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powerpc/powernv: replace the hard coded boundary with gate

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At the moment 64bit-prefetchable window can be maximum 64GB, which is
currently got from device tree. This means that in shared mode the maximum
supported VF BAR size is 64GB/256=256MB. While this size could exhaust the
whole 64bit-prefetchable window. This is a design decision to set a
boundary to 64MB of the VF BAR size. Since VF BAR size with 64MB would
occupy a quarter of the 64bit-prefetchable window, this is affordable.

This patch replaces magic limit of 64MB with "gate", which is 1/4 of the
M64 Segment Size(m64_segsize >> 2) and adds comment to explain the reason
for it.

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Reviewed-by: Gavin Shan <gwshan@linux.vent.ibm.com>
Acked-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Wei Yang 2015-10-22 09:22:17 +08:00 committed by Michael Ellerman
parent ee8222fe95
commit f2dd0afeea
1 changed files with 19 additions and 9 deletions
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28
arch/powerpc/platforms/powernv/pci-ioda.c
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@ -2798,8 +2798,9 @@ static void pnv_pci_init_ioda_msis(struct pnv_phb *phb) { }
#ifdef CONFIG_PCI_IOV
static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
{
struct pci_controller *hose;
struct pnv_phb *phb;
struct pci_controller *hose = pci_bus_to_host(pdev->bus);
struct pnv_phb *phb = hose->private_data;
const resource_size_t gate = phb->ioda.m64_segsize >> 2;
struct resource *res;
int i;
resource_size_t size;
@ -2809,9 +2810,6 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
if (!pdev->is_physfn || pdev->is_added)
return;
hose = pci_bus_to_host(pdev->bus);
phb = hose->private_data;
pdn = pci_get_pdn(pdev);
pdn->vfs_expanded = 0;
pdn->m64_single_mode = false;
@ -2832,10 +2830,22 @@ static void pnv_pci_ioda_fixup_iov_resources(struct pci_dev *pdev)
size = pci_iov_resource_size(pdev, i + PCI_IOV_RESOURCES);
/* bigger than 64M */
if (size > (1 << 26)) {
dev_info(&pdev->dev, "PowerNV: VF BAR%d: %pR IOV size is bigger than 64M, roundup power2\n",
i, res);
/*
* If bigger than quarter of M64 segment size, just round up
* power of two.
*
* Generally, one M64 BAR maps one IOV BAR. To avoid conflict
* with other devices, IOV BAR size is expanded to be
* (total_pe * VF_BAR_size). When VF_BAR_size is half of M64
* segment size , the expanded size would equal to half of the
* whole M64 space size, which will exhaust the M64 Space and
* limit the system flexibility. This is a design decision to
* set the boundary to quarter of the M64 segment size.
*/
if (size > gate) {
dev_info(&pdev->dev, "PowerNV: VF BAR%d: %pR IOV size "
"is bigger than %lld, roundup power2\n",
i, res, gate);
mul = roundup_pow_of_two(total_vfs);
pdn->m64_single_mode = true;
break;