Re: [PATCH 05/15] pci: resource assignment based on p2p alignment

On Tue, Jul 17, 2012 at 01:05:47PM +0800, Ram Pai wrote:

On Tue, Jul 17, 2012 at 10:23:17AM +0800, Gavin Shan wrote:

quoted

The patch changes function pbus_size_io() and pbus_size_mem() to
do resource (I/O, memory and prefetchable memory) reassignment
based on the minimal alignments for the p2p bridge, which was
retrieved by function window_alignment().

Signed-off-by: Gavin Shan <redacted>
---
 drivers/pci/setup-bus.c |   13 +++++++++----
 1 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index c0fb9da..a29483a 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c

@@ -731,6 +731,7 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
 	struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO);
 	unsigned long size = 0, size0 = 0, size1 = 0;
 	resource_size_t children_add_size = 0;
+	resource_size_t io_align;

 	if (!b_res)
  		return;

@@ -756,13 +757,15 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
 				children_add_size += get_res_add_size(realloc_head, r);
 		}
 	}
+
+	io_align = window_alignment(bus, IORESOURCE_IO);

this should also be
	io_align = max(4096, window_alignment(bus, IORESOURCE_IO));

right?

quoted

 	size0 = calculate_iosize(size, min_size, size1,
-			resource_size(b_res), 4096);
+			resource_size(b_res), io_align);
 	if (children_add_size > add_size)
 		add_size = children_add_size;
 	size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 :
 		calculate_iosize(size, min_size, add_size + size1,
-			resource_size(b_res), 4096);
+			resource_size(b_res), io_align);
 	if (!size0 && !size1) {
 		if (b_res->start || b_res->end)
 			dev_info(&bus->self->dev, "disabling bridge window "

@@ -772,11 +775,11 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
 		return;
 	}
 	/* Alignment of the IO window is always 4K */
-	b_res->start = 4096;
+	b_res->start = io_align;
 	b_res->end = b_res->start + size0 - 1;
 	b_res->flags |= IORESOURCE_STARTALIGN;
 	if (size1 > size0 && realloc_head) {
-		add_to_list(realloc_head, bus->self, b_res, size1-size0, 4096);
+		add_to_list(realloc_head, bus->self, b_res, size1-size0, io_align);
 		dev_printk(KERN_DEBUG, &bus->self->dev, "bridge window "
 				 "%pR to [bus %02x-%02x] add_size %lx\n", b_res,
 				 bus->secondary, bus->subordinate, size1-size0);

@@ -875,6 +878,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 			min_align = align1 >> 1;
 		align += aligns[order];
 	}
+
+	min_align = max(min_align, window_alignment(bus, type));

  'type' can sometimes be (IORESOURCE_MEM | IORESOURCE_PREFETCH), which
  can lead to unpredictable results depending on how window_alignment()
  is implemented... Hence to be on the safer side I suggest

	min_align = max(min_align, window_alignment(bus, b_res->flags & mask));

While you are at it, can we move the min_align calculation into
a separate function?

Somewhat around the following patch

diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
index 8fa2d4b..426c8ad6 100644
--- a/drivers/pci/setup-bus.c
+++ b/drivers/pci/setup-bus.c

@@ -762,6 +762,25 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size,
 	}
 }
 
+static inline calculate_min_align(resource_size_t aligns *aligns, int max_order)
+{
+	resource_size_t align = 0;
+	resource_size_t min_align = 0;
+	int order;
+	for (order = 0; order <= max_order; order++) {
+		resource_size_t align1 = 1;
+
+		align1 <<= (order + 20);
+
+		if (!align)
+			min_align = align1;
+		else if (ALIGN(align + min_align, min_align) < align1)
+			min_align = align1 >> 1;
+		align += aligns[order];
+	}
+	return min_align;
+}
+
 /**
  * pbus_size_mem() - size the memory window of a given bus
  *

@@ -841,19 +860,9 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 				children_add_size += get_res_add_size(realloc_head, r);
 		}
 	}
-	align = 0;
-	min_align = 0;
-	for (order = 0; order <= max_order; order++) {
-		resource_size_t align1 = 1;
 
-		align1 <<= (order + 20);
+	min_align = calculate_min_align(aligns, max_order);
 
-		if (!align)
-			min_align = align1;
-		else if (ALIGN(align + min_align, min_align) < align1)
-			min_align = align1 >> 1;
-		align += aligns[order];
-	}
 	size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align);
 	if (children_add_size > add_size)
 		add_size = children_add_size;

@@ -880,6 +889,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
 	return 1;
 }

 RP