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[PATCH] ehci: add think_time

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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: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
david-b@pacbell.net 2005-08-13 18:41:04 -07:00 committed by Greg Kroah-Hartman
parent 090ffa9d0e
commit e09711aef4
2 changed files with 30 additions and 9 deletions
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32
drivers/usb/core/hub.c
View file

@ -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;
}

7
drivers/usb/core/hub.h
View file

@ -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;