Re: [PATCH v2 06/12] usb: devicetree: Introduce num-lanes and lsm

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Wed, Jul 22, 2020 at 07:12:39PM -0700, Thinh Nguyen wrote:
> According to USB 3.2 spec, a super-speed-plus device can operate at
> gen2x2, gen2x1, or gen1x2. Introduce "num-lanes" and
> "lane-speed-mantissa-gbps" properties for devices operating in
> super-speed-plus. If the USB controller device supports multiple lanes
> at different transfer rate, the user can specify the HW capability via
> these properties.
> 
> Signed-off-by: Thinh Nguyen <thinhn@xxxxxxxxxxxx>
> ---
> Changes in v2:
> - Make "num-lanes" and "lane-speed-mantissa-gbps" common USB properties
> 
>  Documentation/devicetree/bindings/usb/generic.txt | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
> index ba472e7aefc9..a8253da684af 100644
> --- a/Documentation/devicetree/bindings/usb/generic.txt
> +++ b/Documentation/devicetree/bindings/usb/generic.txt
> @@ -7,6 +7,17 @@ Optional properties:
>  			"low-speed". In case this isn't passed via DT, USB
>  			controllers should default to their maximum HW
>  			capability.
> + - num-lanes: tells USB controllers that we want to work up to a certain number
> +			of lanes. Valid arguments are 1 or 2. Apply if the
> +			maximum-speed is super-speed-plus. In case this isn't
> +			passed via DT, the USB controllers should default to
> +			their maximum HW capability.
> + - lane-speed-mantissa-gbps: tells USB controllers that we want the symmetric
> +			lanes to operate up to a certain rate in Gbps. Valid
> +			inputs are 5 or 10 (i.e. Gen 1/Gen 2 transfer rate).
> +			Apply if the maximum-speed is super-speed-plus. In case
> +			this isn't passed via DT, the USB controllers should
> +			default to their maximum HW capability.

This still leaves 'maximum-speed = "super-speed-plus"' ambiguous. Fix 
that please.

To put it another way, we already have one way to define USB speeds. 
Don't define a new and different way that only covers a fraction of the 
possibilities.

Rob



[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux