From: Ira Weiny <ira.weiny@intel.com>
To: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"Li, Ming" <ming4.li@intel.com>,
Bjorn Helgaas <helgaas@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
Lukas Wunner <lukas@wunner.de>,
Alison Schofield <alison.schofield@intel.com>,
"Vishal Verma" <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
"Ben Widawsky" <bwidawsk@kernel.org>,
<linux-kernel@vger.kernel.org>, <linux-cxl@vger.kernel.org>,
<linux-pci@vger.kernel.org>
Subject: Re: [PATCH V14 3/7] PCI/DOE: Add DOE mailbox support functions
Date: Tue, 19 Jul 2022 12:50:56 -0700 [thread overview]
Message-ID: <YtcLIAIlSKQpzysl@iweiny-desk3> (raw)
In-Reply-To: <YtcC9qYo1lOGZ/83@iweiny-desk3>
On Tue, Jul 19, 2022 at 12:16:06PM -0700, Ira wrote:
> On Tue, Jul 19, 2022 at 05:35:53PM +0100, Jonathan Cameron wrote:
[snip]
> > Hi Ira,
> >
> > Thanks for persisting with this!
> >
> > So, I think this works, but there is at least one 'sleep' I can't
> > see a purpose for. I think it's just a left over from refactoring.
> >
> > A few other more trivial things inline.
[snip]
> > > +
> > > +#define PCI_DOE_BUSY_MAX_RETRIES 16
> > Left over from removed code.
>
> I think Dan may have taken these. If so I'll send a clean up. If not I can
> spin. Let me check.
I'm spinning a v15 of this patch.
[snip]
>
> >
> > > + if (rc) {
> > > + /*
> > > + * The specification does not provide any guidance on how to
> > > + * resolve conflicting requests from other entities.
> > > + * Furthermore, it is likely that busy will not be detected
> > > + * most of the time. Flag any detection of status busy with an
> > > + * error.
> > > + */
> > > + if (rc == -EBUSY)
> > > + dev_err_ratelimited(&pdev->dev, "[%x] busy detected; another entity is sending conflicting requests\n",
> > > + offset);
> > > + signal_task_abort(task, rc);
> > > + return;
> > > + }
> > > +
> > > + timeout_jiffies = jiffies + PCI_DOE_TIMEOUT;
> > > + rc = pci_doe_wait(doe_mb, PCI_DOE_POLL_INTERVAL);
> >
> > What's this particular wait for? I think you can just move directly to checking
> > if the response is ready.
>
> We could but I assume it will take at least some time to process the request.
> So it seemed best to wait and then check.
>
> But of course we all know that also used to wait for an IRQ as an option. :-/
>
> I'm really on the fence here because I don't think it really matters. We are
> sleeping so it does not really affect the system much and this is not a
> performance path. If we were spinning I would agree with you.
I've deferred to your expertise here and removed the extra wait.
Ira
next prev parent reply other threads:[~2022-07-19 19:51 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-15 3:04 [PATCH V14 0/7] CXL: Read CDAT ira.weiny
2022-07-15 3:04 ` [PATCH V14 1/7] PCI: Add vendor ID for the PCI SIG ira.weiny
2022-07-15 3:04 ` [PATCH V14 2/7] PCI: Replace magic constant for PCI Sig Vendor ID ira.weiny
2022-07-15 3:04 ` [PATCH V14 3/7] PCI/DOE: Add DOE mailbox support functions ira.weiny
2022-07-19 16:35 ` Jonathan Cameron
2022-07-19 19:16 ` Ira Weiny
2022-07-19 19:50 ` Ira Weiny [this message]
2022-07-20 11:24 ` Jonathan Cameron
2022-07-15 3:04 ` [PATCH V14 4/7] cxl/pci: Create PCI DOE mailbox's for memory devices ira.weiny
2022-07-19 16:38 ` Jonathan Cameron
2022-07-15 3:04 ` [PATCH V14 5/7] driver-core: Introduce BIN_ATTR_ADMIN_{RO,RW} ira.weiny
2022-07-19 16:39 ` Jonathan Cameron
2022-07-15 3:04 ` [PATCH V14 6/7] cxl/port: Read CDAT table ira.weiny
2022-07-16 3:27 ` Dan Williams
2022-07-19 1:19 ` Dan Williams
2022-07-15 3:04 ` [PATCH V14 7/7] cxl/port: Introduce cxl_cdat_valid() ira.weiny
2022-07-16 2:26 ` Dan Williams
2022-07-19 16:47 ` Jonathan Cameron
2022-07-19 15:21 ` [PATCH V14 0/7] CXL: Read CDAT Jonathan Cameron
2022-07-19 19:23 ` Dan Williams
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