Re: crypto/cavium MSI-X fixups

From	David Daney <ddaney.cavm@gmail.com>
Newsgroups	linux.kernel
Subject	Re: crypto/cavium MSI-X fixups
Date	2017-02-22 18:50 +0100
Message-ID	<tdJd8-5hl-7@gated-at.bofh.it> (permalink)
References	<tb22C-54i-3@gated-at.bofh.it> <tcDCO-1MT-33@gated-at.bofh.it> <tcDCO-1MT-31@gated-at.bofh.it> <tdzx8-6xa-25@gated-at.bofh.it> <tdzx8-6xa-23@gated-at.bofh.it>
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On 02/21/2017 11:27 PM, Christoph Hellwig wrote:
> On Tue, Feb 21, 2017 at 09:36:04AM -0800, David Daney wrote:
>> With respect to pci_enable_msix(), what do you recommend as a replacement?
>
> pci_alloc_irq_vectors.  In fact I have a tree ready for after -rc1
> that removes pci_enable_msix() entirely.

I would like to see something that handles the case of this driver that 
I am attempting to get merged:


https://lkml.org/lkml/2017/2/15/1209


>
>> For the crypto/cavium driver, you recommend pci_alloc_irq_vectors(), which
>> works well if the required MSI-X indexes are contiguous starting at zero.
>> What would be used for a device that has 184 MSI-X, but only a sparse
>> subset (fewer than half) of these are required for the driver operation.
>> It would waste system resources to use an API that forces us to allocate
>> 184 when only 80 are required.
>
> Currently we don't have a good API for that.  I've not been through all
> users of pci_enable_msix_{range,exact} yet, but so far I've only found
> one user not using all vectors from 0 to some limit.  Depending how many
> such users we have and how they'll look I will have to look into an API
> to support that use case.
>

See the patch above for the case that doesn't use 0..UPPER_LIMIT

David Daney

Thread

crypto/cavium MSI-X fixups Christoph Hellwig <hch@lst.de> - 2017-02-15 08:20 +0100
  [PATCH 3/3] crypto: cavium/cptvf: switch to pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2017-02-15 08:20 +0100
  [PATCH 2/3] crypto: cavium/cptpf: switch to pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2017-02-15 08:20 +0100
  [PATCH 1/3] crypto: cavium: remove dead MSI-X related define Christoph Hellwig <hch@lst.de> - 2017-02-15 08:20 +0100
  Re: crypto/cavium MSI-X fixups Christoph Hellwig <hch@lst.de> - 2017-02-19 18:40 +0100
    Re: crypto/cavium MSI-X fixups Christoph Hellwig <hch@lst.de> - 2017-02-22 08:30 +0100
      Re: crypto/cavium MSI-X fixups David Daney <ddaney.cavm@gmail.com> - 2017-02-22 18:50 +0100
  Re: crypto/cavium MSI-X fixups Herbert Xu <herbert@gondor.apana.org.au> - 2017-02-23 13:20 +0100

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