From: Ira Weiny <ira.weiny@intel.com>
To: Ben Widawsky <ben.widawsky@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org,
linux-pci@vger.kernel.org
Subject: Re: [PATCH V6 06/10] cxl/pci: Find the DOE mailbox which supports CDAT
Date: Tue, 1 Feb 2022 14:18:41 -0800 [thread overview]
Message-ID: <20220201221841.GO785175@iweiny-DESK2.sc.intel.com> (raw)
In-Reply-To: <20220201184947.5yx4l74nruyoapvr@intel.com>
On Tue, Feb 01, 2022 at 10:49:47AM -0800, Widawsky, Ben wrote:
> On 22-01-31 23:19:48, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> >
> > Memory devices need the CDAT data from the device. This data is read
> > from a DOE mailbox which supports the CDAT protocol.
> >
> > Search the DOE auxiliary devices for the one which supports the CDAT
> > protocol. Cache that device to be used for future queries.
> >
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
[snip]
> >
> > diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> > index d4ae79b62a14..dcc55c4efd85 100644
> > --- a/drivers/cxl/pci.c
> > +++ b/drivers/cxl/pci.c
> > @@ -536,12 +536,53 @@ static int cxl_dvsec_ranges(struct cxl_dev_state *cxlds)
> > return rc;
> > }
> >
> > +static int cxl_match_cdat_doe_device(struct device *dev, const void *data)
> > +{
> > + const struct cxl_dev_state *cxlds = data;
> > + struct auxiliary_device *adev;
> > + struct pci_doe_dev *doe_dev;
> > +
> > + /* First determine if this auxiliary device belongs to the cxlds */
> > + if (cxlds->dev != dev->parent)
> > + return 0;
>
> I don't understand auxiliary bus but I'm wondering why it's checking the parent
> of the device?
auxiliary_find_device() iterates all the auxiliary devices in the system. This
check was a way for the match function to know if the auxiliary device belongs
to the cxlds we are interested in...
But now that I think about it we could have other auxiliary devices attached
which are not DOE... :-/ So this check is not complete.
FWIW I'm not thrilled with the way auxiliary_find_device() is defined. And now
that I look at it I think the only user of it currently is wrong. They too
have a check like this but it is after another check... :-/
I was hoping to avoid having a list of DOE devices in the cxlds and simply let
the auxiliary bus infrastructure do that somehow. IIRC Jonathan was thinking
along the same lines. I think he actually suggested auxiliary_find_device()...
It would be nice if I could have an aux_find_child() or something which
iterated the auxiliary devices attached to a particular parent device. I've
just not figured out exactly how to implement that better than what I did here.
>
> > +
> > + adev = to_auxiliary_dev(dev);
> > + doe_dev = container_of(adev, struct pci_doe_dev, adev);
> > +
> > + /* If it is one of ours check for the CDAT protocol */
> > + if (pci_doe_supports_prot(doe_dev, PCI_DVSEC_VENDOR_ID_CXL,
> > + CXL_DOE_PROTOCOL_TABLE_ACCESS))
> > + return 1;
> > +
> > + return 0;
> > +}
> > +
> > static int cxl_setup_doe_devices(struct cxl_dev_state *cxlds)
> > {
> > struct device *dev = cxlds->dev;
> > struct pci_dev *pdev = to_pci_dev(dev);
> > + struct auxiliary_device *adev;
> > + int rc;
> >
> > - return pci_doe_create_doe_devices(pdev);
> > + rc = pci_doe_create_doe_devices(pdev);
> > + if (rc)
> > + return rc;
> > +
> > + adev = auxiliary_find_device(NULL, cxlds, &cxl_match_cdat_doe_device);
> > +
> > + if (adev) {
> > + struct pci_doe_dev *doe_dev = container_of(adev,
> > + struct pci_doe_dev,
> > + adev);
> > +
> > + /*
> > + * No reference need be taken. The DOE device lifetime is
> > + * longer that the CXL device state lifetime
> > + */
>
> You're holding a reference to the adev here. Did you mean to drop it?
Does find device get a reference? ... Ah shoot I did not see that.
Yea the reference should be dropped somewhere.
