On 07/27/2015 06:27 PM, Bjorn Helgaas wrote:
Hi Don,
On Mon, Jul 27, 2015 at 10:00:53AM -0400, Don Dutile wrote:
On 07/20/2015 08:15 PM, Bjorn Helgaas wrote:
Stop caching the Invalidate Queue Depth in struct pci_dev.
pci_ats_queue_depth() is typically called only once per device, and it
returns a fixed value per-device, so callers who need the value frequently
can cache it themselves.
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
---
drivers/pci/ats.c | 9 ++++-----
include/linux/pci.h | 1 -
2 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
index 67524a7..bdb1383 100644
--- a/drivers/pci/ats.c
+++ b/drivers/pci/ats.c
@@ -20,16 +20,12 @@
void pci_ats_init(struct pci_dev *dev)
{
int pos;
- u16 cap;
pos = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ATS);
if (!pos)
return;
dev->ats_cap = pos;
- pci_read_config_word(dev, dev->ats_cap + PCI_ATS_CAP, &cap);
- dev->ats_qdep = PCI_ATS_CAP_QDEP(cap) ? PCI_ATS_CAP_QDEP(cap) :
- PCI_ATS_MAX_QDEP;
}
/**
@@ -131,13 +127,16 @@ EXPORT_SYMBOL_GPL(pci_restore_ats_state);
*/
int pci_ats_queue_depth(struct pci_dev *dev)
{
+ u16 cap;
+
if (!dev->ats_cap)
return -EINVAL;
if (dev->is_virtfn)
return 0;
hmmm, isn't one of the fixes in this patch set to
change the caching of ats queue depth ? won't above
make it 0 for all VF's ? is that correct, or desired (virtual) value?
Per spec (SR-IOV r1.1., sec 3.7.4), the ATS queue depth register on a VF
always contains zero.
Here's the v4.1 code:
int pci_ats_queue_depth(struct pci_dev *dev)
{
if (dev->is_virtfn)
return 0;
if (dev->ats)
return dev->ats->qdep;
...
In v4.1, pci_ats_queue_depth() always returned 0 for a VF. For VFs, we
didn't look at the dev->ats->qdep cache. So I don't think this changes
anything for the caller.
A previous patch changed this path so we return -EINVAL instead of 0 for
VFs that don't support ATS. I think the previous behavior there was wrong,
but I doubt anybody noticed.
Bjorn
ok. thanks for the sanity check.
- return dev->ats_qdep;
+ pci_read_config_word(dev, dev->ats_cap + PCI_ATS_CAP, &cap);
+ return PCI_ATS_CAP_QDEP(cap) ? PCI_ATS_CAP_QDEP(cap) : PCI_ATS_MAX_QDEP;
}
EXPORT_SYMBOL_GPL(pci_ats_queue_depth);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 307f96a..4b484fd 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -378,7 +378,6 @@ struct pci_dev {
};
u16 ats_cap; /* ATS Capability offset */
u8 ats_stu; /* ATS Smallest Translation Unit */
- u8 ats_qdep; /* ATS Invalidate Queue Depth */
atomic_t ats_ref_cnt; /* number of VFs with ATS enabled */
#endif
phys_addr_t rom; /* Physical address of ROM if it's not from the BAR */
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