From: Liviu Dudau <Liviu.Dudau@arm.com>
To: Brian Starkey <brian.starkey@arm.com>
Cc: Mali DP Maintainers <malidp@foss.arm.com>,
Daniel Vetter <daniel.vetter@intel.com>,
David Airlie <airlied@linux.ie>,
DRI-devel <dri-devel@lists.freedesktop.org>,
LKML <linux-kernel@vger.kernel.org>,
Jani Nikula <jani.nikula@linux.intel.com>,
Sean Paul <seanpaul@chromium.org>,
Liviu Dudau <liviu.dudau@arm.com>
Subject: [PATCH] drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1
Date: Wed, 1 Nov 2017 14:14:19 +0000 [thread overview]
Message-ID: <20171101141419.3180-1-Liviu.Dudau@arm.com> (raw)
drm_gem_cma_prime_import_sg_table() will fail if the number of entries
in the sg_table > 1. However, you can have a device that uses an IOMMU
engine and can map a discontiguous buffer with multiple entries that
have consecutive sg_dma_addresses, effectively making it contiguous.
Allow for that scenario by testing the entries in the sg_table for
contiguous coverage.
Reviewed-by: Brian Starkey <brian.starkey@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
---
Hi,
This patch is the only change I need in order to be able to use existing
IOMMU domain infrastructure with the Mali DP driver. I have tested the
patch and I know it works correctly for my setup, but I would like to get
some comments on whether I am on the right path or if CMA really wants to
see an sg_table with only one entry.
Best regards,
Liviu
drivers/gpu/drm/drm_gem_cma_helper.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 020e7668dfaba..43b179212052d 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -482,8 +482,26 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
{
struct drm_gem_cma_object *cma_obj;
- if (sgt->nents != 1)
- return ERR_PTR(-EINVAL);
+ if (sgt->nents != 1) {
+ /* check if the entries in the sg_table are contiguous */
+ dma_addr_t next_addr = sg_dma_address(sgt->sgl);
+ struct scatterlist *s;
+ unsigned int i;
+
+ for_each_sg(sgt->sgl, s, sgt->nents, i) {
+ /*
+ * sg_dma_address(s) is only valid for entries
+ * that have sg_dma_len(s) != 0
+ */
+ if (!sg_dma_len(s))
+ continue;
+
+ if (sg_dma_address(s) != next_addr)
+ return ERR_PTR(-EINVAL);
+
+ next_addr = sg_dma_address(s) + sg_dma_len(s);
+ }
+ }
/* Create a CMA GEM buffer. */
cma_obj = __drm_gem_cma_create(dev, attach->dmabuf->size);
--
2.14.3
next reply other threads:[~2017-11-01 14:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-01 14:14 Liviu Dudau [this message]
2017-11-10 4:26 ` [PATCH] drm: gem_cma_helper.c: Allow importing of contiguous scatterlists with nents > 1 Laurent Pinchart
2017-11-10 13:33 ` [PATCH v2] " Liviu Dudau
2017-11-11 12:47 ` Laurent Pinchart
2017-11-15 13:04 ` Liviu Dudau
2017-11-15 14:24 ` Noralf Trønnes
2017-11-15 14:41 ` Liviu Dudau
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171101141419.3180-1-Liviu.Dudau@arm.com \
--to=liviu.dudau@arm.com \
--cc=airlied@linux.ie \
--cc=brian.starkey@arm.com \
--cc=daniel.vetter@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=jani.nikula@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=malidp@foss.arm.com \
--cc=seanpaul@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).