From: Alex Williamson <alex.williamson@redhat.com>
To: Geetha sowjanya <gakula@caviumnetworks.com>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
geethasowjanya.akula@gmail.com, robert.richter@cavium.com,
jcm@redhat.com, bhelgaas@google.com, sgoutham@cavium.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] PCI/PM: Set D3 power state only if the end device supports it.
Date: Wed, 31 May 2017 06:43:40 -0600 [thread overview]
Message-ID: <20170531064340.0dcec477@w520.home> (raw)
In-Reply-To: <1496230412-19028-1-git-send-email-gakula@caviumnetworks.com>
On Wed, 31 May 2017 17:03:32 +0530
Geetha sowjanya <gakula@caviumnetworks.com> wrote:
> Pci driver doesn't check if the device supports D3hot/D3cold power states
> while setting these power states. The device that doesn't support these
> states will fail when a driver like vfio try to do D0->D3 power transition.
That's because support for D0 and D3 device states is REQUIRED by the
PCIe spec (Rev 3.1a, 7.6). Is this yet more non-spec compliance?
Thanks,
Alex
> This patch adds a check that allows to set D3 power state only
> for the supported devices.
>
> Signed-off-by: Geetha sowjanya <gakula@caviumnetworks.com>
> ---
> drivers/pci/pci.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 563901c..cadd046 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -661,7 +661,8 @@ static int pci_raw_set_power_state(struct pci_dev *dev, pci_power_t state)
>
> /* check if this device supports the desired state */
> if ((state == PCI_D1 && !dev->d1_support)
> - || (state == PCI_D2 && !dev->d2_support))
> + || (state == PCI_D2 && !dev->d2_support)
> + || (state == PCI_D3hot && !pci_pme_capable(dev, state)))
> return -EIO;
>
> pci_read_config_word(dev, dev->pm_cap + PCI_PM_CTRL, &pmcsr);
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next prev parent reply other threads:[~2017-05-31 12:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-31 11:33 [PATCH] PCI/PM: Set D3 power state only if the end device supports it Geetha sowjanya
2017-05-31 12:43 ` Alex Williamson [this message]
2017-06-02 5:44 ` Geetha Akula
2017-06-05 22:00 ` Alex Williamson
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