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From: Jack Pham <jackp@codeaurora.org>
To: Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
	John Stultz <john.stultz@linaro.org>,
	Amit Pundir <amit.pundir@linaro.org>, Ray Chi <raychi@google.com>,
	Ferry Toth <ftoth@exalondelft.nl>,
	Chunfeng Yun <chunfeng.yun@mediatek.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Li Jun <jun.li@nxp.com>
Cc: Felipe Balbi <balbi@kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-usb@vger.kernel.org, Wesley Cheng <wcheng@codeaurora.org>
Subject: Re: [RFT][PATCH] usb: dwc3: Decouple USB 2.0 L1 & L2 events
Date: Tue, 17 Aug 2021 18:28:59 -0700	[thread overview]
Message-ID: <20210818012859.GB30805@jackp-linux.qualcomm.com> (raw)
In-Reply-To: <20210812082635.12924-1-jackp@codeaurora.org>

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.

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.

Appreciate any feedback and help in testing!
Thanks,
Jack

> Signed-off-by: Jack Pham <jackp@codeaurora.org>
> ---
>  drivers/usb/dwc3/core.c | 9 +++++++++
>  drivers/usb/dwc3/core.h | 5 +++--
>  2 files changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index ba74ad7f6995..719dac228703 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1050,6 +1050,15 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		if (!DWC3_VER_IS_PRIOR(DWC3, 290A))
>  			reg |= DWC3_GUCTL1_DEV_L1_EXIT_BY_HW;
>  
> +		/*
> +		 * Decouple USB 2.0 L1 & L2 events which will allow for
> +		 * gadget driver to only receive U3/L2 suspend & wakeup
> +		 * events and prevent the more frequent L1 LPM transitions
> +		 * from interrupting the driver.
> +		 */
> +		if (!DWC3_VER_IS_PRIOR(DWC3, 300A))
> +			reg |= DWC3_GUCTL1_DEV_DECOUPLE_L1L2_EVT;
> +
>  		if (dwc->dis_tx_ipgap_linecheck_quirk)
>  			reg |= DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS;
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 5991766239ba..356b94a7ec70 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -256,9 +256,10 @@
>  #define DWC3_GUCTL_HSTINAUTORETRY	BIT(14)
>  
>  /* Global User Control 1 Register */
> -#define DWC3_GUCTL1_PARKMODE_DISABLE_SS	BIT(17)
> +#define DWC3_GUCTL1_DEV_DECOUPLE_L1L2_EVT	BIT(31)
>  #define DWC3_GUCTL1_TX_IPGAP_LINECHECK_DIS	BIT(28)
> -#define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW	BIT(24)
> +#define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW		BIT(24)
> +#define DWC3_GUCTL1_PARKMODE_DISABLE_SS		BIT(17)
>  
>  /* Global Status Register */
>  #define DWC3_GSTS_OTG_IP	BIT(10)
> -- 
> 2.24.0
> 

-- 
The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

  reply	other threads:[~2021-08-18  1:29 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12  8:26 [PATCH] " Jack Pham
2021-08-18  1:28 ` Jack Pham [this message]
2021-08-18  2:07   ` [RFT][PATCH] " 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
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

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