[PATCH 0/3] Allow restricted-dma-pool to customize IO_TLB_SEGSIZE

[Hsin-Yi Wang]

Default IO_TLB_SEGSIZE (128) slabs may be not enough for some use cases.
This series adds support to customize io_tlb_segsize for each
restricted-dma-pool.

Example use case:

mtk-isp drivers[1] are controlled by mtk-scp[2] and allocate memory through
mtk-scp. In order to use the noncontiguous DMA API[3], we need to use
the swiotlb pool. mtk-scp needs to allocate memory with 2560 slabs.
mtk-isp drivers also needs to allocate memory with 200+ slabs. Both are
larger than the default IO_TLB_SEGSIZE (128) slabs.

[1] (not in upstream) https://patchwork.kernel.org/project/linux-media/cover/20190611035344.29814-1-jungo.lin@mediatek.com/
[2] https://elixir.bootlin.com/linux/latest/source/drivers/remoteproc/mtk_scp.c
[3] https://patchwork.kernel.org/project/linux-media/cover/20210909112430.61243-1-senozhatsky@chromium.org/

Hsin-Yi Wang (3):
  dma: swiotlb: Allow restricted-dma-pool to customize IO_TLB_SEGSIZE
  dt-bindings: Add io-tlb-segsize property for restricted-dma-pool
  arm64: dts: mt8183: use restricted swiotlb for scp mem

 .../reserved-memory/shared-dma-pool.yaml      |  8 +++++
 .../arm64/boot/dts/mediatek/mt8183-kukui.dtsi |  4 +--
 include/linux/swiotlb.h                       |  1 +
 kernel/dma/swiotlb.c                          | 34 ++++++++++++++-----
 4 files changed, 37 insertions(+), 10 deletions(-)

-- 
2.34.0.rc2.393.gf8c9666880-goog