Commit e09711ae authored by David Brownell's avatar David Brownell Committed by Greg Kroah-Hartman
Browse files

[PATCH] ehci: add think_time 



This adds think_time to the usb_tt struct and sets it appropriately
(measured in ns); this can help us implement better split transaction
scheduling.

Signed-off-by: default avatarDan Streetman <ddstreet@ieee.org>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent 090ffa9d

drivers/usb/core/hub.c

+23 −9
Original line number Diff line number Diff line
@@ -627,19 +627,33 @@ static int hub_configure(struct usb_hub *hub, 
			break;

	}



	/* Note 8 FS bit times == (8 bits / 12000000 bps) ~= 666ns */

	switch (hub->descriptor->wHubCharacteristics & HUB_CHAR_TTTT) {

		case 0x00:

			if (hdev->descriptor.bDeviceProtocol != 0)

				dev_dbg(hub_dev, "TT requires at most 8 FS bit times\n");

		case HUB_TTTT_8_BITS:

			if (hdev->descriptor.bDeviceProtocol != 0) {

				hub->tt.think_time = 666;

				dev_dbg(hub_dev, "TT requires at most %d "

						"FS bit times (%d ns)\n",

					8, hub->tt.think_time);

			}

			break;

		case 0x20:

			dev_dbg(hub_dev, "TT requires at most 16 FS bit times\n");

		case HUB_TTTT_16_BITS:

			hub->tt.think_time = 666 * 2;

			dev_dbg(hub_dev, "TT requires at most %d "

					"FS bit times (%d ns)\n",

				16, hub->tt.think_time);

			break;

		case 0x40:

			dev_dbg(hub_dev, "TT requires at most 24 FS bit times\n");

		case HUB_TTTT_24_BITS:

			hub->tt.think_time = 666 * 3;

			dev_dbg(hub_dev, "TT requires at most %d "

					"FS bit times (%d ns)\n",

				24, hub->tt.think_time);

			break;

		case 0x60:

			dev_dbg(hub_dev, "TT requires at most 32 FS bit times\n");

		case HUB_TTTT_32_BITS:

			hub->tt.think_time = 666 * 4;

			dev_dbg(hub_dev, "TT requires at most %d "

					"FS bit times (%d ns)\n",

				32, hub->tt.think_time);

			break;

	}

drivers/usb/core/hub.h

+7 −0
Original line number Diff line number Diff line
@@ -157,6 +157,12 @@ enum hub_led_mode { 


struct usb_device;



/* Transaction Translator Think Times, in bits */

#define HUB_TTTT_8_BITS		0x00

#define HUB_TTTT_16_BITS	0x20

#define HUB_TTTT_24_BITS	0x40

#define HUB_TTTT_32_BITS	0x60



/*

 * As of USB 2.0, full/low speed devices are segregated into trees.

 * One type grows from USB 1.1 host controllers (OHCI, UHCI etc).
@@ -170,6 +176,7 @@ struct usb_device; 
struct usb_tt {

	struct usb_device	*hub;	/* upstream highspeed hub */

	int			multi;	/* true means one TT per port */

	unsigned		think_time;	/* think time in ns */



	/* for control/bulk error recovery (CLEAR_TT_BUFFER) */

	spinlock_t		lock;