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From:   Tom Murphy <murphyt7@tcd.ie>
Date:   Tue, 8 Sep 2020 23:43:19 +0100
Message-ID: <CALQxJut5c=cWdi+SVkN3JnbkhPSYmLkOyRUhduL-UJ9gyKn9Ow@mail.gmail.com>
Subject: Re: [Intel-gfx] [PATCH 0/8] Convert the intel iommu driver to the
 dma-iommu api
To:     Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc:     Logan Gunthorpe <logang@deltatee.com>, kvm@vger.kernel.org,
        David Airlie <airlied@linux.ie>,
        dri-devel@lists.freedesktop.org,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        linux-tegra@vger.kernel.org, Julien Grall <julien.grall@arm.com>,
        Will Deacon <will@kernel.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        linux-samsung-soc@vger.kernel.org, Marc Zyngier <maz@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        linux-rockchip@lists.infradead.org, Andy Gross <agross@kernel.org>,
        linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, intel-gfx@lists.freedesktop.org,
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        Robin Murphy <robin.murphy@arm.com>
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On Tue, 8 Sep 2020 at 16:56, Tvrtko Ursulin
<tvrtko.ursulin@linux.intel.com> wrote:
>
>
> On 08/09/2020 16:44, Logan Gunthorpe wrote:
> > On 2020-09-08 9:28 a.m., Tvrtko Ursulin wrote:
> >>>
> >>> diff --git a/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> b/drivers/gpu/drm/i915/i915
> >>> index b7b59328cb76..9367ac801f0c 100644
> >>> --- a/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> +++ b/drivers/gpu/drm/i915/i915_scatterlist.h
> >>> @@ -27,13 +27,19 @@ static __always_inline struct sgt_iter {
> >>>    } __sgt_iter(struct scatterlist *sgl, bool dma) {
> >>>           struct sgt_iter s = { .sgp = sgl };
> >>>
> >>> +       if (sgl && !sg_dma_len(s.sgp))
> >>
> >> I'd extend the condition to be, just to be safe:
> >>      if (dma && sgl && !sg_dma_len(s.sgp))
> >>
> >
> > Right, good catch, that's definitely necessary.
> >
> >>> +               s.sgp = NULL;
> >>> +
> >>>           if (s.sgp) {
> >>>                   s.max = s.curr = s.sgp->offset;
> >>> -               s.max += s.sgp->length;
> >>> -               if (dma)
> >>> +
> >>> +               if (dma) {
> >>> +                       s.max += sg_dma_len(s.sgp);
> >>>                           s.dma = sg_dma_address(s.sgp);
> >>> -               else
> >>> +               } else {
> >>> +                       s.max += s.sgp->length;
> >>>                           s.pfn = page_to_pfn(sg_page(s.sgp));
> >>> +               }
> >>
> >> Otherwise has this been tested or alternatively how to test it? (How to
> >> repro the issue.)
> >
> > It has not been tested. To test it, you need Tom's patch set without the
> > last "DO NOT MERGE" patch:
> >
> > https://lkml.kernel.org/lkml/20200907070035.GA25114@infradead.org/T/
>
> Tom, do you have a branch somewhere I could pull from? (Just being lazy
> about downloading a bunch of messages from the archives.)

I don't unfortunately. I'm working locally with poor internet.

>
> What GPU is in your Lenovo x1 carbon 5th generation and what
> graphical/desktop setup I need to repro?


Is this enough info?:

$ lspci -vnn | grep VGA -A 12
00:02.0 VGA compatible controller [0300]: Intel Corporation HD
Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA controller])
    Subsystem: Lenovo ThinkPad X1 Carbon 5th Gen [17aa:224f]
    Flags: bus master, fast devsel, latency 0, IRQ 148
    Memory at eb000000 (64-bit, non-prefetchable) [size=16M]
    Memory at 60000000 (64-bit, prefetchable) [size=256M]
    I/O ports at e000 [size=64]
    [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
    Capabilities: [40] Vendor Specific Information: Len=0c <?>
    Capabilities: [70] Express Root Complex Integrated Endpoint, MSI 00
    Capabilities: [ac] MSI: Enable+ Count=1/1 Maskable- 64bit-
    Capabilities: [d0] Power Management version 2
    Capabilities: [100] Process Address Space ID (PASID)
    Capabilities: [200] Address Translation Service (ATS)


>
> Regards,
>
> Tvrtko