| Message ID | 20230223113644.23356-6-jiaxun.yang@flygoat.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | Use dma_default_coherent for devicetree default coherency | expand |
> - select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE
Doesn't powerpc need to select CONFIG_ARCH_DMA_DEFAULT_COHERENT now,
or even better should be doing that in the patch adding that
symbol?
In fact I wonder if adding CONFIG_ARCH_DMA_DEFAULT_COHERENT and removing
OF_DMA_DEFAULT_COHERENT should be one patch, as that seems to bring
over the intent a little better I'd say.
> 2023年3月1日 13:06，Christoph Hellwig <hch@lst.de> 写道： > >> - select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE > > Doesn't powerpc need to select CONFIG_ARCH_DMA_DEFAULT_COHERENT now, > or even better should be doing that in the patch adding that > symbol? If I read the code correctly for powerpc OF_DMA_DEFAULT_COHERENT is only selected with !NOT_COHERENT_CACHE, which means non-coherent dma support is disabled…. > > In fact I wonder if adding CONFIG_ARCH_DMA_DEFAULT_COHERENT and removing > OF_DMA_DEFAULT_COHERENT should be one patch, as that seems to bring > over the intent a little better I'd say.
Jiaxun Yang <jiaxun.yang@flygoat.com> writes: >> 2023年3月1日 13:06，Christoph Hellwig <hch@lst.de> 写道： >> >>> - select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE >> >> Doesn't powerpc need to select CONFIG_ARCH_DMA_DEFAULT_COHERENT now, >> or even better should be doing that in the patch adding that >> symbol? > > If I read the code correctly for powerpc OF_DMA_DEFAULT_COHERENT is only selected > with !NOT_COHERENT_CACHE, which means non-coherent dma support is disabled…. I think you're right, but it's not easy to understand. powerpc's NOT_COHERENT_CACHE selects: select ARCH_HAS_DMA_PREP_COHERENT select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_HAS_SYNC_DMA_FOR_CPU Then in your patch 3 you do: #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \ defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \ defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) -bool dma_default_coherent; +bool dma_default_coherent = IS_ENABLED(CONFIG_ARCH_DMA_DEFAULT_COHERENT); #endif So for powerpc if NOT_COHERENT_CACHE=n, then none of those ARCH_HAS symbols are defined, and so CONFIG_ARCH_DMA_DEFAULT_COHERENT is never used. But like I said it's not very obvious, and it also seems fragile to future changes. So it seems it would be more future proof, and self documenting for powerpc to just have: select ARCH_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE cheers
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 2c9cdf1d8761..c67e5da714f7 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -272,7 +272,6 @@ config PPC select NEED_PER_CPU_PAGE_FIRST_CHUNK if PPC64 select NEED_SG_DMA_LENGTH select OF - select OF_DMA_DEFAULT_COHERENT if !NOT_COHERENT_CACHE select OF_EARLY_FLATTREE select OLD_SIGACTION if PPC32 select OLD_SIGSUSPEND diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index b71ce992c0c0..a79663191228 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -119,7 +119,6 @@ config RISCV select MODULES_USE_ELF_RELA if MODULES select MODULE_SECTIONS if MODULES select OF - select OF_DMA_DEFAULT_COHERENT select OF_EARLY_FLATTREE select OF_IRQ select PCI_DOMAINS_GENERIC if PCI diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 644386833a7b..e40f10bf2ba4 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -102,8 +102,4 @@ config OF_OVERLAY config OF_NUMA bool -config OF_DMA_DEFAULT_COHERENT - # arches should select this if DMA is coherent by default for OF devices - bool - endif # OF diff --git a/drivers/of/address.c b/drivers/of/address.c index c105d66a1fa4..23ade4919853 100644 --- a/drivers/of/address.c +++ b/drivers/of/address.c @@ -1103,15 +1103,7 @@ phys_addr_t __init of_dma_get_max_cpu_address(struct device_node *np) bool of_dma_is_coherent(struct device_node *np) { struct device_node *node; - bool is_coherent = IS_ENABLED(CONFIG_OF_DMA_DEFAULT_COHERENT); - - /* - * DT-based MIPS doesn't use OF_DMA_DEFAULT_COHERENT, but - * might override the system-wide default at runtime. - */ -#if defined(CONFIG_MIPS) && defined(CONFIG_DMA_NONCOHERENT) - is_coherent = dma_default_coherent; -#endif + bool is_coherent = dma_default_coherent; node = of_node_get(np);
As for now all arches have dma_default_coherent matched with default DMA coherency for of devices, so there is no need to have a standalone config option. Note for PowerPC: CONFIG_OF_DMA_DEFUALT_COHERENT was only selected when CONFIG_NOT_COHERENT_CACHE is false, in this case dma_default_coherent will be true, so it still matches present behavior. Note for RISCV: dma_default_coherent is set to true in this series. Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> --- arch/powerpc/Kconfig | 1 - arch/riscv/Kconfig | 1 - drivers/of/Kconfig | 4 ---- drivers/of/address.c | 10 +--------- 4 files changed, 1 insertion(+), 15 deletions(-)