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

From: Hsin-Yi Wang
Date: Tue Nov 23 2021 - 06:21:15 EST

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

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@xxxxxxxxxxxx/
[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@xxxxxxxxxxxx/

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(-)