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    SubjectRe: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP bursting
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    Op 17-06-2021 om 11:58 schreef Wesley Cheng:
    > Changes in V10:
    > - Fixed compilation errors in config where OF is not used (error due to
    > unknown symbol for of_add_property()). Add of_add_property() stub.
    > - Fixed compilation warning for incorrect argument being passed to dwc3_mdwidth
    This fixes the OOPS I had in V9. I do not see any change in performance
    on Merrifield though.
    > Changes in V9:
    > - Fixed incorrect patch in series. Removed changes in DTSI, as dwc3-qcom will
    > add the property by default from the kernel.
    >
    > Changes in V8:
    > - Rebased to usb-testing
    > - Using devm_kzalloc for adding txfifo property in dwc3-qcom
    > - Removed DWC3 QCOM ACPI property for enabling the txfifo resize
    >
    > Changes in V7:
    > - Added a new property tx-fifo-max-num for limiting how much fifo space the
    > resizing logic can allocate for endpoints with large burst values. This
    > can differ across platforms, and tie in closely with overall system latency.
    > - Added recommended checks for DWC32.
    > - Added changes to set the tx-fifo-resize property from dwc3-qcom by default
    > instead of modifying the current DTSI files.
    > - Added comments on all APIs/variables introduced.
    > - Updated the DWC3 YAML to include a better description of the tx-fifo-resize
    > property and added an entry for tx-fifo-max-num.
    >
    > Changes in V6:
    > - Rebased patches to usb-testing.
    > - Renamed to PATCH series instead of RFC.
    > - Checking for fs_descriptors instead of ss_descriptors for determining the
    > endpoint count for a particular configuration.
    > - Re-ordered patch series to fix patch dependencies.
    >
    > Changes in V5:
    > - Added check_config() logic, which is used to communicate the number of EPs
    > used in a particular configuration. Based on this, the DWC3 gadget driver
    > has the ability to know the maximum number of eps utilized in all configs.
    > This helps reduce unnecessary allocation to unused eps, and will catch fifo
    > allocation issues at bind() time.
    > - Fixed variable declaration to single line per variable, and reverse xmas.
    > - Created a helper for fifo clearing, which is used by ep0.c
    >
    > Changes in V4:
    > - Removed struct dwc3* as an argument for dwc3_gadget_resize_tx_fifos()
    > - Removed WARN_ON(1) in case we run out of fifo space
    >
    > Changes in V3:
    > - Removed "Reviewed-by" tags
    > - Renamed series back to RFC
    > - Modified logic to ensure that fifo_size is reset if we pass the minimum
    > threshold. Tested with binding multiple FDs requesting 6 FIFOs.
    >
    > 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
    >
    > 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 (6):
    > usb: gadget: udc: core: Introduce check_config to verify USB
    > configuration
    > usb: gadget: configfs: Check USB configuration before adding
    > usb: dwc3: Resize TX FIFOs to meet EP bursting requirements
    > of: Add stub for of_add_property()
    > usb: dwc3: dwc3-qcom: Enable tx-fifo-resize property by default
    > dt-bindings: usb: dwc3: Update dwc3 TX fifo properties
    >
    > .../devicetree/bindings/usb/snps,dwc3.yaml | 15 +-
    > drivers/usb/dwc3/core.c | 9 +
    > drivers/usb/dwc3/core.h | 15 ++
    > drivers/usb/dwc3/dwc3-qcom.c | 9 +
    > drivers/usb/dwc3/ep0.c | 2 +
    > drivers/usb/dwc3/gadget.c | 212 +++++++++++++++++++++
    > drivers/usb/gadget/configfs.c | 22 +++
    > drivers/usb/gadget/udc/core.c | 25 +++
    > include/linux/of.h | 5 +
    > include/linux/usb/gadget.h | 5 +
    > 10 files changed, 317 insertions(+), 2 deletions(-)
    >

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