From: Leon Romanovsky <leon@kernel.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: Doug Ledford <dledford@redhat.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Adit Ranadive <aditr@vmware.com>,
Ariel Elior <aelior@marvell.com>,
Bernard Metzler <bmt@zurich.ibm.com>,
Christian Benvenuti <benve@cisco.com>,
Dennis Dalessandro <dennis.dalessandro@intel.com>,
Devesh Sharma <devesh.sharma@broadcom.com>,
Faisal Latif <faisal.latif@intel.com>,
Gal Pressman <galpress@amazon.com>, Lijun Ou <oulijun@huawei.com>,
linux-rdma@vger.kernel.org,
Michal Kalderon <mkalderon@marvell.com>,
Mike Marciniszyn <mike.marciniszyn@intel.com>,
Naresh Kumar PBS <nareshkumar.pbs@broadcom.com>,
Nelson Escobar <neescoba@cisco.com>,
Parav Pandit <parav@nvidia.com>,
Parvi Kaustubhi <pkaustub@cisco.com>,
Potnuri Bharat Teja <bharat@chelsio.com>,
Selvin Xavier <selvin.xavier@broadcom.com>,
Shiraz Saleem <shiraz.saleem@intel.com>,
Somnath Kotur <somnath.kotur@broadcom.com>,
Sriharsha Basavapatna <sriharsha.basavapatna@broadcom.com>,
VMware PV-Drivers <pv-drivers@vmware.com>,
Weihang Li <liweihang@huawei.com>,
"Wei Hu(Xavier)" <huwei87@hisilicon.com>,
Yishai Hadas <yishaih@nvidia.com>,
Zhu Yanjun <yanjunz@nvidia.com>
Subject: Re: [PATCH rdma-next] RDMA: Explicitly pass in the dma_device to ib_register_device
Date: Wed, 23 Sep 2020 09:45:52 +0300 [thread overview]
Message-ID: <20200923064552.GG1223944@unreal> (raw)
In-Reply-To: <20200923053840.GA4809@infradead.org>
On Wed, Sep 23, 2020 at 06:38:40AM +0100, Christoph Hellwig wrote:
> > +static void setup_dma_device(struct ib_device *device,
> > + struct device *dma_device)
> > {
> > + if (!dma_device) {
> > /*
> > + * If the caller does not provide a DMA capable device then the
> > + * IB device will be used. In this case the caller should fully
> > + * setup the ibdev for DMA. This usually means using
> > + * dma_virt_ops.
> > */
> > +#ifdef CONFIG_DMA_OPS
> > + if (WARN_ON(!device->dev.dma_ops))
> > + return;
> > +#endif
>
> dma ops are entirely optiona and NULL for the most common case
> (direct mapping without an IOMMU).
IMHO we don't support such mode (without IOMMU).
>
> > + if (WARN_ON(!device->dev.dma_parms))
> > + return;
> > +
> > + dma_device = &device->dev;
> > + } else {
> > + device->dev.dma_parms = dma_device->dma_parms;
> > /*
> > + * Auto setup the segment size if a DMA device was passed in.
> > + * The PCI core sets the maximum segment size to 64 KB. Increase
> > + * this parameter to 2 GB.
> > */
> > + dma_set_max_seg_size(dma_device, SZ_2G);
>
> You can't just inherity DMA properties like this this. Please
> fix all code that looks at the seg size to look at the DMA device.
>
> Btw, where does the magic 2G come from?
It comes from patch d10bcf947a3e ("RDMA/umem: Combine contiguous
PAGE_SIZE regions in SGEs"), I can't say about all devices, but this is
the limit for mlx5, rxe and SIW devices.
Thanks
next prev parent reply other threads:[~2020-09-23 6:45 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-22 8:27 [PATCH rdma-next] RDMA: Explicitly pass in the dma_device to ib_register_device Leon Romanovsky
2020-09-22 8:58 ` Bernard Metzler
2020-09-22 10:14 ` Leon Romanovsky
2020-09-22 14:22 ` Bernard Metzler
2020-09-22 16:22 ` Jason Gunthorpe
2020-09-23 5:39 ` Christoph Hellwig
2020-09-23 18:35 ` Jason Gunthorpe
2020-09-24 5:53 ` Christoph Hellwig
2020-09-24 6:13 ` Christoph Hellwig
2020-09-24 11:55 ` Jason Gunthorpe
2020-09-24 7:31 ` Parav Pandit
2020-09-23 5:38 ` Christoph Hellwig
2020-09-23 6:45 ` Leon Romanovsky [this message]
2020-09-23 6:54 ` Christoph Hellwig
2020-09-23 7:10 ` Leon Romanovsky
2020-09-23 7:21 ` Christoph Hellwig
2020-09-23 18:34 ` Jason Gunthorpe
2020-09-24 5:49 ` Christoph Hellwig
2020-09-24 11:49 ` Jason Gunthorpe
2020-10-06 14:29 ` Bart Van Assche
2020-10-06 16:53 ` Jason Gunthorpe
2020-10-06 18:22 ` Bart Van Assche
2020-10-06 18:39 ` Jason Gunthorpe
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=20200923064552.GG1223944@unreal \
--to=leon@kernel.org \
--cc=aditr@vmware.com \
--cc=aelior@marvell.com \
--cc=benve@cisco.com \
--cc=bharat@chelsio.com \
--cc=bmt@zurich.ibm.com \
--cc=dennis.dalessandro@intel.com \
--cc=devesh.sharma@broadcom.com \
--cc=dledford@redhat.com \
--cc=faisal.latif@intel.com \
--cc=galpress@amazon.com \
--cc=hch@infradead.org \
--cc=huwei87@hisilicon.com \
--cc=jgg@nvidia.com \
--cc=linux-rdma@vger.kernel.org \
--cc=liweihang@huawei.com \
--cc=mike.marciniszyn@intel.com \
--cc=mkalderon@marvell.com \
--cc=nareshkumar.pbs@broadcom.com \
--cc=neescoba@cisco.com \
--cc=oulijun@huawei.com \
--cc=parav@nvidia.com \
--cc=pkaustub@cisco.com \
--cc=pv-drivers@vmware.com \
--cc=selvin.xavier@broadcom.com \
--cc=shiraz.saleem@intel.com \
--cc=somnath.kotur@broadcom.com \
--cc=sriharsha.basavapatna@broadcom.com \
--cc=yanjunz@nvidia.com \
--cc=yishaih@nvidia.com \
/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).