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Date:   Sat, 26 Jun 2021 00:31:00 +0200
From:   Ferry Toth <fntoth@...il.com>
To:     Wesley Cheng <wcheng@...eaurora.org>, balbi@...nel.org,
        gregkh@...uxfoundation.org, robh+dt@...nel.org, agross@...nel.org,
        bjorn.andersson@...aro.org, frowand.list@...il.com
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        jackp@...eaurora.org, heikki.krogerus@...ux.intel.com,
        andy.shevchenko@...il.com
Subject: Re: [PATCH v10 0/6] Re-introduce TX FIFO resize for larger EP
 bursting

Hi

Op 25-06-2021 om 23:19 schreef Wesley Cheng:
>
> On 6/25/2021 2:10 PM, Ferry Toth wrote:
>> Hi
>>
>> Op 23-06-2021 om 09:50 schreef Wesley Cheng:
>>> On 6/22/2021 3:12 PM, Ferry Toth wrote:
>>>> Hi
>>>>
>>>> Op 23-06-2021 om 00:00 schreef Wesley Cheng:
>>>>> On 6/22/2021 1:09 PM, Ferry Toth wrote:
>>>>>> Hi
>>>>>>
>>>>>> Op 22-06-2021 om 20:38 schreef Wesley Cheng:
>>>>>>> On 6/19/2021 5:40 AM, Ferry Toth wrote:
>>>>>>>> Hi
>>>>>>>>
>>>>>>>> Op 18-06-2021 om 00:25 schreef Wesley Cheng:
>>>>>>>>> Hi,
>>>>>>>>>
>>>>>>>>> On 6/17/2021 2:55 PM, Ferry Toth wrote:
>>>>>>>>>> Hi
>>>>>>>>>>
>>>>>>>>>> Op 17-06-2021 om 23:48 schreef Wesley Cheng:
>>>>>>>>>>> Hi,
>>>>>>>>>>>
>>>>>>>>>>> On 6/17/2021 2:01 PM, Ferry Toth wrote:
>>>>>>>>>>>> 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.
>>>>>>>>>>> I see...thanks Ferry! With your testing, are you writing to the
>>>>>>>>>>> device's
>>>>>>>>>>> internal storage (ie UFS, eMMC, etc...), or did you use a
>>>>>>>>>>> ramdisk as
>>>>>>>>>>> well?
>>>>>>>>>> In this case I just tested the EEM path using iperf3.
>>>>>>>>>>
>>>>>>>>> Got it.  I don't believe f_eem will use a high enough (if at all)
>>>>>>>>> bMaxBurst value to change the TXFIFO size.
>>>>>>>>>
>>>>>>>>>>> If not with a ramdisk, we might want to give that a try to avoid
>>>>>>>>>>> the
>>>>>>>>>>> storage path being the bottleneck.  You can use "dd" to create an
>>>>>>>>>>> empty
>>>>>>>>>>> file, and then just use that as the LUN's backing file.
>>>>>>>>>>>
>>>>>>>>>>> echo ramdisk.img >
>>>>>>>>>>> /sys/kernel/config/usb_gadget/g1/functions/mass_storage.0/lun.0/file
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>> Ah, why didn't I think of that. I have currently mass storage
>>>>>>>>>> setup
>>>>>>>>>> with
>>>>>>>>>> eMMC but it seems that is indeed the bottleneck.
>>>>>>>>>>
>>>>>>>> I created a 64MB disk following the instructions here
>>>>>>>> http://www.linux-usb.org/gadget/file_storage.html (that seems a
>>>>>>>> little
>>>>>>>> outdated, at least I can not start the first partition at sector 8,
>>>>>>>> but
>>>>>>>> minimum 2048), and added a test file on it.
>>>>>>>>
>>>>>>>> I then copy the file to /dev/shm prior to setting configfs
>>>>>>>> (composite
>>>>>>>> device gser/eem/mass_storage/uac2).
