From: Bjorn Helgaas <helgaas@kernel.org>
To: "Kuppuswamy,
Sathyanarayanan" <sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, ashok.raj@intel.com,
dan.j.williams@intel.com, keith.busch@intel.com,
knsathya@kernel.org, Lukas Wunner <lukas@wunner.de>
Subject: Re: [PATCH v1 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered
Date: Fri, 12 Mar 2021 17:14:16 -0600 [thread overview]
Message-ID: <20210312231416.GA2304029@bjorn-Precision-5520> (raw)
In-Reply-To: <a137e4aa-22fb-5683-7d58-847408c6bf2b@linux.intel.com>
On Fri, Mar 12, 2021 at 02:11:03PM -0800, Kuppuswamy, Sathyanarayanan wrote:
> On 3/12/21 1:33 PM, Bjorn Helgaas wrote:
> > On Mon, Mar 08, 2021 at 10:34:10PM -0800, sathyanarayanan.kuppuswamy@linux.intel.com wrote:
> > > From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
> > > +bool is_dpc_reset_active(struct pci_dev *dev)
> > > +{
> > > + struct pci_host_bridge *host = pci_find_host_bridge(dev->bus);
> > > + u16 status;
> > > +
> > > + if (!dev->dpc_cap)
> > > + return false;
> > > +
> > > + /*
> > > + * If DPC is owned by firmware and EDR is not supported, there is
> > > + * no race between hotplug and DPC recovery handler. So return
> > > + * false.
> > > + */
> > > + if (!host->native_dpc && !IS_ENABLED(CONFIG_PCIE_EDR))
> > > + return false;
> > > +
> > > + if (atomic_read_acquire(&dev->dpc_reset_active))
> > > + return true;
> > > +
> > > + pci_read_config_word(dev, dev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
> > > +
> > > + return !!(status & PCI_EXP_DPC_STATUS_TRIGGER);
> >
> > I know it's somewhat common in drivers/pci/, but I'm not really a
> > big fan of "!!".
> I can change it to use ternary operator.
> (status & PCI_EXP_DPC_STATUS_TRIGGER) ? true : false;
Ternary isn't terrible, but what's wrong with:
if (status & PCI_EXP_DPC_STATUS_TRIGGER)
return true;
return false;
which matches the style of the rest of the function.
Looking at this again, we return "true" if either dpc_reset_active or
PCI_EXP_DPC_STATUS_TRIGGER. I haven't worked this all out, but that
pattern feels racy. I guess the thought is that if
PCI_EXP_DPC_STATUS_TRIGGER is set, dpc_reset_link() will be invoked
soon and we don't want to interfere?
next prev parent reply other threads:[~2021-03-12 23:15 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-09 6:34 [PATCH v1 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered sathyanarayanan.kuppuswamy
2021-03-12 21:33 ` Bjorn Helgaas
2021-03-12 22:11 ` Kuppuswamy, Sathyanarayanan
2021-03-12 23:14 ` Bjorn Helgaas [this message]
2021-03-12 23:26 ` Kuppuswamy, Sathyanarayanan
2021-03-13 0:37 ` Dan Williams
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=20210312231416.GA2304029@bjorn-Precision-5520 \
--to=helgaas@kernel.org \
--cc=ashok.raj@intel.com \
--cc=bhelgaas@google.com \
--cc=dan.j.williams@intel.com \
--cc=keith.busch@intel.com \
--cc=knsathya@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=lukas@wunner.de \
--cc=sathyanarayanan.kuppuswamy@linux.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).