Re: [PATCH v3 0/4] Add logic to consolidate TRBs for Synopsys xHC

[Tejas Joglekar <Tejas.Joglekar@synopsys.com>]

Hi Mathias,
   Will this be added to your next branch ?
On 5/27/2020 4:10 PM, 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.
> 
> Changes since v2:
>  - Modified the xhci_unmap_temp_buffer function to unmap dma and clear
>    the dma flag
>  - Removed RFC tag
> 
> Changes since v1:
>  - Comments from Greg are addressed on [PATCH 4/4] and [PATCH 1/4]
>  - Renamed the property and quirk as in other patches based on [PATCH 1/4]
> 
> Tejas Joglekar (4):
>   dt-bindings: usb: Add documentation for SG trb cache size quirk
>   usb: xhci: Set quirk for XHCI_SG_TRB_CACHE_SIZE_QUIRK
>   usb: dwc3: Add device property sgl-trb-cache-size-quirk
>   usb: xhci: Use temporary buffer to consolidate SG
> 
>  Documentation/devicetree/bindings/usb/dwc3.txt     |   4 +
>  Documentation/devicetree/bindings/usb/usb-xhci.txt |   3 +
>  drivers/usb/dwc3/core.c                            |   2 +
>  drivers/usb/dwc3/core.h                            |   2 +
>  drivers/usb/dwc3/dwc3-haps.c                       |   1 +
>  drivers/usb/dwc3/host.c                            |   6 +-
>  drivers/usb/host/xhci-pci.c                        |   3 +
>  drivers/usb/host/xhci-plat.c                       |   4 +
>  drivers/usb/host/xhci-ring.c                       |   2 +-
>  drivers/usb/host/xhci.c                            | 135 +++++++++++++++++++++
>  drivers/usb/host/xhci.h                            |   5 +
>  11 files changed, 165 insertions(+), 2 deletions(-)
> 

Thanks and Regards,
 Tejas Joglekar