>>>>>>>>
>>>>>>>> journal shows:
>>>>>>>>
>>>>>>>> kernel: Mass Storage Function, version: 2009/09/11
>>>>>>>> kernel: LUN: removable file: (no medium)
>>>>>>>>
>>>>>>>> I don't know what that means, because I see the test file on the
>>>>>>>> ramdisk.
>>>>>>>>
>>>>>>>> Then I again used gnome disks to benchmark (read/write 10MB):
>>>>>>>>
>>>>>>>> With V10 on top v5.13.0-rc5:
>>>>>>>>
>>>>>>>> R/W speed = 35.6/35.8MB/s, access time 0.35ms
>>>>>>>>
>>>>>>>> With no patches on top v5.12.0:
>>>>>>>>
>>>>>>>> R/W speed = 35.7/36.1MB/s, access time 0.35ms
>>>>>>> Hi Ferry,
>>>>>>>
>>>>>>>> I see no speed difference (and it's about the same as with the eMMC
>>>>>>>> backed disk). But the patches are causing a new call trace
>>>>>>>>
>>>>>>> Would you happen to know what DWC3 controller revision the device is
>>>>>>> using?  The callstack print occurs, because it looks like it ran
>>>>>>> out of
>>>>>>> internal memory, although there should be logic present for making
>>>>>>> sure
>>>>>>> that at least there is enough room for 1 FIFO per endpoint.
>>>>>>> (possibly
>>>>>>> the logic/math depends on the controller revision)
>>>>> Hi Ferry,
>>>>>
>>>>>> Do you know where I could find that in a file on the device?
>>>>>>
>>>>> Maybe you can just dump the DWC3 registers?
>>>>> cat /sys/kernel/debug/usb/<controller name>/regdump
>>>> This isin host mode:
>>>>
>>>> ~# cat /sys/kernel/debug/usb/dwc3.0.auto/regdump
>>>> GSBUSCFG0 = 0x00000006
>>>> GSBUSCFG1 = 0x00000f00
>>>> GTXTHRCFG = 0x230a0000
>>>> GRXTHRCFG = 0x22800000
>>>> GCTL = 0x45801002
>>>> GEVTEN = 0x00000000
>>>> GSTS = 0x3e800001
>>>> GUCTL1 = 0x00000000
>>>> GSNPSID = 0x5533250a
>>>> GGPIO = 0x00000000
>>>> GUID = 0x00050d00
>>>> GUCTL = 0x0200ce00
>>>> GBUSERRADDR0 = 0x00000000
>>>> GBUSERRADDR1 = 0x00000000
>>> ...
>>> Hi Ferry,
>>>
>>> Great!  Thanks, that got me the information regarding the DWC3 revision
>>> you're using. (its version 2.50a)  I checked the DWC3 databook and looks
>>> like certain versions have some different math to calculate the TXFIFO
>>> size.  I have taken this into account and factored that in in the next
>>> revision.
>>>
>>> Is there a way you could collect the regdump in device mode w/ mass
>>> storage only composition after enumerating with the PC?  That would help
>>> confirm how the TXFIFO resizing logic is working on your platform.
>> Sorry for the wait. Yes I have serial console. So here is in device
>> mode, mass_storage only, enumerated but not mounted:
>>
>> GSBUSCFG0 = 0x00000006
>> GSBUSCFG1 = 0x00000f00
>> GTXTHRCFG = 0x230a0000
>> GRXTHRCFG = 0x02800000
>> GCTL = 0x45802002
>> GEVTEN = 0x00000000
> ...
> Hi Ferry,
>
> Thanks!  So does your board support SSUSB by any chance?  Based on the
> DSTS output, it seems that its currently operating in HSUSB mode.  I
> guess we'd expect higher tput values as well in general if we are in
> SSUSB mode.
Afaik indeed we have only HS.
> The resize logic would only happen if the device was in SSUSB, as SSUSB
> has endpoint bursting, which is the main incentive for the fifo resize.