Thanks,
Ira
>
> > + cxlds->cdat_doe = doe_dev;
> > + }
> > +
> > + return 0;
> > }
> >
> > static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> > --
> > 2.31.1
> >
next prev parent reply other threads:[~2022-02-01 22:18 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-01 7:19 [PATCH V6 00/10] CXL: Read CDAT and DSMAS data from the device ira.weiny
2022-02-01 7:19 ` [PATCH V6 01/10] PCI: Add vendor ID for the PCI SIG ira.weiny
2022-02-03 17:11 ` Bjorn Helgaas
2022-02-03 20:28 ` Ira Weiny
2022-02-01 7:19 ` [PATCH V6 02/10] PCI: Replace magic constant for PCI Sig Vendor ID ira.weiny
2022-02-04 21:16 ` Dan Williams
2022-02-04 21:49 ` Bjorn Helgaas
2022-03-15 21:48 ` Ira Weiny
2022-02-01 7:19 ` [PATCH V6 03/10] PCI/DOE: Add Data Object Exchange Aux Driver ira.weiny
2022-02-03 22:40 ` Bjorn Helgaas
2022-03-15 21:48 ` Ira Weiny
2022-02-09 0:59 ` Dan Williams
2022-02-09 10:13 ` Jonathan Cameron
2022-02-09 16:26 ` Dan Williams
2022-02-09 16:57 ` Jonathan Cameron
2022-02-09 19:57 ` Dan Williams
2022-02-10 21:51 ` Ira Weiny
2022-03-16 22:50 ` Ira Weiny
2022-03-17 19:37 ` Ira Weiny
2022-02-01 7:19 ` [PATCH V6 04/10] PCI/DOE: Introduce pci_doe_create_doe_devices ira.weiny
2022-02-03 22:44 ` Bjorn Helgaas
2022-02-04 14:51 ` Jonathan Cameron
2022-02-04 16:27 ` Bjorn Helgaas
2022-02-11 2:54 ` Dan Williams
2022-03-24 0:26 ` Ira Weiny
2022-03-24 14:05 ` Jonathan Cameron
2022-03-24 23:44 ` Ira Weiny
2022-03-25 12:02 ` Jonathan Cameron
2022-02-01 7:19 ` [PATCH V6 05/10] cxl/pci: Create DOE auxiliary devices ira.weiny
2022-02-01 7:19 ` [PATCH V6 06/10] cxl/pci: Find the DOE mailbox which supports CDAT ira.weiny
2022-02-01 18:49 ` Ben Widawsky
2022-02-01 22:18 ` Ira Weiny [this message]
2022-02-04 14:04 ` Jonathan Cameron
2022-02-01 7:19 ` [PATCH V6 07/10] cxl/mem: Read CDAT table ira.weiny
2022-02-04 13:46 ` Jonathan Cameron
2022-02-01 7:19 ` [PATCH V6 08/10] cxl/cdat: Introduce cdat_hdr_valid() ira.weiny
2022-02-01 18:56 ` Ben Widawsky
2022-02-01 22:29 ` Ira Weiny
2022-02-04 13:17 ` Jonathan Cameron
2022-02-01 7:19 ` [PATCH V6 09/10] cxl/mem: Retry reading CDAT on failure ira.weiny
2022-02-01 18:59 ` Ben Widawsky
2022-02-01 22:31 ` Ira Weiny
2022-02-04 13:20 ` Jonathan Cameron
2022-02-01 7:19 ` [PATCH V6 10/10] cxl/cdat: Parse out DSMAS data from CDAT table ira.weiny
2022-02-01 19:05 ` Ben Widawsky
2022-02-01 22:37 ` Ira Weiny
2022-02-04 13:33 ` Jonathan Cameron
2022-02-04 13:41 ` Jonathan Cameron
2022-02-04 13:40 ` Jonathan Cameron
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=20220201221841.GO785175@iweiny-DESK2.sc.intel.com \
--to=ira.weiny@intel.com \
--cc=Jonathan.Cameron@huawei.com \
--cc=alison.schofield@intel.com \
--cc=ben.widawsky@intel.com \
--cc=bhelgaas@google.com \
--cc=dan.j.williams@intel.com \
--cc=linux-cxl@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=vishal.l.verma@intel.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).