Re: [PATCH 02/13] drm/exynos: Use FOLL_LONGTERM for g2d cmdlists

From: John Hubbard
Date: Wed Oct 07 2020 - 16:43:24 EST


On 10/7/20 9:44 AM, Daniel Vetter wrote:
The exynos g2d interface is very unusual, but it looks like the
userptr objects are persistent. Hence they need FOLL_LONGTERM.

Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxx>
Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
Cc: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx>
Cc: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>
Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Cc: Kukjin Kim <kgene@xxxxxxxxxx>
Cc: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: Jérôme Glisse <jglisse@xxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: linux-mm@xxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-samsung-soc@xxxxxxxxxxxxxxx
Cc: linux-media@xxxxxxxxxxxxxxx
---
drivers/gpu/drm/exynos/exynos_drm_g2d.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_g2d.c b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
index c83f6faac9de..514fd000feb1 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_g2d.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_g2d.c
@@ -478,7 +478,8 @@ static dma_addr_t *g2d_userptr_get_dma_addr(struct g2d_data *g2d,
goto err_free;
}
- ret = pin_user_pages_fast(start, npages, FOLL_FORCE | FOLL_WRITE,
+ ret = pin_user_pages_fast(start, npages,
+ FOLL_FORCE | FOLL_WRITE | FOLL_LONGTERM,
g2d_userptr->pages);
if (ret != npages) {
DRM_DEV_ERROR(g2d->dev,


Looks good from a pin_user_pages_fast() point of view. I'm of course not a exynos
developer, so we still need a look from one of those, ideally, but:

Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>

thanks,
--
John Hubbard
NVIDIA