From: Wesley Cheng <wcheng@codeaurora.org>
To: agross@kernel.org, bjorn.andersson@linaro.org,
robh+dt@kernel.org, balbi@kernel.org, gregkh@linuxfoundation.org
Cc: linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org,
jackp@codeaurora.org
Subject: Re: [PATCH v2 0/3] Re-introduce TX FIFO resize for larger EP bursting
Date: Thu, 21 May 2020 10:37:10 -0700 [thread overview]
Message-ID: <1e2e9c1b-fcd9-9e03-da86-a46e541a1480@codeaurora.org> (raw)
In-Reply-To: <1590050169-30747-1-git-send-email-wcheng@codeaurora.org>
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@kernel.org>
> Reviewed-by: Rob Herring <robh@kernel.org>
>
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
next prev parent reply other threads:[~2020-05-21 17:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 8:36 [PATCH v2 0/3] Re-introduce TX FIFO resize for larger EP bursting Wesley Cheng
2020-05-21 8:36 ` [PATCH v2 1/3] usb: dwc3: Resize TX FIFOs to meet EP bursting requirements Wesley Cheng
2020-05-21 8:36 ` [PATCH v2 2/3] arm64: boot: dts: qcom: sm8150: Enable dynamic TX FIFO resize logic Wesley Cheng
2020-05-21 8:36 ` [PATCH v2 3/3] dt-bindings: usb: dwc3: Add entry for tx-fifo-resize Wesley Cheng
2020-05-21 17:37 ` Wesley Cheng [this message]
2020-05-22 9:54 ` [PATCH v2 0/3] Re-introduce TX FIFO resize for larger EP bursting Felipe Balbi
2020-05-22 17:49 ` Wesley Cheng
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