On Fri, Mar 27, 2020 at 02:22:23PM +0530, Tejas Joglekar wrote: > The Synopsys xHC has an internal TRB cache of size TRB_CACHE_SIZE for > each endpoint. The default value for TRB_CACHE_SIZE is 16 for SS and 8 > for HS. The controller loads and updates the TRB cache from the > transfer ring in system memory whenever the driver issues a start > transfer or update transfer command. > > For chained TRBs, the Synopsys xHC requires that the total amount of > bytes for all TRBs loaded in the TRB cache be greater than or equal to > 1 MPS. Or the chain ends within the TRB cache (with a last TRB). > > If this requirement is not met, the controller will not be able to > send or receive a packet and it will hang causing a driver timeout and > error. > > This patch set adds logic to the XHCI driver to detect and prevent this > from happening along with the quirk to enable this logic for Synopsys > HAPS platform. > > Based on Mathias's feedback on previous implementation where consolidation > was done in TRB cache, with this patch series the implementation is done > during mapping of the URB by consolidating the SG list into a temporary > buffer if the SG list buffer sizes within TRB_CACHE_SIZE is less than MPS. > > > Tejas Joglekar (4): > dt-bindings: usb: Add snps,consolidate-sgl & consolidate-sgl > usb: xhci: Set quirk for XHCI_CONSOLIDATE_SG_LIST > usb: dwc3: Add device property consolidate-sgl > usb: xhci: Use temporary buffer to consolidate SG > > Resending as 'umlaut' is not accepted by some servers in email. Only patch 4/4 seems to have gone through :(
