From: "Spassov, Stanislav" <stanspas@amazon.de>
To: "Spassov, Stanislav" <stanspas@amazon.de>,
"rafael@kernel.org" <rafael@kernel.org>
Cc: "corbet@lwn.net" <corbet@lwn.net>,
"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
"ashok.raj@intel.com" <ashok.raj@intel.com>,
"okaya@kernel.org" <okaya@kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"lkp@intel.com" <lkp@intel.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"Schoenherr, Jan H." <jschoenh@amazon.de>,
"rajatja@google.com" <rajatja@google.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"bhelgaas@google.com" <bhelgaas@google.com>,
"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>
Subject: Re: [PATCH v3 04/17] PCI: Do not override delay for D0->D3hot transition
Date: Sat, 7 Mar 2020 10:58:15 +0000 [thread overview]
Message-ID: <5556ec9ccb09796b8555db51a0079dcbd7a49a9e.camel@amazon.de> (raw)
In-Reply-To: <CAJZ5v0hVFGqWsZbHwYu2uJrdwzVp1m-HDaTCS+A-+qpw5FwuQQ@mail.gmail.com>
On Tue, 2020-03-03 at 19:57 +0100, Rafael J. Wysocki wrote:
> > Both specifications that document mechanisms for overriding the
> > D3hot->D0 waiting time only speak of this specific direction.
> > Nothing is mentioned about the opposite (D*->D3hot) except for
> > the default value of 10ms in PCI Express Base Specification
> > r5.0 (May 22, 2019), Section 5.9 "State Transition Recovery Time
> > Requirements".
>
> Unless you have a specific example of a system on which the current
> code doesn't work (and which should be mentioned here), I don't think
> that it is a good idea to make this change.
>
I do not have a specific example for a failing system here. The intention
is purely to bring the code in line with what
the spec says (or in this case:
what the spec does not say).
> There are systems in which it would make a measurable difference in
> things like the time it takes to suspend the system.
This patch only affects the D0->D3hot delay within pci_pm_reset().
(I will make this more explicit in the commit title/message.)
The PM reset is only ever invoked from __pci_reset_function_locked()
and pci_probe_reset_function(). Specifically, pci_set_power_state() is untouched.
I am not well versed into the system suspend code, but unless we are resetting the
devices there, this patch should not affect system suspend time at all.
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
next prev parent reply other threads:[~2020-03-07 10:58 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-03 13:28 [PATCH v3 00/17] Improve PCI device post-reset readiness polling Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 01/17] PCI: Fall back to slot/bus reset if softer methods timeout Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 02/17] PCI: Remove unused PCI_PM_BUS_WAIT Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 03/17] PCI: Use pci_bridge_wait_for_secondary_bus after SBR Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 04/17] PCI: Do not override delay for D0->D3hot transition Stanislav Spassov
2020-03-03 18:57 ` Rafael J. Wysocki
2020-03-07 10:58 ` Spassov, Stanislav [this message]
2020-03-03 13:28 ` [PATCH v3 05/17] PCI: Fix handling of _DSM 8 (avoiding reset delays) Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 06/17] PCI: Fix us->ms conversion in pci_acpi_optimize_delay Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 07/17] PCI: Clean up and document PM/reset delays Stanislav Spassov
2020-03-03 19:03 ` Rafael J. Wysocki
2020-03-07 11:30 ` Spassov, Stanislav
2020-03-03 13:28 ` [PATCH v3 08/17] PCI: Add more delay overrides to struct pci_dev Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 09/17] PCI: Generalize pci_bus_max_d3cold_delay to pci_bus_max_delay Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 10/17] PCI: Use correct delay in pci_bridge_wait_for_secondary_bus Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 11/17] PCI: Refactor pci_dev_wait to remove timeout parameter Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 12/17] PCI: Refactor pci_dev_wait to take pci_init_event Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 13/17] PCI: Cache CRS Software Visibiliy in struct pci_dev Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 14/17] PCI: Introduce per-device reset_ready_poll override Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 15/17] PCI: Refactor polling loop out of pci_dev_wait Stanislav Spassov
2020-03-03 13:28 ` [PATCH v3 16/17] PCI: Add CRS handling to pci_dev_wait() Stanislav Spassov
2020-03-05 17:56 ` Raj, Ashok
2020-03-06 18:07 ` Spassov, Stanislav
2020-03-03 13:28 ` [PATCH v3 17/17] PCI: Lower PCIE_RESET_READY_POLL_MS from 1m to 1s Stanislav Spassov
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