Re: [PATCH v4] PCI: rockchip: Support property to specify the link capability

[Rob Herring <robh@kernel.org>]

On Thu, Oct 06, 2016 at 04:50:00PM +0800, Shawn Lin wrote:
> From: Brian Norris <briannorris@chromium.org>
> 
> rk3399 supports PCIe 2.x link speeds marginally at best, and on some
> boards, the link won't train at 5 GT/s at all. Rather than sacrifice 500
> ms waiting for training that will never happen, let's add a property
> from devicetree to specify link capability.
> 
> Signed-off-by: Brian Norris <briannorris@chromium.org>
> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
> 
> ---
> 
> Changes in v4:
> - define link_gen as u32
> - elaborate more for rockchip,max-link-speed on doc
> 
> Changes in v3:
> - Cast a warning for invalid max link speed and use gen1 for it.
>   That looks better than v2. (Suggested by Brian)
> 
> Changes in v2:
> - rename the property to rockchip,max-link-speed according to
>   Bjorn's recommendation and take some bits from imx6q-pcie to
>   make this requirement more consisent.
> 
>  .../devicetree/bindings/pci/rockchip-pcie.txt      |  4 ++
>  drivers/pci/host/pcie-rockchip.c                   | 63 ++++++++++++++--------
>  2 files changed, 44 insertions(+), 23 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> index ba67b39..9bb29de 100644
> --- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> +++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt
> @@ -42,6 +42,10 @@ Required properties:
>  Optional Property:
>  - ep-gpios: contain the entry for pre-reset gpio
>  - num-lanes: number of lanes to use
> +- rockchip,max-link-speed: Specify PCI gen for link capability. Must
> +	be '2' for gen2, and '1' for gen1, otherwise will default to gen1.
> +	For backward compatibility, if this property isn't assigned, we
> +	use gen2 by default.

Defaults to gen1 or gen2?

Let's drop rockchip and make this a common property. 

>  - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe.
>  - vpcie1v8-supply: The phandle to the 1.8v regulator to use for PCIe.
>  - vpcie0v9-supply: The phandle to the 0.9v regulator to use for PCIe.