swiotlb: Export swioltb_nr_tbl and utilize it as appropiate.

By default the io_tlb_nslabs is set to zero, and gets set to whatever value is passed in via swiotlb_init_with_tbl function. The default value passed in is 64MB. However, if the user provides the 'swiotlb=<nslabs>' the default value is ignored and the value provided by the user is used... Except when the SWIOTLB is used under Xen - there the default value of 64MB is used and the Xen-SWIOTLB has no mechanism to get the 'io_tlb_nslabs' filled out by setup_io_tlb_npages functions. This patch provides a function for the Xen-SWIOTLB to call to see if the io_tlb_nslabs is set and if so use that value. Signed-off-by: FUJITA Tomonori <[email protected]> Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
seken · Jun 6, 2011 · 5f98ecd · 5f98ecd
1 parent 61c4f2c
commit 5f98ecd
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Showing 3 changed files with 15 additions and 3 deletions.
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
@@ -147,9 +147,15 @@ void __init xen_swiotlb_init(int verbose)
 {
 	unsigned long bytes;
 	int rc;
-
-	xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
-	xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
+	unsigned long nr_tbl;
+
+	nr_tbl = swioltb_nr_tbl();
+	if (nr_tbl)
+		xen_io_tlb_nslabs = nr_tbl;
+	else {
+		xen_io_tlb_nslabs = (64 * 1024 * 1024 >> IO_TLB_SHIFT);
+		xen_io_tlb_nslabs = ALIGN(xen_io_tlb_nslabs, IO_TLB_SEGSIZE);
+	}
 
 	bytes = xen_io_tlb_nslabs << IO_TLB_SHIFT;
 

diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
@@ -24,6 +24,7 @@ extern int swiotlb_force;
 
 extern void swiotlb_init(int verbose);
 extern void swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose);
+extern unsigned long swioltb_nr_tbl(void);
 
 /*
  * Enumeration for sync targets

diff --git a/lib/swiotlb.c b/lib/swiotlb.c
@@ -110,6 +110,11 @@ setup_io_tlb_npages(char *str)
 __setup("swiotlb=", setup_io_tlb_npages);
 /* make io_tlb_overflow tunable too? */
 
+unsigned long swioltb_nr_tbl(void)
+{
+	return io_tlb_nslabs;
+}
+
 /* Note that this doesn't work with highmem page */
 static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev,
 				      volatile void *address)