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From: Lukas Wunner <lukas@wunner.de>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
	Sathyanarayanan Kuppuswamy Natarajan 
	<sathyanarayanan.nkuppuswamy@gmail.com>,
	Kuppuswamy Sathyanarayanan 
	<sathyanarayanan.kuppuswamy@linux.intel.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Linux PCI <linux-pci@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Keith Busch <kbusch@kernel.org>,
	knsathya@kernel.org, Sinan Kaya <okaya@kernel.org>
Subject: Re: [PATCH v2 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered
Date: Wed, 17 Mar 2021 20:40:09 +0100	[thread overview]
Message-ID: <20210317194009.GA9515@wunner.de> (raw)
In-Reply-To: <20210317192241.GE52280@otc-nc-03>

On Wed, Mar 17, 2021 at 12:22:41PM -0700, Raj, Ashok wrote:
> On Wed, Mar 17, 2021 at 08:09:52PM +0100, Lukas Wunner wrote:
> > On Wed, Mar 17, 2021 at 10:45:21AM -0700, Dan Williams wrote:
> > > Ah, ok, we're missing a flush of the hotplug event handler after the
> > > link is up to make sure the hotplug handler does not see the Link Up.
> > > I'm not immediately seeing how the new proposal ensures that there is
> > > no Link Up event still in flight after DPC completes its work.
> > > Wouldn't it be required to throw away Link Up to Link Up transitions?
> > 
> > If you look at the new code added to pciehp_ist() by my patch...
> > 
> >       atomic_and(~PCI_EXP_SLTSTA_DLLSC, &ctrl->pending_events);
> >       if (pciehp_check_link_active(ctrl) > 0)
> >               events &= ~PCI_EXP_SLTSTA_DLLSC;
> 
> When you have a Surprise Link Down and without any DPC, the link trains
> back up. Aren't we expected to take the slot down and add it as if a remove
> and add happens?
> 
> without this change if slot-status == ON_STATE, DLLSC means we would power
> the slot off. Then we check link_active and bring the slot back on isn't
> it?

Yes to both questions.  That behavior should still be the same
with the patch.  Do you think it's not?

  reply	other threads:[~2021-03-17 19:40 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-13  3:32 [PATCH v2 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered sathyanarayanan.kuppuswamy
2021-03-13  3:35 ` Kuppuswamy, Sathyanarayanan
2021-03-17  4:13 ` Lukas Wunner
2021-03-17  5:08   ` Dan Williams
2021-03-17  5:31     ` Lukas Wunner
2021-03-17 16:31       ` Dan Williams
2021-03-17 17:19         ` Sathyanarayanan Kuppuswamy Natarajan
2021-03-17 17:45           ` Dan Williams
2021-03-17 17:54             ` Sathyanarayanan Kuppuswamy Natarajan
2021-03-17 19:01               ` Lukas Wunner
2021-03-17 20:02                 ` Kuppuswamy, Sathyanarayanan
2021-03-18 15:35                   ` Sinan Kaya
2021-03-28  9:53                   ` Lukas Wunner
2021-03-17 19:09             ` Lukas Wunner
2021-03-17 19:22               ` Raj, Ashok
2021-03-17 19:40                 ` Lukas Wunner [this message]
2021-03-28  5:49   ` Kuppuswamy, Sathyanarayanan
2021-03-28  9:07     ` Lukas Wunner

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