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Mon, 7 Sep 2020 14:02:17 +0000 (GMT) Subject: Re: [PATCH v10 30/30] videobuf2: use sgtable-based scatterlist wrappers To: Tomasz Figa Cc: dri-devel , "list@263.net:IOMMU DRIVERS" , Joerg Roedel , iommu@lists.linux-foundation.org, linaro-mm-sig@lists.linaro.org, Linux Kernel Mailing List , Christoph Hellwig , Robin Murphy , Bartlomiej Zolnierkiewicz , "list@263.net:IOMMU DRIVERS" , Joerg Roedel , linux-arm-kernel@lists.infradead.org, David Airlie , Daniel Vetter , Mauro Carvalho Chehab , Linux Media Mailing List From: Marek Szyprowski Message-ID: Date: Mon, 7 Sep 2020 16:02:17 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Transfer-Encoding: 7bit Content-Language: en-US X-Brightmail-Tracker: H4sIAAAAAAAAA02SWUwTURSGvbMxEEuGoukJGjGN0WgUBFwmAUWJy+iDokYfNFirjCyy2QEV eLAuoBTUilGwECSKIosCZVEQFyBQKaFRIApq3KgRjQRiKQFtqLQjytt3zvn/e/6TXBqXWkkv OioukVfFKWPklBtR1zZuWha9Zo9iuf55EHvB1I6xVbkVJGuvu4yzPdYhii0pa8XYwqeBbEZe pQs70vMJY/X9r0i2uyGfYrMqa0n2jt6GsU3DZpK1pE1Q69w5c1MBxpUXlCMuT/2S4B6PFhKc vjSD4h6MfiS5D5kGjKsuOsm9nejHuSu9xYh71KemuIs1pYiz6OeFSva6BYXzMVHHeJXv2gNu kelffqGEhkUnitKKMDV6NleDXGlgVkDVqXpKg9xoKXMXgba24m8xgsCmHcPEwoLgmrWMmrJk tZwjxEExgt5zH0jHQMoMIagZ3+RgT2YnvB4qdhpmMQvgd3uu81mcaSPB+LHPaaAYP9AMapwi CbMWjPffEw4mJg1jY/24g2cz+6HN+JkQNR7Qft3sZFdmB+gsRszBOOMNDwbzcZFl8MZ8wxkb mKs0FKXVkmLsDVBeUoaL7AnfDTUuIs8Fe/2U4QyCT6Z7LmKRhaD7dC4SVYHwzvRrMio9uWIx VDT4iu310GnsQY42MO7QO+ghhnCH7LocXGxL4Hy6VFQvBJ3h/r+1TS+6cC2S66adppt2jm7a Obr/ewsRUYpkfJIQG8ELfnH8cR9BGSskxUX4HIqP1aPJz9gxYfj5EFm7DjYjhkbymZIB2W6F lFQeE5JjmxHQuHyWJKSzY79UEq5MTuFV8QpVUgwvNKM5NCGXSQJufguTMhHKRP4Izyfwqqkp Rrt6qZE22oCC99be6V4pUzU84c42lnMtKcTGWxGDjcGl4buGbSXafT+2y1Zva2xWZG9ITm3K 9s681KcSFluidKE3O3mNzWPIHrB0/pWtRv/uVpPZVllvO1rfSN4OM467jKszwVW+ShHon28P GdhsC/+6JT6VmJFtDTh9uDrHnrq1OFROCJFKvyW4SlD+AbP5khyIAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmpnleLIzCtJLcpLzFFi42I5/e/4Xd0s27B4gz0T5C16z51kstg4Yz2r xf9tE5ktrnx9z2axcvVRJosF+60tOmdvYLf4cuUhk8Wmx9dYLS7vmsNm0bNhK6vFsk1/mCwO fnjCavG59R+bA5/Hk4PzmDzWzFvD6DG74SKLx95vC1g8Nq3qZPPY/u0Bq8f97uNMHpuX1Hvc /veY2WPyjeWMHrtvNrB59G1ZxejxeZNcAG+Unk1RfmlJqkJGfnGJrVK0oYWRnqGlhZ6RiaWe obF5rJWRqZK+nU1Kak5mWWqRvl2CXkbb01+MBbvUK5a0LmFqYDwg08XIySEhYCLRc7idpYuR i0NIYCmjxMmJV5ggEjISJ6c1sELYwhJ/rnWxQRS9ZZR4dLIbrEhYIEji+vvlbCC2iICKxO+T M8BsZoFTrBITfztCNPQySfSdvQM2iU3AUKLrbRdYEa+AncSpdfdYQGwWoOYfPx4zg9iiAnES Z3peQNUISpyc+QSshlMgUGLW51NMEAvMJOZtfsgMYctLbH87B8oWl7j1ZD7TBEahWUjaZyFp mYWkZRaSlgWMLKsYRVJLi3PTc4sN9YoTc4tL89L1kvNzNzECE8G2Yz8372C8tDH4EKMAB6MS D+8L8dB4IdbEsuLK3EOMEhzMSiK8TmdPxwnxpiRWVqUW5ccXleakFh9iNAV6biKzlGhyPjBJ 5ZXEG5oamltYGpobmxubWSiJ83YIHIwREkhPLEnNTk0tSC2C6WPi4JRqYOR98ancUa3b2nL6 pZrYzd8LNA2D/CobZaZWb+1e0jF7z6S7Un13n9oU/nmyf226kpqIo/DfeGeXHM2PjH2rsle4 Jx60mRJfxxqzStup6UHPnYPTjcq/i9QefrfnlkGVq/JLpk1u8usyF4UmTD+RUWMiwXdzkcmp G6GzKuLupwQK/V+47/jThUosxRmJhlrMRcWJAEFLwmMaAwAA X-CMS-MailID: 20200907140218eucas1p12759ab0e566e0438b407a2756a73e765 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-RootMTR: 20200904133512eucas1p204efa4e252ceb5fb50715239705f9965 X-EPHeader: CA CMS-TYPE: 201P X-CMS-RootMailID: 20200904133512eucas1p204efa4e252ceb5fb50715239705f9965 References: <20200904131711.12950-1-m.szyprowski@samsung.com> <20200904131711.12950-31-m.szyprowski@samsung.