[PATCH v4 05/11] swiotlb: add swiotlb_set_default_size()
From: Albert Herranz <hidden>
Date: 2010-03-12 19:13:36
Also in:
lkml
Subsystem:
dma mapping helpers, library code, the rest · Maintainers:
Marek Szyprowski, Andrew Morton, Linus Torvalds
The current SWIOTLB code uses a default of 64MB for the IO TLB area. This size can be influenced using a kernel command line parameter "swiotlb". Unfortunately, the parsing of the kernel command line is done _after_ the swiotlb is initialized on some architectures. This patch adds a new function swiotlb_set_default_size() which can be used before swiotlb_init() to indicate the desired IO TLB area size in bytes. This will be used later to implement a smaller IO TLB on the Nintendo Wii video game console which just comes with 24MB + 64MB of RAM. CC: linuxppc-dev@lists.ozlabs.org CC: linux-kernel@vger.kernel.org CC: x86@kernel.org CC: linux-ia64@vger.kernel.org Signed-off-by: Albert Herranz <redacted> --- include/linux/swiotlb.h | 2 ++ lib/swiotlb.c | 20 ++++++++++++++++++++ 2 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 3954228..2af6a45 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h@@ -22,6 +22,8 @@ extern int swiotlb_force; */ #define IO_TLB_SHIFT 11 +extern size_t __init swiotlb_set_default_size(size_t size); + extern void swiotlb_init(int verbose); extern void *swiotlb_alloc_boot(size_t bytes, unsigned long nslabs);
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index 8f2dad9..dbeca50 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c@@ -117,6 +117,26 @@ setup_io_tlb_npages(char *str) __setup("swiotlb=", setup_io_tlb_npages); /* make io_tlb_overflow tunable too? */ +/** + * swiotlb_set_default_size() - set the default size for the IO TLB + * @size: size in bytes of the IO TLB + * + * A platform can use this function to change the default size of the + * IO TLB when the default of 64MB is not suitable. + * This function must be called before swiotlb_init(). + * + * Note that on some platforms this is the only way to influence the + * size of the IO TLB, as the command line may be parsed _after_ the + * IO TLB is initialized. + */ +size_t __init swiotlb_set_default_size(size_t size) +{ + size_t previous_size = io_tlb_nslabs << IO_TLB_SHIFT; + + io_tlb_nslabs = size >> IO_TLB_SHIFT; + return previous_size; +} + void * __weak __init swiotlb_alloc_boot(size_t size, unsigned long nslabs) { return alloc_bootmem_low_pages(size);
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