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dmaengine: mmp_pdma: fix DMA mask handling

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[ Upstream commit 49400b701e ]

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: 5cfe585d86 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Guodong Xu 2025-09-18 22:27:27 +08:00 • committed by Greg Kroah-Hartman
commit 974f241095
1 changed files with 8 additions and 12 deletions
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