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authordavid-b@pacbell.net <david-b@pacbell.net>2005-08-13 18:41:04 -0700
committerGreg Kroah-Hartman <gregkh@suse.de>2005-09-08 16:28:35 -0700
commite09711aef4180002241c7f2eab37390ddf40d6a0 (patch)
tree9a537e417df8b8ab0d8e121f6a3e596898ec8ec0 /drivers/usb
parent090ffa9d0e904e1ed0f86c84dcf20684a8ac1a5a (diff)
[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: Dan Streetman <ddstreet@ieee.org> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb')
-rw-r--r--drivers/usb/core/hub.c32
-rw-r--r--drivers/usb/core/hub.h7
2 files changed, 30 insertions, 9 deletions
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 9f54e8330f7..758c7f0ed15 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -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;
}
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 53bf5649621..e7fa9b5a521 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -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;