ret = dma_async_device_register(&pdev->device);
 	if (ret) {