Re: Assign mem resource fail after remove and rescan

[Yinghai Lu <yinghai@kernel.org>]

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On Mon, Mar 30, 2015 at 11:38 PM, Yijing Wang <wangyijing@huawei.com> wrote:
> On 2015/3/29 14:18, Yinghai Lu wrote:
>> On Sat, Mar 28, 2015 at 3:02 AM, Yijing Wang <wangyijing@huawei.com> wrote:
>>> ...
>>>
>>> I compared above log and found after we did remove and rescan, the bridge requested resource size extended to 0x06000000,
>>> and when system boot up, it requested only 0x4800000.
>>>
>    I tested it, remove and rescan 05:19.0 device is ok now, but
> if do the operations for the parent device of 05:19.0, the result is
> still fail.

Found the problem, attached patch should fix the problem.

Thanks

Yinghai

[-- Attachment #2: pci_new_align_size_rule.patch --]
[-- Type: text/x-patch, Size: 4223 bytes --]

Subject: [PATCH] PCI: Optimize bus mem sizing to small size

Current code try to get min_align as possible and use that to
align final size.

That could cause generate wrong align/size or too big size in some case.

 when we have align/size: 16M/64M
 min_align/size0 will be 8M/64M, that is wrong, align must be 16M.

 when we have align/size: 1M/1M, 64M/64M,
 min_align/size0 will be 32M/96M, that is way too big for sum size 65M.

That will cuase allocation fails.

The patch introduce max_align/size0_max, and size0_max is just
sum of all children resource.

Prefer small size instead of small align. Only use min_align when
two size is the same.

The new size will only need to be aligned to bus window alignment.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>

---
 drivers/pci/setup-bus.c |   50 +++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 47 insertions(+), 3 deletions(-)

Index: linux-2.6/drivers/pci/setup-bus.c
===================================================================
--- linux-2.6.orig/drivers/pci/setup-bus.c
+++ linux-2.6/drivers/pci/setup-bus.c
@@ -882,12 +882,14 @@ static void pbus_size_io(struct pci_bus
 	}
 
 	size0 = calculate_iosize(size, min_size, size1,
-			resource_size(b_res), min_align);
+				 resource_size(b_res),
+				 window_alignment(bus, IORESOURCE_IO));
 	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), min_align);
+				 resource_size(b_res),
+				 window_alignment(bus, IORESOURCE_IO));
 	if (!size0 && !size1) {
 		if (b_res->start || b_res->end)
 			dev_info(&bus->self->dev, "disabling bridge window %pR to %pR (unused)\n",
@@ -962,6 +964,8 @@ static int pbus_size_mem(struct pci_bus
 	struct resource *b_res = find_free_bus_resource(bus,
 					mask | IORESOURCE_PREFETCH, type);
 	resource_size_t children_add_size = 0;
+	resource_size_t max_align = 0, size0_max;
+	int count = 0;
 
 	if (!b_res)
 		return -ENOSPC;
@@ -1016,19 +1020,59 @@ static int pbus_size_mem(struct pci_bus
 			if (order > max_order)
 				max_order = order;
 
+			count++;
+			if (align > max_align)
+				max_align = align;
+
 			if (realloc_head)
 				children_add_size += get_res_add_size(realloc_head, r);
 		}
 	}
 
+	/*
+	 * New rule: Prefer to small size instead of small align,
+	 * when we have align/size: 1M/1M, 2M/2M,
+	 *  min_align/size0: 1M/3M, max_align/size0_max: 2M/3M
+	 *  pick 1M/3M.
+	 * when we have align/size: 1M/1M, 64M/64M,
+	 *  min_align/size0: 32M/96M, max_align/size0_max: 64M/65M
+	 *  pick 64M/65M.
+	 * when we have align/size: 1M/1M, 16M/64M,
+	 *  min_align/size0: 8M/72M, max_align/size0_max: 16M/65M
+	 *  pick 16M/65M.
+	 * when we have align/size: 32M/64M, 128M/512M
+	 *  min_align/size0: 64M/576M, max_align/size0_max: 128M/576M
+	 *  pick 64M/576M.
+	 * when we have align/size: 16M/32M, 128M/512M
+	 *  min_align/size0: 64M/576M, max_align/size0_max: 128M/554M
+	 *  pick 128M/554M.
+	 * when we have align/size: 16M/64M
+	 *  min_align/size0: 8M/64M, max_align/size0_max: 16M/64M
+	 *  have to use 16M/64M.
+	 */
 	min_align = calculate_mem_align(aligns, max_order);
 	min_align = max(min_align, window_alignment(bus, b_res->flags));
+	max_align = max(max_align, window_alignment(bus, b_res->flags));
+	if (count == 1)
+		min_align = max_align;
+
 	size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align);
+	size0_max = calculate_memsize(size, min_size, 0, resource_size(b_res),
+					window_alignment(bus, b_res->flags));
+
+	if (size0_max < size0) {
+		size0 = size0_max;
+		min_align = max_align;
+		max_align--; /* to use small align for size1 calculation */
+	}
+
 	if (children_add_size > add_size)
 		add_size = children_add_size;
 	size1 = (!realloc_head || (realloc_head && !add_size)) ? size0 :
 		calculate_memsize(size, min_size, add_size,
-				resource_size(b_res), min_align);
+				resource_size(b_res),
+				min_align <= max_align ? min_align :
+					window_alignment(bus, b_res->flags));
 	if (!size0 && !size1) {
 		if (b_res->start || b_res->end)
 			dev_info(&bus->self->dev, "disabling bridge window %pR to %pR (unused)\n",