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authorEmil Renner Berthing <emil.renner.berthing@canonical.com>2023-11-30 16:19:29 +0100
committerConor Dooley <conor.dooley@microchip.com>2023-12-13 16:50:23 +0100
commit0a99b562e81554c4397ba6331e9b00501c88b15c (patch)
treef15c4d4fb823826fae541b383c013a6093f4e510 /Documentation/mm
parentriscv: dts: starfive: Add JH7100 cache controller (diff)
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riscv: dts: starfive: Add pool for coherent DMA memory on JH7100 boards
The StarFive JH7100 SoC has non-coherent device DMAs, but most drivers expect to be able to allocate coherent memory for DMA descriptors and such. However on the JH7100 DDR memory appears twice in the physical memory map, once cached and once uncached: 0x00_8000_0000 - 0x08_7fff_ffff : Off chip DDR memory, cached 0x10_0000_0000 - 0x17_ffff_ffff : Off chip DDR memory, uncached To use this uncached region we create a global DMA memory pool there and reserve the corresponding area in the cached region. However the uncached region is fully above the 32bit address limit, so add a dma-ranges map so the DMA address used for peripherals is still in the regular cached region below the limit. Link: https://github.com/starfive-tech/JH7100_Docs/blob/main/JH7100%20Data%20Sheet%20V01.01.04-EN%20(4-21-2021).pdf Signed-off-by: Emil Renner Berthing <emil.renner.berthing@canonical.com> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
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