On 5/21/2020 1:36 AM, Wesley Cheng wrote: > Changes in V2: > - Modified TXFIFO resizing logic to ensure that each EP is reserved a > FIFO. > - Removed dev_dbg() prints and fixed typos from patches > - Added some more description on the dt-bindings commit message > > Reviewed-by: Felipe Balbi <balbi@xxxxxxxxxx> > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > Sorry, please disregard the Reviewed-by tags in the patches. I added those mistakenly. > Currently, there is no functionality to allow for resizing the TXFIFOs, and > relying on the HW default setting for the TXFIFO depth. In most cases, the > HW default is probably sufficient, but for USB compositions that contain > multiple functions that require EP bursting, the default settings > might not be enough. Also to note, the current SW will assign an EP to a > function driver w/o checking to see if the TXFIFO size for that particular > EP is large enough. (this is a problem if there are multiple HW defined > values for the TXFIFO size) > > It is mentioned in the SNPS databook that a minimum of TX FIFO depth = 3 > is required for an EP that supports bursting. Otherwise, there may be > frequent occurences of bursts ending. For high bandwidth functions, > such as data tethering (protocols that support data aggregation), mass > storage, and media transfer protocol (over FFS), the bMaxBurst value can be > large, and a bigger TXFIFO depth may prove to be beneficial in terms of USB > throughput. (which can be associated to system access latency, etc...) It > allows for a more consistent burst of traffic, w/o any interruptions, as > data is readily available in the FIFO. > > With testing done using the mass storage function driver, the results show > that with a larger TXFIFO depth, the bandwidth increased significantly. > > Test Parameters: > - Platform: Qualcomm SM8150 > - bMaxBurst = 6 > - USB req size = 256kB > - Num of USB reqs = 16 > - USB Speed = Super-Speed > - Function Driver: Mass Storage (w/ ramdisk) > - Test Application: CrystalDiskMark > > Results: > > TXFIFO Depth = 3 max packets > > Test Case | Data Size | AVG tput (in MB/s) > ------------------------------------------- > Sequential|1 GB x | > Read |9 loops | 193.60 > | | 195.86 > | | 184.77 > | | 193.60 > ------------------------------------------- > > TXFIFO Depth = 6 max packets > > Test Case | Data Size | AVG tput (in MB/s) > ------------------------------------------- > Sequential|1 GB x | > Read |9 loops | 287.35 > | | 304.94 > | | 289.64 > | | 293.61 > ------------------------------------------- > > Wesley Cheng (3): > usb: dwc3: Resize TX FIFOs to meet EP bursting requirements > arm64: boot: dts: qcom: sm8150: Enable dynamic TX FIFO resize logic > dt-bindings: usb: dwc3: Add entry for tx-fifo-resize > > Documentation/devicetree/bindings/usb/dwc3.txt | 2 +- > arch/arm64/boot/dts/qcom/sm8150.dtsi | 1 + > drivers/usb/dwc3/core.c | 2 + > drivers/usb/dwc3/core.h | 8 ++ > drivers/usb/dwc3/ep0.c | 37 ++++++++- > drivers/usb/dwc3/gadget.c | 111 +++++++++++++++++++++++++ > 6 files changed, 159 insertions(+), 2 deletions(-) > -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
