[PATCH v2 0/3] Add DMA support for i.MX94 and improve AHB read performance

This series adds DMA support to the NXP XSPI controller on i.MX94
and enables the use of DMA for AHB read operations to improve
performance.

On i.MX943 EVK, the measured read throughput improves 4x higher, from
approximately 70 MB/s to 290 MB/s when DMA is used.

Changes in v2:
- Reorder the patch series.
- Adjust DT binding patch subject lines to match SPI subsystem conventions.
- Update commit message to include ~4x AHB read performance improvement.
- Rename DMA timeout macro to indicate time unit and document timeout selection.
- Simplify DMA channel initialization flow.
- Add CPU fallback path when DMA read fails.
- Clarify/fix DMA alignment handling based on DMA engine requirements.
- Drop unrelated formatting change in probe().

Signed-off-by: Han Xu <[email protected]>
---
Han Xu (3):
      spi: dt-bindings: nxp,imx94-xspi: add DMA properties
      spi: nxp-xspi: Improve AHB read performance with DMA
      arm64: dts: imx94-xspi: add the DMA channels

 .../devicetree/bindings/spi/nxp,imx94-xspi.yaml    |  10 ++
 arch/arm64/boot/dts/freescale/imx94.dtsi           |   4 +
 drivers/spi/spi-nxp-xspi.c                         | 130 ++++++++++++++++++++-
 3 files changed, 141 insertions(+), 3 deletions(-)
---
base-commit: 2c2900017f2486e7b46795e80d7c8f3f8fbe0236
change-id: 20260621-xspi_dma_upstream-324c07d4c116

Best regards,
--  
Han Xu <[email protected]>