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Tomasz, On 07.09.2020 15:07, Tomasz Figa wrote: > On Fri, Sep 4, 2020 at 3:35 PM Marek Szyprowski > wrote: >> Use recently introduced common wrappers operating directly on the struct >> sg_table objects and scatterlist page iterators to make the code a bit >> more compact, robust, easier to follow and copy/paste safe. >> >> No functional change, because the code already properly did all the >> scatterlist related calls. >> >> Signed-off-by: Marek Szyprowski >> Reviewed-by: Robin Murphy >> --- >> .../common/videobuf2/videobuf2-dma-contig.c | 34 ++++++++----------- >> .../media/common/videobuf2/videobuf2-dma-sg.c | 32 +++++++---------- >> .../common/videobuf2/videobuf2-vmalloc.c | 12 +++---- >> 3 files changed, 31 insertions(+), 47 deletions(-) >> > Thanks for the patch! Please see my comments inline. > >> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c >> index ec3446cc45b8..1b242d844dde 100644 >> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c >> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c >> @@ -58,10 +58,10 @@ static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt) >> unsigned int i; >> unsigned long size = 0; >> >> - for_each_sg(sgt->sgl, s, sgt->nents, i) { >> + for_each_sgtable_dma_sg(sgt, s, i) { >> if (sg_dma_address(s) != expected) >> break; >> - expected = sg_dma_address(s) + sg_dma_len(s); >> + expected += sg_dma_len(s); >> size += sg_dma_len(s); >> } >> return size; >> @@ -103,8 +103,7 @@ static void vb2_dc_prepare(void *buf_priv) >> if (!sgt) >> return; >> >> - dma_sync_sg_for_device(buf->dev, sgt->sgl, sgt->orig_nents, >> - buf->dma_dir); >> + dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir); >> } >> >> static void vb2_dc_finish(void *buf_priv) >> @@ -115,7 +114,7 @@ static void vb2_dc_finish(void *buf_priv) >> if (!sgt) >> return; >> >> - dma_sync_sg_for_cpu(buf->dev, sgt->sgl, sgt->orig_nents, buf->dma_dir); >> + dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir); >> } >> >> /*********************************************/ >> @@ -275,8 +274,8 @@ static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf, >> * memory locations do not require any explicit cache >> * maintenance prior or after being used by the device. >> */ >> - dma_unmap_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents, >> - attach->dma_dir, DMA_ATTR_SKIP_CPU_SYNC); >> + dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, >> + DMA_ATTR_SKIP_CPU_SYNC); >> sg_free_table(sgt); >> kfree(attach); >> db_attach->priv = NULL; >> @@ -301,8 +300,8 @@ static struct sg_table *vb2_dc_dmabuf_ops_map( >> >> /* release any previous cache */ >> if (attach->dma_dir != DMA_NONE) { >> - dma_unmap_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents, >> - attach->dma_dir, DMA_ATTR_SKIP_CPU_SYNC); >> + dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir, >> + DMA_ATTR_SKIP_CPU_SYNC); >> attach->dma_dir = DMA_NONE; >> } >> >> @@ -310,9 +309,8 @@ static struct sg_table *vb2_dc_dmabuf_ops_map( >> * mapping to the client with new direction, no cache sync >> * required see comment in vb2_dc_dmabuf_ops_detach() >> */ >> - sgt->nents = dma_map_sg_attrs(db_attach->dev, sgt->sgl, sgt->orig_nents, >> - dma_dir, DMA_ATTR_SKIP_CPU_SYNC); >> - if (!sgt->nents) { >> + if (dma_map_sgtable(db_attach->dev, sgt, dma_dir, >> + DMA_ATTR_SKIP_CPU_SYNC)) { >> pr_err("failed to map scatterlist\n"); >> mutex_unlock(lock); >> return ERR_PTR(-EIO); > As opposed to dma_map_sg_attrs(), dma_map_sgtable() now returns an > error code on its own. Is it expected to ignore it and return -EIO? Those errors are more or less propagated to userspace and -EIO has been already widely documented in V4L2 documentation as the error code for the most of the V4L2 ioctls. I don't want to change it. A possible -EINVAL returned from dma_map_sgtable() was just one of the 'generic' error codes, not very descriptive in that case. Probably the main problem here is that dma_map_sg() and friend doesn't return any error codes... > ... Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland