linux-kernel - Re: [PATCH v3 1/2] usb: dwc3: core: add support for disabling High-speed park mode

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Date:   Wed, 19 Apr 2023 00:20:27 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Stanley Chang <stanley_chang@...ltek.com>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Felipe Balbi <balbi@...nel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 1/2] usb: dwc3: core: add support for disabling
 High-speed park mode

On Thu, Apr 13, 2023, Stanley Chang wrote:
> Setting the PARKMODE_DISABLE_HS bit in the DWC3_USB3_GUCTL1.
> When this bit is set to '1' all HS bus instances in park mode are disabled
> 
> For some USB wifi devices, if enable this feature it will reduce the
> performance. Therefore, add an option for disabling HS park mode by
> device-tree.
> 
> In Synopsys's dwc3 data book:
> In a few high speed devices when an IN request is sent within 900ns of the
> ACK of the previous packet, these devices send a NAK. When connected to
> these devices, if required, the software can disable the park mode if you
> see performance drop in your system. When park mode is disabled,
> pipelining of multiple packet is disabled and instead one packet at a time
> is requested by the scheduler. This allows up to 12 NAKs in a micro-frame
> and improves performance of these slow devices.
> 
> Signed-off-by: Stanley Chang <stanley_chang@...ltek.com>
> ---
> v2 to v3 change:
> 1. Add the comment message.
> 2. cc the right maintainers.
> ---
>  drivers/usb/dwc3/core.c | 5 +++++
>  drivers/usb/dwc3/core.h | 4 ++++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 476b63618511..8fbc92a5f2cb 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1233,6 +1233,9 @@ static int dwc3_core_init(struct dwc3 *dwc)
>  		if (dwc->parkmode_disable_ss_quirk)
>  			reg |= DWC3_GUCTL1_PARKMODE_DISABLE_SS;
>  
> +		if (dwc->parkmode_disable_hs_quirk)
> +			reg |= DWC3_GUCTL1_PARKMODE_DISABLE_HS;
> +
>  		if (DWC3_VER_IS_WITHIN(DWC3, 290A, ANY) &&
>  		    (dwc->maximum_speed == USB_SPEED_HIGH ||
>  		     dwc->maximum_speed == USB_SPEED_FULL))
> @@ -1555,6 +1558,8 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>  				"snps,resume-hs-terminations");
>  	dwc->parkmode_disable_ss_quirk = device_property_read_bool(dev,
>  				"snps,parkmode-disable-ss-quirk");
> +	dwc->parkmode_disable_hs_quirk = device_property_read_bool(dev,
> +				"snps,parkmode-disable-hs-quirk");
>  	dwc->gfladj_refclk_lpm_sel = device_property_read_bool(dev,
>  				"snps,gfladj-refclk-lpm-sel-quirk");
>  
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 4743e918dcaf..30907ffcb3ec 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -263,6 +263,7 @@
>  #define DWC3_GUCTL1_DEV_FORCE_20_CLK_FOR_30_CLK	BIT(26)
>  #define DWC3_GUCTL1_DEV_L1_EXIT_BY_HW		BIT(24)
>  #define DWC3_GUCTL1_PARKMODE_DISABLE_SS		BIT(17)
> +#define DWC3_GUCTL1_PARKMODE_DISABLE_HS		BIT(16)
>  #define DWC3_GUCTL1_RESUME_OPMODE_HS_HOST	BIT(10)
>  
>  /* Global Status Register */
> @@ -1102,6 +1103,8 @@ struct dwc3_scratchpad_array {
>   *			generation after resume from suspend.
>   * @parkmode_disable_ss_quirk: set if we need to disable all SuperSpeed
>   *			instances in park mode.
> + * @parkmode_disable_hs_quirk: set if we need to disable all HishSpeed
> + *			instances in park mode.
>   * @tx_de_emphasis_quirk: set if we enable Tx de-emphasis quirk
>   * @tx_de_emphasis: Tx de-emphasis value
>   *	0	- -6dB de-emphasis
> @@ -1318,6 +1321,7 @@ struct dwc3 {
>  	unsigned		dis_tx_ipgap_linecheck_quirk:1;
>  	unsigned		resume_hs_terminations:1;
>  	unsigned		parkmode_disable_ss_quirk:1;
> +	unsigned		parkmode_disable_hs_quirk:1;
>  	unsigned		gfladj_refclk_lpm_sel:1;
>  
>  	unsigned		tx_de_emphasis_quirk:1;
> -- 
> 2.34.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>

Thanks,
Thinh