Thread (13 messages) 13 messages, 6 authors, 2020-04-17

Re: [RESENDING RFC PATCH 1/4] dt-bindings: usb: Add snps,consolidate-sgl & consolidate-sgl

From: Greg KH <gregkh@linuxfoundation.org>
Date: 2020-03-27 09:54:51
Also in: linux-usb, lkml

On Fri, Mar 27, 2020 at 03:11:56PM +0530, Tejas Joglekar wrote:
quoted hunk ↗ jump to hunk
This commit adds the documentation for consolidate-sgl, and
snps,consolidate-sgl 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 <redacted>
---
 Documentation/devicetree/bindings/usb/dwc3.txt     | 3 +++
 Documentation/devicetree/bindings/usb/usb-xhci.txt | 3 +++
 2 files changed, 6 insertions(+)
diff --git a/Documentation/devicetree/bindings/usb/dwc3.txt b/Documentation/devicetree/bindings/usb/dwc3.txt
index 9946ff9ba735..292d1f7969e4 100644
--- a/Documentation/devicetree/bindings/usb/dwc3.txt
+++ b/Documentation/devicetree/bindings/usb/dwc3.txt
@@ -104,6 +104,9 @@ 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,consolidate-sgl: 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..a90d853557ee 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
+  - consolidate-sgl: indicate 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.
Shouldn't this refer to the fact that the hardware is broken?  Otherwise
why would anyone know if they should, or should not, enable this option?

thanks,

greg k-h
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