usb: gadget: composite: Set recommended BESL values

Set the recommended BESL deep and baseline values based on the gadget's
configuration parameters to the extended BOS descriptor. This feature
helps to optimize power savings by maximizing the opportunity for longer
L1 residency time.

Signed-off-by: Thinh Nguyen <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

Author: Thinh Nguyen

drivers/usb/gadget/composite.c

@@ -612,13 +612,37 @@ static int bos_desc(struct usb_composite_dev *cdev)
 	struct usb_ext_cap_descriptor	*usb_ext;
 	struct usb_dcd_config_params	dcd_config_params;
 	struct usb_bos_descriptor	*bos = cdev->req->buf;
+	unsigned int			besl = 0;
 
 	bos->bLength = USB_DT_BOS_SIZE;
 	bos->bDescriptorType = USB_DT_BOS;
 
 	bos->wTotalLength = cpu_to_le16(USB_DT_BOS_SIZE);
 	bos->bNumDeviceCaps = 0;
 
+	/* Get Controller configuration */
+	if (cdev->gadget->ops->get_config_params) {
+		cdev->gadget->ops->get_config_params(cdev->gadget,
+						     &dcd_config_params);
+	} else {
+		dcd_config_params.besl_baseline =
+			USB_DEFAULT_BESL_UNSPECIFIED;
+		dcd_config_params.besl_deep =
+			USB_DEFAULT_BESL_UNSPECIFIED;
+		dcd_config_params.bU1devExitLat =
+			USB_DEFAULT_U1_DEV_EXIT_LAT;
+		dcd_config_params.bU2DevExitLat =
+			cpu_to_le16(USB_DEFAULT_U2_DEV_EXIT_LAT);
+	}
+
+	if (dcd_config_params.besl_baseline != USB_DEFAULT_BESL_UNSPECIFIED)
+		besl = USB_BESL_BASELINE_VALID |
+			USB_SET_BESL_BASELINE(dcd_config_params.besl_baseline);
+
+	if (dcd_config_params.besl_deep != USB_DEFAULT_BESL_UNSPECIFIED)
+		besl |= USB_BESL_DEEP_VALID |
+			USB_SET_BESL_DEEP(dcd_config_params.besl_deep);
+
 	/*
 	 * A SuperSpeed device shall include the USB2.0 extension descriptor
 	 * and shall support LPM when operating in USB2.0 HS mode.
@@ -629,7 +653,8 @@ static int bos_desc(struct usb_composite_dev *cdev)
 	usb_ext->bLength = USB_DT_USB_EXT_CAP_SIZE;
 	usb_ext->bDescriptorType = USB_DT_DEVICE_CAPABILITY;
 	usb_ext->bDevCapabilityType = USB_CAP_TYPE_EXT;
-	usb_ext->bmAttributes = cpu_to_le32(USB_LPM_SUPPORT | USB_BESL_SUPPORT);
+	usb_ext->bmAttributes = cpu_to_le32(USB_LPM_SUPPORT |
+					    USB_BESL_SUPPORT | besl);
 
 	/*
 	 * The Superspeed USB Capability descriptor shall be implemented by all
@@ -650,17 +675,6 @@ static int bos_desc(struct usb_composite_dev *cdev)
 						      USB_HIGH_SPEED_OPERATION |
 						      USB_5GBPS_OPERATION);
 		ss_cap->bFunctionalitySupport = USB_LOW_SPEED_OPERATION;
-
-		/* Get Controller configuration */
-		if (cdev->gadget->ops->get_config_params) {
-			cdev->gadget->ops->get_config_params(cdev->gadget,
-				&dcd_config_params);
-		} else {
-			dcd_config_params.bU1devExitLat =
-				USB_DEFAULT_U1_DEV_EXIT_LAT;
-			dcd_config_params.bU2DevExitLat =
-				cpu_to_le16(USB_DEFAULT_U2_DEV_EXIT_LAT);
-		}
 		ss_cap->bU1devExitLat = dcd_config_params.bU1devExitLat;
 		ss_cap->bU2DevExitLat = dcd_config_params.bU2DevExitLat;
 	}

include/uapi/linux/usb/ch9.h

@@ -894,6 +894,8 @@ struct usb_ext_cap_descriptor {		/* Link Power Management */
 #define USB_BESL_SUPPORT		(1 << 2)	/* supports BESL */
 #define USB_BESL_BASELINE_VALID		(1 << 3)	/* Baseline BESL valid*/
 #define USB_BESL_DEEP_VALID		(1 << 4)	/* Deep BESL valid */
+#define USB_SET_BESL_BASELINE(p)	(((p) & 0xf) << 8)
+#define USB_SET_BESL_DEEP(p)		(((p) & 0xf) << 12)
 #define USB_GET_BESL_BASELINE(p)	(((p) & (0xf << 8)) >> 8)
 #define USB_GET_BESL_DEEP(p)		(((p) & (0xf << 12)) >> 12)
 } __attribute__((packed));