riscv: Only initialize swiotlb when necessary

The SWIOTLB buffer is not needed unless the physical address space
is beyond the limit of dma, only initialize swiotlb when swiotlb_force
is true or not all system memory is DMA-able.

Also move the swiotlb_init() into mem_init().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 4db4d0b..5c6d2a1 100644 (file)
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -17,7 +17,6 @@
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
 #include <linux/sched/task.h>
-#include <linux/swiotlb.h>
 #include <linux/smp.h>
 #include <linux/efi.h>
 #include <linux/crash_dump.h>
@@ -295,10 +294,6 @@ void __init setup_arch(char **cmdline_p)
                protect_kernel_linear_mapping_text_rodata();
        }
 
-#ifdef CONFIG_SWIOTLB
-       swiotlb_init(1);
-#endif
-
 #ifdef CONFIG_KASAN
        kasan_init();
 #endif

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index e7b136a..30b2045 100644 (file)
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -11,6 +11,7 @@
 #include <linux/memblock.h>
 #include <linux/initrd.h>
 #include <linux/swap.h>
+#include <linux/swiotlb.h>
 #include <linux/sizes.h>
 #include <linux/of_fdt.h>
 #include <linux/of_reserved_mem.h>
@@ -109,6 +110,13 @@ void __init mem_init(void)
        BUG_ON(!mem_map);
 #endif /* CONFIG_FLATMEM */
 
+#ifdef CONFIG_SWIOTLB
+       if (swiotlb_force == SWIOTLB_FORCE ||
+           max_pfn > PFN_DOWN(dma32_phys_limit))
+               swiotlb_init(1);
+       else
+               swiotlb_force = SWIOTLB_NO_FORCE;
+#endif
        high_memory = (void *)(__va(PFN_PHYS(max_low_pfn)));
        memblock_free_all();