OpenWrt – Rev 1
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From: Felix Fietkau <nbd@nbd.name>
Date: Tue, 5 Dec 2017 12:46:01 +0100
Subject: [PATCH] MIPS: mm: remove no-op dma_map_ops where possible
If no post-DMA flush is required, and the platform does not provide
plat_unmap_dma_mem(), there is no need to include unmap or sync_for_cpu
ops.
With this patch they are compiled out to improve icache footprint
on devices that handle lots of DMA traffic (especially network routers).
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -214,6 +214,7 @@ config BMIPS_GENERIC
select BRCMSTB_L2_IRQ
select IRQ_MIPS_CPU
select DMA_NONCOHERENT
+ select DMA_UNMAP_POST_FLUSH
select SYS_SUPPORTS_32BIT_KERNEL
select SYS_SUPPORTS_LITTLE_ENDIAN
select SYS_SUPPORTS_BIG_ENDIAN
@@ -339,6 +340,7 @@ config MACH_JAZZ
select CSRC_R4K
select DEFAULT_SGI_PARTITION if CPU_BIG_ENDIAN
select GENERIC_ISA_DMA
+ select DMA_UNMAP_POST_FLUSH
select HAVE_PCSPKR_PLATFORM
select IRQ_MIPS_CPU
select I8253
@@ -1129,6 +1131,9 @@ config DMA_NONCOHERENT
bool
select NEED_DMA_MAP_STATE
+config DMA_UNMAP_POST_FLUSH
+ bool
+
config NEED_DMA_MAP_STATE
bool
@@ -1653,6 +1658,7 @@ config CPU_R10000
select CPU_SUPPORTS_64BIT_KERNEL
select CPU_SUPPORTS_HIGHMEM
select CPU_SUPPORTS_HUGEPAGES
+ select DMA_UNMAP_POST_FLUSH
help
MIPS Technologies R10000-series processors.
@@ -1898,9 +1904,11 @@ config SYS_HAS_CPU_MIPS32_R3_5
bool
config SYS_HAS_CPU_MIPS32_R5
+ select DMA_UNMAP_POST_FLUSH
bool
config SYS_HAS_CPU_MIPS32_R6
+ select DMA_UNMAP_POST_FLUSH
bool
config SYS_HAS_CPU_MIPS64_R1
@@ -1910,6 +1918,7 @@ config SYS_HAS_CPU_MIPS64_R2
bool
config SYS_HAS_CPU_MIPS64_R6
+ select DMA_UNMAP_POST_FLUSH
bool
config SYS_HAS_CPU_R3000
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -290,8 +290,9 @@ static inline void __dma_sync(struct pag
} while (left);
}
-static void mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr,
- size_t size, enum dma_data_direction direction, unsigned long attrs)
+static void __maybe_unused
+mips_dma_unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
+ enum dma_data_direction direction, unsigned long attrs)
{
if (cpu_needs_post_dma_flush(dev))
__dma_sync(dma_addr_to_page(dev, dma_addr),
@@ -330,9 +331,10 @@ static dma_addr_t mips_dma_map_page(stru
return plat_map_dma_mem_page(dev, page) + offset;
}
-static void mips_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
- int nhwentries, enum dma_data_direction direction,
- unsigned long attrs)
+static void __maybe_unused
+mips_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
+ int nhwentries, enum dma_data_direction direction,
+ unsigned long attrs)
{
int i;
struct scatterlist *sg;
@@ -346,8 +348,9 @@ static void mips_dma_unmap_sg(struct dev
}
}
-static void mips_dma_sync_single_for_cpu(struct device *dev,
- dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
+static void __maybe_unused
+mips_dma_sync_single_for_cpu(struct device *dev, dma_addr_t dma_handle,
+ size_t size, enum dma_data_direction direction)
{
if (cpu_needs_post_dma_flush(dev))
__dma_sync(dma_addr_to_page(dev, dma_handle),
@@ -363,9 +366,9 @@ static void mips_dma_sync_single_for_dev
dma_handle & ~PAGE_MASK, size, direction);
}
-static void mips_dma_sync_sg_for_cpu(struct device *dev,
- struct scatterlist *sglist, int nelems,
- enum dma_data_direction direction)
+static void __maybe_unused
+mips_dma_sync_sg_for_cpu(struct device *dev, struct scatterlist *sglist,
+ int nelems, enum dma_data_direction direction)
{
int i;
struct scatterlist *sg;
@@ -415,12 +418,14 @@ static struct dma_map_ops mips_default_d
.free = mips_dma_free_coherent,
.mmap = mips_dma_mmap,
.map_page = mips_dma_map_page,
- .unmap_page = mips_dma_unmap_page,
.map_sg = mips_dma_map_sg,
+#ifdef CONFIG_DMA_UNMAP_POST_FLUSH
+ .unmap_page = mips_dma_unmap_page,
.unmap_sg = mips_dma_unmap_sg,
.sync_single_for_cpu = mips_dma_sync_single_for_cpu,
- .sync_single_for_device = mips_dma_sync_single_for_device,
.sync_sg_for_cpu = mips_dma_sync_sg_for_cpu,
+#endif
+ .sync_single_for_device = mips_dma_sync_single_for_device,
.sync_sg_for_device = mips_dma_sync_sg_for_device,
.dma_supported = mips_dma_supported
};