From: Bjorn Helgaas <bhelgaas@google.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: linux-pci@vger.kernel.org,
Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Subject: Re: [PATCH 2/5] pciehp: Don't enable presence notification while surprise removal is not supported.
Date: Wed, 11 Jul 2012 13:56:55 -0600 [thread overview]
Message-ID: <CAErSpo7f1hvQ2sg8TTu-d2dy1ST8xNEfR0odESihQtRh=KMi5A@mail.gmail.com> (raw)
In-Reply-To: <CAE9FiQVbaYszsqq6WYENQu18a52m2fD9svtdFV2y4DeDnYWJcA@mail.gmail.com>
On Wed, Jul 11, 2012 at 12:49 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Wed, Jul 11, 2012 at 11:15 AM, Bjorn Helgaas <bhelgaas@google.com> wrote:
>>
>> What's the connection with HP_SUPR_RM()? Is it just a coincidence
>> that chipsets that set the "Hot-Plug Surprise" bit don't have this
>> problem with the Presence Detect State bit?
>>
>> Using HP_SUPR_RM() seems like a totally bogus way to work around a
>> presence detect issue.
>
> then we should blame the spec.
What specifically are you referring to? I see this Presence Detect State text:
Presence Detect State – This bit indicates the presence of an
adapter in the slot, reflected by the logical “OR” of the Physical
Layer in-band presence detect mechanism and, if present, any
out-of-band presence detect mechanism defined for the slot’s
corresponding form factor. Note that the in-band presence
detect mechanism requires that power be applied to an adapter
for its presence to be detected. Consequently, form factors that
require a power controller for hot-plug must implement a
physical pin presence detect mechanism.
But I don't yet see the connection with the Hot-Plug Surprise bit.
> and if you do the above changing, when plug the card into system,
> kernel will bring that card online automatically without press
> attention button.
> that will be big change.
I don't want to make a fundamental change in behavior like that. I'm
just trying to understand why we should handle Presence Detect
differently based on the Hot-Plug Surprise bit.
The attention button is optional. What happens today when you plug a
card into a slot with no attention button?
next prev parent reply other threads:[~2012-07-11 19:57 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-23 7:42 [PATCH 0/5] PCI: hotplug related misc patches Yinghai Lu
2012-06-23 7:42 ` [PATCH 1/5] PCI, acpiphp: remove not used res_lock Yinghai Lu
2012-06-23 7:42 ` [PATCH 2/5] pciehp: Don't enable presence notification while surprise removal is not supported Yinghai Lu
2012-06-26 1:26 ` Kaneshige, Kenji
2012-06-26 18:03 ` Yinghai Lu
2012-07-10 22:56 ` Bjorn Helgaas
2012-07-10 23:12 ` Yinghai Lu
2012-07-10 23:28 ` Bjorn Helgaas
2012-07-10 23:40 ` Yinghai Lu
2012-07-11 16:21 ` Bjorn Helgaas
2012-07-11 17:58 ` Yinghai Lu
2012-07-11 18:15 ` Bjorn Helgaas
2012-07-11 18:49 ` Yinghai Lu
2012-07-11 19:56 ` Bjorn Helgaas [this message]
2012-07-11 20:28 ` Yinghai Lu
2012-07-11 20:48 ` Bjorn Helgaas
2012-07-11 20:56 ` Yinghai Lu
2012-07-11 22:24 ` Bjorn Helgaas
2012-07-12 0:05 ` Yinghai Lu
2012-07-12 20:20 ` Bjorn Helgaas
2012-07-13 0:19 ` Yinghai Lu
2012-07-13 15:30 ` Bjorn Helgaas
2012-07-13 18:07 ` Yinghai Lu
2012-06-23 7:42 ` [PATCH 3/5] PCI, acpiphp: Merge acpiphp_debug and debug Yinghai Lu
2012-06-23 7:42 ` [PATCH 4/5] PCI, acpiphp: add is_hotplug_bridge detection Yinghai Lu
2012-07-11 15:50 ` Bjorn Helgaas
2012-07-11 17:14 ` Jason Baron
2012-07-11 19:42 ` Bjorn Helgaas
2012-07-16 16:05 ` Bjorn Helgaas
2012-07-17 14:14 ` Jason Baron
2012-08-15 19:36 ` Bjorn Helgaas
2012-08-20 14:35 ` Jason Baron
2012-08-22 23:19 ` Bjorn Helgaas
2012-09-04 20:55 ` Jason Baron
2012-06-23 7:42 ` [PATCH 5/5] PCI: add root bus children dev's res to fail list Yinghai Lu
2012-07-10 19:30 ` [PATCH 0/5] PCI: hotplug related misc patches Yinghai Lu
2012-07-11 18:32 ` Bjorn Helgaas
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