linux-kernel - Re: [PATCH v2] usb: dwc3: core: set force_gen1 bit in USB31 devices if max speed is SS

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Date:   Wed, 17 May 2023 08:55:44 +0530
From:   Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "quic_ppratap@...cinc.com" <quic_ppratap@...cinc.com>,
        "quic_wcheng@...cinc.com" <quic_wcheng@...cinc.com>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>,
        "quic_ugoswami@...cinc.com" <quic_ugoswami@...cinc.com>
Subject: Re: [PATCH v2] usb: dwc3: core: set force_gen1 bit in USB31 devices
 if max speed is SS



On 5/17/2023 6:00 AM, Thinh Nguyen wrote:
> On Wed, May 17, 2023, Thinh Nguyen wrote:
>> On Sun, May 14, 2023, Krishna Kurapati wrote:
>>> Currently for dwc3_usb31 controller, if maximum_speed is limited to
>>> super-speed in DT, then device mode is limited to SS, but host mode
>>> still works in SSP.
>>>
>>> The documentation for max-speed property is as follows:
>>>
>>> "Tells USB controllers we want to work up to a certain speed.
>>> Incase  this isn't passed via DT, USB controllers should default to
>>> their maximum HW capability."
>>>
>>> It doesn't specify that the property is only for device mode.
>>> There are cases where we need to limit the host's maximum speed to
>>> SuperSpeed only. Use this property for host mode to contrain host's
>>> speed to SuperSpeed.
>>>
>>> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
>>> ---
>>> Link to v1: https://urldefense.com/v3/__https://lore.kernel.org/all/20230512170107.18821-1-quic_kriskura@quicinc.com/__;!!A4F2R9G_pg!dCg_3WK2oNXNb6d0a_VuyjkeeZJTU1aY4dik6g35XB7mtG7EJeR1uPMfxFja49OfXp7Yhsg1yqjnylCYYEg7YCAhqfAZ0Q$
>>>
>>> Discussion regarding the same at:
>>> https://urldefense.com/v3/__https://lore.kernel.org/all/e465c69c-3a9d-cbdb-d44e-96b99cfa1a92@quicinc.com/__;!!A4F2R9G_pg!dCg_3WK2oNXNb6d0a_VuyjkeeZJTU1aY4dik6g35XB7mtG7EJeR1uPMfxFja49OfXp7Yhsg1yqjnylCYYEg7YCDRLUrJWg$
>>>
>>>   drivers/usb/dwc3/core.c | 8 ++++++++
>>>   drivers/usb/dwc3/core.h | 5 +++++
>>>   2 files changed, 13 insertions(+)
>>>
>>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> index 278cd1c33841..33bc72595e74 100644
>>> --- a/drivers/usb/dwc3/core.c
>>> +++ b/drivers/usb/dwc3/core.c
>>> @@ -1262,6 +1262,14 @@ static int dwc3_core_init(struct dwc3 *dwc)
>>>   		}
>>>   	}
>>>   
>>> +	if ((hw_mode != DWC3_GHWPARAMS0_MODE_GADGET) &&
>>> +	    (DWC3_IP_IS(DWC31)) &&
>>> +	    (dwc->maximum_speed == USB_SPEED_SUPER)) {
>>> +		reg = dwc3_readl(dwc->regs, DWC3_LLUCTL);
>>> +		reg |= DWC3_LLUCTL_FORCE_GEN1;
>>> +		dwc3_writel(dwc->regs, DWC3_LLUCTL, reg);
>>> +	}
>>> +
>>
>> Perhaps this should be done for every usb3 port rather than just the
>> port_0. This patch can go after your multi-port series is added to
>> Greg's branch where you can check for number of usb3 ports.
>>
> 
> Can you also add dwc_usb32 settings? It should look something like this:
> 
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 0beaab932e7d..4bd2564aa163 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1262,6 +1262,40 @@ static int dwc3_core_init(struct dwc3 *dwc)
>   		}
>   	}
>   
> +	if (hw_mode != DWC3_GHWPARAMS0_MODE_GADGET) {
> +		int i;
> +
> +		if (DWC3_IP_IS(DWC31) &&
> +		    dwc->maximum_speed == USB_SPEED_SUPER) {
> +			for (i = 0; i < dwc->num_usb3_ports; i++) {
> +				reg = dwc3_readl(dwc->regs, DWC3_LLUCTL(i));
> +				reg |= DWC3_LLUCTL_FORCE_GEN1;
> +				dwc3_writel(dwc->regs, DWC3_LLUCTL(i), reg);
> +			}
> +		}
> +
> +		if (DWC3_IP_IS(DWC32) &&
> +		    dwc->max_ssp_rate != USB_SSP_GEN_2x2) {
> +			int lsr_speed = -EINVAL;
> +
> +			if (dwc->maximum_speed == USB_SPEED_SUPER)
> +				lsr_speed = DWC3_LCSR_GEN_1x1;
> +			else if (dwc->max_ssp_rate == USB_SSP_GEN_2x1)
> +				lsr_speed = DWC3_LCSR_GEN_2x1;
> +			else if (dwc->max_ssp_rate == USB_SSP_GEN_1x2)
> +				lsr_speed = DWC3_LCSR_GEN_1x2;
> +
> +			if (lsr_speed != -EINVAL) {
> +				for (i = 0; i < dwc->num_usb3_ports; i++) {
> +					reg = dwc3_readl(dwc->regs, DWC3_LCSR_USB32CTL(i));
> +					reg &= ~DWC3_LCSR_USB32CTL_SPEED_MASK;
> +					reg |= lsr_speed;
> +					dwc3_writel(dwc->regs, DWC3_LCSR_USB32CTL(i), reg);
> +				}
> +			}
> +		}
> +	}
> +
>   	return 0;
>   
>   err_power_off_phy:
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index d56457c02996..415e0215fe00 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -170,6 +170,9 @@
>   #define DWC3_OEVTEN		0xcc0C
>   #define DWC3_OSTS		0xcc10
>   
> +#define DWC3_LLUCTL(n)		(0xd024 + ((n) * 0x80))
> +#define DWC3_LCSR_USB32CTL(n)	(0xd07c + ((n) * 0x80))
> +
>   /* Bit fields */
>   
>   /* Global SoC Bus Configuration INCRx Register 0 */
> @@ -653,6 +656,16 @@
>   #define DWC3_OSTS_VBUSVLD		BIT(1)
>   #define DWC3_OSTS_CONIDSTS		BIT(0)
>   
> +/* LLUCTL Register */
> +#define DWC3_LLUCTL_FORCE_GEN1		BIT(10)
> +
> +/* LCSR_USB32CTL Register */
> +#define DWC3_LCSR_USB32CTL_SPEED_MASK	0x3
> +#define DWC3_LCSR_GEN_1x1		0
> +#define DWC3_LCSR_GEN_1x2		1
> +#define DWC3_LCSR_GEN_2x1		2
> +#define DWC3_LCSR_GEN_2x2		3
> +
>   /* Structures */
>   
>   struct dwc3_trb;
> 
>   --
> 
>   Thanks,
>   Thinh


Hi Thinh,

  Sure, will split it up into two patches and send as a series. But 
might need your help in testing SSP patch as I don't have any device 
supporting ssp.

Regards,
Krishna,