usb: Add support for txfifo threshold

CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the txfilltuning
field in the EHCI controller on reset.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Remy Bohmer <linux@bohmer.net>
Signed-off-by: Tom Warren <twarren@nvidia.com>

README

@@ -1125,6 +1125,9 @@ The following options need to be configured:
 				May be defined to allow interrupt polling
 				instead of using asynchronous interrupts
 
+		CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
+		txfilltuning field in the EHCI controller on reset.
+
 - USB Device:
 		Define the below if you wish to use the USB console.
 		Once firmware is rebuilt from a serial console issue the

drivers/usb/host/ehci-hcd.c

@@ -255,6 +255,13 @@ static int ehci_reset(void)
 #endif
 		ehci_writel(reg_ptr, tmp);
 	}
+
+#ifdef CONFIG_USB_EHCI_TXFIFO_THRESH
+	cmd = ehci_readl(&hcor->or_txfilltuning);
+	cmd &= ~TXFIFO_THRESH(0x3f);
+	cmd |= TXFIFO_THRESH(CONFIG_USB_EHCI_TXFIFO_THRESH);
+	ehci_writel(&hcor->or_txfilltuning, cmd);
+#endif
 out:
 	return ret;
 }

drivers/usb/host/ehci.h

@@ -80,7 +80,11 @@ struct ehci_hcor {
 	uint32_t or_ctrldssegment;
 	uint32_t or_periodiclistbase;
 	uint32_t or_asynclistaddr;
-	uint32_t _reserved_[9];
+	uint32_t _reserved_0_;
+	uint32_t or_burstsize;
+	uint32_t or_txfilltuning;
+#define TXFIFO_THRESH(p)		((p & 0x3f) << 16)
+	uint32_t _reserved_1_[6];
 	uint32_t or_configflag;
 #define FLAG_CF		(1 << 0)	/* true:  we'll support "high speed" */
 	uint32_t or_portsc[CONFIG_SYS_USB_EHCI_MAX_ROOT_PORTS];