>
> Thanks
> Wesley Cheng
>
>>> Thanks
>>> Wesley Cheng
>>>
>>>>> Was going to ask for the same to confirm the TXFIFO sizes from your
>>>>> results below :).
>>>>>
>>>>>> Otherwise, I'm hoping Andy will know?
>>>>>>
>>>>>>> Also, is there a way to use just a mass storage only composition?
>>>>>>> Based
>>>>>>> on the above observation, that probably means that the mass storage
>>>>>>> interface wasn't resized at all, because the configuration took up a
>>>>>>> lot
>>>>>>> of the internal FIFO space.
>>>>>> Sure, it's configured through configfs. With only mass_storage I have:
>>>>>>
>>>>>> With V10 on top v5.13.0-rc5:
>>>>>>
>>>>>> R/W speed = 41,6/39,3MB/s, access time 0.33ms
>>>>>>
>>>>>> With no patches on top v5.12.0:
>>>>>>
>>>>>> R/W speed = 41,1/38,7MB/s, access time 0.38ms
>>>>>>
>>>>> Thanks Ferry!  Could you collect the regdump, so I can confirm the two
>>>>> things mentioned?
>>>>>
>>>>> Thanks
>>>>> Wesley Cheng
>>>>>
>>>>>>> Thanks
>>>>>>> Wesley Cheng
>>>>>>>
>>>>>>>> kernel: using random self ethernet address
>>>>>>>> kernel: using random host ethernet address
>>>>>>>> kernel: Mass Storage Function, version: 2009/09/11
>>>>>>>> kernel: LUN: removable file: (no medium)
>>>>>>>> kernel: usb0: HOST MAC aa:bb:cc:dd:ee:f2
>>>>>>>> kernel: usb0: MAC aa:bb:cc:dd:ee:f1
>>>>>>>> kernel: IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
>>>>>>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>>>>>>> depth:115540359
>>>>>>>> kernel: ------------[ cut here ]------------
>>>>>>>> kernel: WARNING: CPU: 0 PID: 594 at
>>>>>>>> drivers/usb/gadget/udc/core.c:278
>>>>>>>> usb_ep_queue+0x75/0x80
>>>>>>>> kernel: Modules linked in: usb_f_uac2 u_audio usb_f_mass_storage
>>>>>>>> usb_f_eem u_ether usb_f_serial u_serial libcomposite rfcomm
>>>>>>>> iptable_nat
>>>>>>>> bnep snd_sof_nocodec spi_pxa2>
>>>>>>>> kernel: CPU: 0 PID: 594 Comm: irq/14-dwc3 Not tainted
>>>>>>>> 5.13.0-rc5-edison-acpi-standard #1
>>>>>>>> kernel: Hardware name: Intel Corporation Merrifield/BODEGA BAY,
>>>>>>>> BIOS 542
>>>>>>>> 2015.01.21:18.19.48
>>>>>>>> kernel: RIP: 0010:usb_ep_queue+0x75/0x80
>>>>>>>> kernel: Code: 01 73 e4 48 8b 05 fb 63 06 01 48 85 c0 74 12 48 8b
>>>>>>>> 78 08
>>>>>>>> 44 89 e9 4c 89 e2 48 89 ee e8 74 05 00 00 44 89 e8 5d 41 5c 41 5d c3
>>>>>>>> <0f> 0b 41 bd 94 ff ff ff >
>>>>>>>> kernel: RSP: 0000:ffff91eec083fc98 EFLAGS: 00010082
>>>>>>>> kernel: RAX: ffff8af20357d960 RBX: 0000000000000000 RCX:
>>>>>>>> ffff8af202f06400
>>>>>>>> kernel: RDX: 0000000000000a20 RSI: ffff8af208785780 RDI:
>>>>>>>> ffff8af202e9ae00
>>>>>>>> kernel: RBP: ffff8af202e9ae00 R08: 00000000000000c0 R09:
>>>>>>>> ffff8af208785780
>>>>>>>> kernel: R10: 00000000ffffe000 R11: 3fffffffffffffff R12:
>>>>>>>> ffff8af208785780
>>>>>>>> kernel: R13: 0000000000000000 R14: ffff8af202e9ae00 R15:
>>>>>>>> ffff8af203e26cc0
>>>>>>>> kernel: FS:  0000000000000000(0000) GS:ffff8af23e200000(0000)
