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Date:   Sat, 28 Mar 2020 08:18:27 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Marek Szyprowski <m.szyprowski@samsung.com>
Cc:     dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Alex Deucher <alexander.deucher@amd.com>,
        Shane Francis <bigbeeshane@gmail.com>,
        "Michael J . Ruhl" <michael.j.ruhl@intel.com>
Subject: Re: [PATCH v2] drm/prime: fix extracting of the DMA addresses from a
 scatterlist
Message-ID: <20200328071827.GA3648919@kroah.com>
References: <CGME20200327162330eucas1p1b0413e0e9887aa76d3048f86d2166dcd@eucas1p1.samsung.com>
 <20200327162126.29705-1-m.szyprowski@samsung.com>
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On Fri, Mar 27, 2020 at 05:21:26PM +0100, Marek Szyprowski wrote:
> Scatterlist elements contains both pages and DMA addresses, but one
> should not assume 1:1 relation between them. The sg->length is the size
> of the physical memory chunk described by the sg->page, while
> sg_dma_len(sg) is the size of the DMA (IO virtual) chunk described by
> the sg_dma_address(sg).
> 
> The proper way of extracting both: pages and DMA addresses of the whole
> buffer described by a scatterlist it to iterate independently over the
> sg->pages/sg->length and sg_dma_address(sg)/sg_dma_len(sg) entries.
> 
> Fixes: 42e67b479eab ("drm/prime: use dma length macro when mapping sg")
> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
> ---
>  drivers/gpu/drm/drm_prime.c | 37 +++++++++++++++++++++++++------------
>  1 file changed, 25 insertions(+), 12 deletions(-)

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>