From: konrad.wilk@oracle•com (Konrad Rzeszutek Wilk)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions
Date: Fri, 8 Aug 2014 13:14:02 -0400 [thread overview]
Message-ID: <20140808171402.GF13551@laptop.dumpdata.com> (raw)
In-Reply-To: <53E3F538.8030000@codeaurora.org>
On Thu, Aug 07, 2014 at 02:52:56PM -0700, Olav Haugan wrote:
> On 8/6/2014 11:24 PM, Thierry Reding wrote:
> > On Wed, Aug 06, 2014 at 04:28:45PM -0700, Olav Haugan wrote:
> >> On 8/6/2014 1:17 PM, Joerg Roedel wrote:
> >>> On Wed, Aug 06, 2014 at 10:08:55AM -0700, Olav Haugan wrote:
> >>>> so you are suggesting that I check in "bus_set_iommu()" whether the
> >>>> driver has set the map_sg/unmap_sg function pointers or not and if not
> >>>> set it to the default? Is bus_set_iommu() the only way drivers can set
> >>>> up the callbacks?
> >>>
> >>> This doesn't work as the iommu_ops are now const. You have to either
> >>> update the iommu drivers individually to point to the default function,
> >>> or you do the check in the API function itself and fall back to the
> >>> default it no call-back is provided.
> >>>
> >>
> >> Ok, then I think it is better to just leave the fallback where it is now
> >> in the function itself.
> >
> > What Konrad was suggesting is what I also proposed. The idea is to
> > implement a fallback as standalone function, then make all drivers use
> > that by default in the struct iommu_ops that they register. When drivers
> > implement an optimized version they can simply replace the fallback
> > implementation with their own.
> >
>
> Ok, I can do that. I misunderstood the point of the fallback. I thought
> the point of the fallback was to catch drivers that forget/neglect to
> implement this callback. If that is not a concern I will update my patch
Nah. We want those drivers to crash and burn so we can see that and
fix it. And by fix I meant it would just point do:
.map_sg = generic_map_sg,
.unmap_sg = generic_unmap_sg,
In other words, none of the function ops will have an NULL functions.
> to create a separate function that I will point all existing drivers to.
Excellent!
>
> Thanks,
>
> Olav
>
> --
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
prev parent reply other threads:[~2014-08-08 17:14 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-01 0:54 [PATCH v4 0/1] Add iommu map_sg/unmap_sg API Olav Haugan
2014-08-01 0:54 ` [PATCH v4 1/1] iommu-api: Add map_sg/unmap_sg functions Olav Haugan
2014-08-01 8:22 ` Will Deacon
2014-08-01 16:44 ` Olav Haugan
2014-08-04 18:03 ` Olav Haugan
2014-08-05 15:13 ` Konrad Rzeszutek Wilk
2014-08-06 17:08 ` Olav Haugan
2014-08-06 20:17 ` Joerg Roedel
2014-08-06 23:28 ` Olav Haugan
2014-08-07 6:24 ` Thierry Reding
2014-08-07 21:52 ` Olav Haugan
2014-08-08 17:14 ` Konrad Rzeszutek Wilk [this message]
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