archive mirror
 help / color / mirror / Atom feed
From: Ferry Toth <>
To: Andy Shevchenko <>,
	Jack Pham <>
Cc: Thinh Nguyen <>,
	John Stultz <>,
	Amit Pundir <>, Ray Chi <>,
	Ferry Toth <>,
	Chunfeng Yun <>,
	Marek Szyprowski <>,
	Li Jun <>, Felipe Balbi <>,
	Greg Kroah-Hartman <>,, Wesley Cheng <>
Subject: Re: [RFT][PATCH] usb: dwc3: Decouple USB 2.0 L1 & L2 events
Date: Wed, 18 Aug 2021 21:48:18 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <YRzT4y87Nt8ICFJ/>

Op 18-08-2021 om 11:33 schreef Andy Shevchenko:
> On Tue, Aug 17, 2021 at 06:28:59PM -0700, Jack Pham wrote:
>> On Thu, Aug 12, 2021 at 01:26:35AM -0700, Jack Pham wrote:
>>> On DWC_usb3 revisions 3.00a and newer (including DWC_usb31 and
>>> DWC_usb32) the GUCTL1 register gained the DEV_DECOUPLE_L1L2_EVT
>>> field (bit 31) which when enabled allows the controller in device
>>> mode to treat USB 2.0 L1 LPM & L2 events separately.
>>> After commit d1d90dd27254 ("usb: dwc3: gadget: Enable suspend
>>> events") the controller will now receive events (and therefore
>>> interrupts) for every state change when entering/exiting either
>>> L1 or L2 states.  Since L1 is handled entirely by the hardware
>>> and requires no software intervention, there is no need to even
>>> enable these events and unnecessarily notify the gadget driver.
>>> Enable the aforementioned bit to help reduce the overall interrupt
>>> count for these L1 events that don't need to be handled while
>>> retaining the events for full L2 suspend/wakeup.
>> Hi folks in To:
>> I'd like to request if any of you could help test this patch on your
>> boards to help make sure it doesn't cause any regressions since I know
>> some of the recent dwc3 patches from Qualcomm have been found to break
>> other devices :(. So I'm hoping to avoid that even for a patch as
>> small as this.
>> Hoping this could be tried out on boards/SoCs such as db845c, hikey960,
>> Exynos, the Intel "lakes", etc.  Ideally this needs validation with a
>> high-speed connection to a USB 3.x host, which increases the chances
>> that USB 2.0 Link Power Management is supported.

Merrifield: We currently have 

Should I retest with this reverted?

>> The overall goal of this patch is to eliminate events generated for
>> L1 entry/exit, so we should see a slight reduction in interrupt counts
>> when checking `grep dwc3 /proc/interrupts` for comparable traffic.

I didn't compare interrupts

> Unfortunately I'm quite busy lately with more important stuff and I dunno if I
> will be able to test this in reasonable time. So, if Ferry volunteers, then we
> can cover Intel Merrifield platform as well.

Performance unchanged, no regressions found.
Tested-by: Ferry Toth <> # for Merrifield

  reply	other threads:[~2021-08-18 19:49 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  8:26 [PATCH] usb: dwc3: Decouple USB 2.0 L1 & L2 events Jack Pham
2021-08-18  1:28 ` [RFT][PATCH] " Jack Pham
2021-08-18  2:07   ` John Stultz
2021-08-18  7:52   ` Jun Li
2021-08-18  9:09   ` Amit Pundir
2021-08-18  9:33   ` Andy Shevchenko
2021-08-18 19:48     ` Ferry Toth [this message]
2021-08-19 12:26       ` Andy Shevchenko
2021-08-20 12:17       ` Jack Pham
2021-08-19  2:01   ` Thinh Nguyen
2021-08-18  5:08 ` [PATCH] " Felipe Balbi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).