Re: [PATCH] PCI: Wait for 50ms after bridge is powered up

["Rafael J. Wysocki" <rafael@kernel.org>]

On Wed, May 25, 2016 at 5:04 PM, Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
> The PCI PM 1.2 specification requires minimum of 50ms before function on a
> bus is accessed after the bus is transitioned from B2 to B0. Now that we
> actually power down bridges we should make sure the specification is
> followed accordingly.
>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

ACK

> ---
> Hi Bjorn,
>
> Since this is only needed when bridges are powered down, I think it makes
> sense to put this to your pci/pm branch.
>
>  drivers/pci/pci.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index e785dc260e72..e645a3d4f2e0 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -2361,7 +2361,12 @@ void pci_pm_init(struct pci_dev *dev)
>         }
>
>         dev->pm_cap = pm;
> -       dev->d3_delay = PCI_PM_D3_WAIT;
> +       /*
> +        * PCI PM 1.2 specification requires minimum of 50ms before any
> +        * function on the bus is accessed after the bus is transitioned
> +        * from B2 to B0.
> +        */
> +       dev->d3_delay = pci_is_bridge(dev) ? PCI_PM_BUS_WAIT : PCI_PM_D3_WAIT;
>         dev->d3cold_delay = PCI_PM_D3COLD_WAIT;
>         dev->bridge_d3 = pci_bridge_d3_possible(dev);
>         dev->d3cold_allowed = true;
> --
> 2.8.1
>
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