>>>>>>>> knlGS:0000000000000000
>>>>>>>> kernel: CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>>>>> kernel: CR2: 000055e2c21f2100 CR3: 0000000003b38000 CR4:
>>>>>>>> 00000000001006f0
>>>>>>>> kernel: Call Trace:
>>>>>>>> kernel:  u_audio_start_playback+0x107/0x1a0 [u_audio]
>>>>>>>> kernel:  composite_setup+0x224/0x1ba0 [libcomposite]
>>>>>>>> kernel:  ? dwc3_gadget_ep_queue+0xf6/0x1a0
>>>>>>>> kernel:  ? usb_ep_queue+0x2a/0x80
>>>>>>>> kernel:  ? configfs_composite_setup+0x6b/0x90 [libcomposite]
>>>>>>>> kernel:  configfs_composite_setup+0x6b/0x90 [libcomposite]
>>>>>>>> kernel:  dwc3_ep0_interrupt+0x469/0xa80
>>>>>>>> kernel:  dwc3_thread_interrupt+0x8ee/0xf40
>>>>>>>> kernel:  ? __wake_up_common_lock+0x85/0xb0
>>>>>>>> kernel:  ? disable_irq_nosync+0x10/0x10
>>>>>>>> kernel:  irq_thread_fn+0x1b/0x60
>>>>>>>> kernel:  irq_thread+0xd6/0x170
>>>>>>>> kernel:  ? irq_thread_check_affinity+0x70/0x70
>>>>>>>> kernel:  ? irq_forced_thread_fn+0x70/0x70
>>>>>>>> kernel:  kthread+0x116/0x130
>>>>>>>> kernel:  ? kthread_create_worker_on_cpu+0x60/0x60
>>>>>>>> kernel:  ret_from_fork+0x22/0x30
>>>>>>>> kernel: ---[ end trace e5b9e28058c53584 ]---
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 000000003c32dcc5 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>>>>>>> depth:115540359
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000036ac129 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>>>>>>> depth:115540359
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000ad1b8c18 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000fbc71244 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>>>>>>> depth:115540359
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000fbc71244 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000ad1b8c18 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: Fifosize(2154) > RAM size(2022) ep5in
>>>>>>>> depth:115540359
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: configfs-gadget gadget: u_audio_start_playback:451 Error!
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 000000003c32dcc5 was not queued to
>>>>>>>> ep5in
>>>>>>>> kernel: dwc3 dwc3.0.auto: request 00000000b2512aa9 was not queued to
>>>>>>>> ep5in
>>>>>>>>
>>>>>>>> Removing uac2 from the config makes the call trace go away, but the
>>>>>>>> R/W
>>>>>>>> speed does not change.
>>>>>>>>
>>>>>>>>> :), not a problem...I've been working on getting the ideal set
>>>>>>>>> up for
>>>>>>>>> the performance profiling for awhile, so anything I can do to make
>>>>>>>>> sure
>>>>>>>>> we get some good results.
>>>>>>>>>
>>>>>>>>>> I'll try with a ramdisk and let you know.
>>>>>>>>>>
>>>>>>>>> Thanks again for the testing, Ferry.
>>>>>>>>>
>>>>>>>>> Thanks
>>>>>>>>> Wesley Cheng
>>>>>>>>>
>>>>>>>>>>> Thanks
>>>>>>>>>>> Wesley Cheng
>>>>>>>>>>>
>>>>>>>>>>>>> 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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