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 00:30:44 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Krishna Kurapati <quic_kriskura@...cinc.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 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