Messages in this thread | | | Date | Mon, 7 Oct 2013 20:38:45 +0200 | From | Alexander Gordeev <> | Subject | Re: [PATCH RFC 54/77] ntb: Ensure number of MSIs on SNB is enough for the link interrupt |
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On Mon, Oct 07, 2013 at 09:50:57AM -0700, Jon Mason wrote: > On Sat, Oct 05, 2013 at 11:43:04PM +0200, Alexander Gordeev wrote: > > On Wed, Oct 02, 2013 at 05:48:05PM -0700, Jon Mason wrote: > > > On Wed, Oct 02, 2013 at 12:49:10PM +0200, Alexander Gordeev wrote: > > > > Signed-off-by: Alexander Gordeev <agordeev@redhat.com> > > > > --- > > > > drivers/ntb/ntb_hw.c | 2 +- > > > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > > > > > diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c > > > > index de2062c..eccd5e5 100644 > > > > --- a/drivers/ntb/ntb_hw.c > > > > +++ b/drivers/ntb/ntb_hw.c > > > > @@ -1066,7 +1066,7 @@ static int ntb_setup_msix(struct ntb_device *ndev) > > > > /* On SNB, the link interrupt is always tied to 4th vector. If > > > > * we can't get all 4, then we can't use MSI-X. > > > > */ > > > > - if (ndev->hw_type != BWD_HW) { > > > > + if ((rc < SNB_MSIX_CNT) && (ndev->hw_type != BWD_HW)) { > > > > > > Nack, this check is unnecessary. > > > > If SNB can do more than SNB_MSIX_CNT MSI-Xs then this check is needed > > to enable less than maximum MSI-Xs in case the maximum was not allocated. > > Otherwise SNB will fallback to single MSI instead of multiple MSI-Xs. > > Per the comment in the code snippet above, "If we can't get all 4, > then we can't use MSI-X". There is already a check to see if more > than 4 were acquired. So it's not possible to hit this. Even if it > was, don't use SNB_MSIX_CNT here (limits.msix_cnt is the preferred > variable). Also, the "()" are unnecessary.
The changelog is definitely bogus. I meant here an improvement to the existing scheme, not a conversion to the new one:
msix_entries = msix_table_size(val);
Getting i.e. 16 vectors here.
if (msix_entries > ndev->limits.msix_cnt) { rc = -EINVAL; goto err; }
Upper limit check i.e. succeeds.
[...]
rc = pci_enable_msix(pdev, ndev->msix_entries, msix_entries);
pci_enable_msix() does not success and returns i.e. 8 here, should retry.
if (rc < 0) goto err1; if (rc > 0) { /* On SNB, the link interrupt is always tied to 4th vector. If * we can't get all 4, then we can't use MSI-X. */ if (ndev->hw_type != BWD_HW) {
On SNB bail out here, although could have continue with 8 vectors. Can only use SNB_MSIX_CNT here, since limits.msix_cnt is the upper limit.
rc = -EIO; goto err1; }
[...] }
-- Regards, Alexander Gordeev agordeev@redhat.com
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