Re: [RFC PATCH v2 1/4] dt-bindings: usb: Add documentation for SG trb cache size quirk

[Rob Herring <robh@kernel.org>]

On Tue, Apr 21, 2020 at 03:18:09PM +0530, Tejas Joglekar wrote:
> This commit adds the documentation for sgl-trb-cache-size-quirk, and
> snps,sgl-trb-cache-size-quirk property. These when set enables the
> quirk for XHCI driver for consolidation of sg list into a temporary
> buffer when small buffer sizes are scattered over the sg list not
> making up to MPS or total transfer size within TRB cache size with
> Synopsys xHC.
> 
> Signed-off-by: Tejas Joglekar <joglekar@synopsys.com>
> ---
>  Changes in v2:
>  - Renamed the property
> 
>  Documentation/devicetree/bindings/usb/dwc3.txt     | 4 ++++
>  Documentation/devicetree/bindings/usb/usb-xhci.txt | 3 +++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
> index 9946ff9ba735..6d0418ee4dbd 100644
> --- a/Documentation/devicetree/bindings/usb/dwc3.txt
> +++ b/Documentation/devicetree/bindings/usb/dwc3.txt
> @@ -104,6 +104,10 @@ Optional properties:
>  			this and tx-thr-num-pkt-prd to a valid, non-zero value
>  			1-16 (DWC_usb31 programming guide section 1.2.3) to
>  			enable periodic ESS TX threshold.
> + - snps,sgl-trb-cache-size-quirk: enable sg list consolidation - host mode
> +			only. Set to use SG buffers of at least MPS size
> +			by consolidating smaller SG buffers list into a
> +			single buffer.
>  
>   - <DEPRECATED> tx-fifo-resize: determines if the FIFO *has* to be reallocated.
>   - snps,incr-burst-type-adjustment: Value for INCR burst type of GSBUSCFG0
> diff --git a/Documentation/devicetree/bindings/usb/usb-xhci.txt b/Documentation/devicetree/bindings/usb/usb-xhci.txt
> index 3f378951d624..14d900474894 100644
> --- a/Documentation/devicetree/bindings/usb/usb-xhci.txt
> +++ b/Documentation/devicetree/bindings/usb/usb-xhci.txt
> @@ -43,6 +43,9 @@ Optional properties:
>    - quirk-broken-port-ped: set if the controller has broken port disable mechanism
>    - imod-interval-ns: default interrupt moderation interval is 5000ns
>    - phys : see usb-hcd.yaml in the current directory
> +  - sgl-trb-cache-size-quirk: set if you need to consolidate sg list into a
> +    temporary buffer when small SG buffer sizes does not make upto MPS
> +    size or total transfer size across the TRB cache size.

Why do we have 2 different names?

>  
>  additionally the properties from usb-hcd.yaml (in the current directory) are
>  supported.
> -- 
> 2.11.0
>