[PATCH v8 1/3] Documentation/devicetree: Add new property to specify the max link speed
helgaas at kernel.org
Fri Nov 11 14:24:16 PST 2016
On Tue, Oct 18, 2016 at 09:45:08AM +0800, Shawn Lin wrote:
> Some of the host drivers have the requirement of knowing whether the
> EP would never train at some link speed at all. For instance, on some
> boards, the link won't train at 5 GT/s but the host driver still sacrifice
> some cycle to wait for the resule of training at 5 GT/s as the host could
> actually support 5 GT/s. So we could parse this new property and make the
> host drivers be aware of these cases.
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>
Applied all three, with Rob's acks on the first two, to pci/host-rockchip
for v4.10, thanks!
> Changes in v8: None
> Changes in v7: None
> Changes in v6: None
> Changes in v5: None
> Changes in v4: None
> Changes in v3: None
> Changes in v2: None
> Documentation/devicetree/bindings/pci/pci.txt | 6 ++++++
> 1 file changed, 6 insertions(+)
> diff --git a/Documentation/devicetree/bindings/pci/pci.txt b/Documentation/devicetree/bindings/pci/pci.txt
> index 08dcfad..e7d97a3 100644
> --- a/Documentation/devicetree/bindings/pci/pci.txt
> +++ b/Documentation/devicetree/bindings/pci/pci.txt
> @@ -18,3 +18,9 @@ driver implementation may support the following properties:
> host bridges in the system, otherwise potentially conflicting domain numbers
> may be assigned to root buses behind different host bridges. The domain
> number for each host bridge in the system must be unique.
> +- max-link-speed:
> + If present this property specifies PCI gen for link capability. The host drivers
> + could add this as a strategy to avoid unnecessary operation for unsupported
> + link speed, for instance, trying to do training for unsupported link speed, etc.
> + Must be '4' for gen4, '3' for gen3, '2' for gen2, and '1' for gen1. Any other
> + values are invalid.
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