lkml.org 
[lkml]   [2021]   [Jun]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP bursting
From
Date
Hi

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(-)
>

\
 
 \ /
  Last update: 2021-06-17 23:02    [W:0.297 / U:0.128 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site