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From:   "Ruhl, Michael J" <michael.j.ruhl@intel.com>
To:     Shane Francis <bigbeeshane@gmail.com>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>
CC:     "airlied@linux.ie" <airlied@linux.ie>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "amd-gfx-request@lists.freedesktop.org" 
        <amd-gfx-request@lists.freedesktop.org>,
        "alexander.deucher@amd.com" <alexander.deucher@amd.com>,
        "christian.koenig@amd.com" <christian.koenig@amd.com>
Subject: RE: [PATCH v4 3/3] drm/radeon: fix scatter-gather mapping with user
 pages
Thread-Topic: [PATCH v4 3/3] drm/radeon: fix scatter-gather mapping with
 user pages
Thread-Index: AQHWAoUBcNgIkBIx5kKMIMnKtZMniKhZW20g
Date:   Wed, 25 Mar 2020 14:19:48 +0000
Message-ID: <14063C7AD467DE4B82DEDB5C278E8663FFFBD48B@fmsmsx107.amr.corp.intel.com>
References: <20200325090741.21957-1-bigbeeshane@gmail.com>
 <20200325090741.21957-4-bigbeeshane@gmail.com>
In-Reply-To: <20200325090741.21957-4-bigbeeshane@gmail.com>
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>-----Original Message-----
>From: dri-devel <dri-devel-bounces@lists.freedesktop.org> On Behalf Of
>Shane Francis
>Sent: Wednesday, March 25, 2020 5:08 AM
>To: dri-devel@lists.freedesktop.org
>Cc: airlied@linux.ie; linux-kernel@vger.kernel.org; bigbeeshane@gmail.com;
>amd-gfx-request@lists.freedesktop.org; alexander.deucher@amd.com;
>christian.koenig@amd.com
>Subject: [PATCH v4 3/3] drm/radeon: fix scatter-gather mapping with user
>pages
>
>Calls to dma_map_sg may return segments / entries than requested

"may return less segment..." ?
                       ^^^

>if they fall on page bounderies. The old implementation did not
>support this use case.
>
>Signed-off-by: Shane Francis <bigbeeshane@gmail.com>
>---
> drivers/gpu/drm/radeon/radeon_ttm.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c
>b/drivers/gpu/drm/radeon/radeon_ttm.c
>index 3b92311d30b9..b3380ffab4c2 100644
>--- a/drivers/gpu/drm/radeon/radeon_ttm.c
>+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
>@@ -528,7 +528,7 @@ static int radeon_ttm_tt_pin_userptr(struct ttm_tt
>*ttm)
>
> 	r = -ENOMEM;
> 	nents = dma_map_sg(rdev->dev, ttm->sg->sgl, ttm->sg->nents,
>direction);
>-	if (nents != ttm->sg->nents)
>+	if (nents == 0)
> 		goto release_sg;

This looks correct to me.

Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>

M
> 	drm_prime_sg_to_page_addr_arrays(ttm->sg, ttm->pages,
>--
>2.26.0
>
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