[PATCH RFC] USB: Add HCD fastboot

Simon Arlott
2008-08-06T18:48:23Z

On 31/07/08 20:16, Alan Stern wrote:
>> > It's not entirely clear why usblp is blocking at all. Probably because
>> > it is waiting on the device semaphores for devices that are currently
>> > being probed -- the driver core won't allow two threads to probe the
>> > same device concurrently.
>>
>> Ok - so there could be some big improvements to be had by making the hcd
>> init happen as early as possible and the device initcalls later?
>
> Maybe. Perhaps a better approach would be to make the device driver
> initcalls before there are any devices for their probe routines to
> block on.

What about this?

The Makefiles become a bit messy, but by moving things around I get the
desired effect without splitting their initcalls.

[ 7.941890] Write protecting the kernel read-only data: 5656k
[ 5.437709] Write protecting the kernel read-only data: 5656k

2.5s faster, which is almost half the boot time.

Signed-off-by: Simon Arlott <simon@fire.lp0.eu>

---
drivers/Makefile | 13 ++++++++++---
drivers/usb/Makefile | 30 ++++++++++++++++++++----------
drivers/usb/core/Kconfig | 17 +++++++++++++++++
3 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/drivers/Makefile b/drivers/Makefile
index a280ab3..d68151f 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -33,7 +33,12 @@ obj-$(CONFIG_FB_INTEL) += video/intelfb/

obj-y += serial/
obj-$(CONFIG_PARPORT) += parport/
-obj-y += base/ block/ misc/ mfd/ net/ media/
+obj-y += base/ block/
+ifdef CONFIG_USB_FASTBOOT
+ obj-$(CONFIG_USB) += usb/
+ obj-$(CONFIG_PCI) += usb/
+endif
+obj-y += net/ media/
obj-$(CONFIG_NUBUS) += nubus/
obj-$(CONFIG_ATM) += atm/
obj-y += macintosh/
@@ -56,8 +61,10 @@ obj-$(CONFIG_MAC) += macintosh/
obj-$(CONFIG_ATA_OVER_ETH) += block/aoe/
obj-$(CONFIG_PARIDE) += block/paride/
obj-$(CONFIG_TC) += tc/
-obj-$(CONFIG_USB) += usb/
-obj-$(CONFIG_PCI) += usb/
+ifndef CONFIG_USB_FASTBOOT
+ obj-$(CONFIG_USB) += usb/
+ obj-$(CONFIG_PCI) += usb/
+endif
obj-$(CONFIG_USB_GADGET) += usb/gadget/
obj-$(CONFIG_SERIO) += input/serio/
obj-$(CONFIG_GAMEPORT) += input/gameport/
diff --git a/drivers/usb/Makefile b/drivers/usb/Makefile
index a419c42..35766a1 100644
--- a/drivers/usb/Makefile
+++ b/drivers/usb/Makefile
@@ -8,16 +8,22 @@ obj-$(CONFIG_USB) += core/

obj-$(CONFIG_USB_MON) += mon/

-obj-$(CONFIG_PCI) += host/
-obj-$(CONFIG_USB_EHCI_HCD) += host/
-obj-$(CONFIG_USB_ISP116X_HCD) += host/
-obj-$(CONFIG_USB_OHCI_HCD) += host/
-obj-$(CONFIG_USB_UHCI_HCD) += host/
-obj-$(CONFIG_USB_SL811_HCD) += host/
-obj-$(CONFIG_USB_U132_HCD) += host/
-obj-$(CONFIG_USB_R8A66597_HCD) += host/
-
-obj-$(CONFIG_USB_C67X00_HCD) += c67x00/
+tmp-y :=
+tmp-m :=
+tmp-$(CONFIG_PCI) += host/
+tmp-$(CONFIG_USB_EHCI_HCD) += host/
+tmp-$(CONFIG_USB_ISP116X_HCD) += host/
+tmp-$(CONFIG_USB_OHCI_HCD) += host/
+tmp-$(CONFIG_USB_UHCI_HCD) += host/
+tmp-$(CONFIG_USB_SL811_HCD) += host/
+tmp-$(CONFIG_USB_U132_HCD) += host/
+tmp-$(CONFIG_USB_R8A66597_HCD) += host/
+tmp-$(CONFIG_USB_C67X00_HCD) += c67x00/
+obj-m += $(tmp-m)
+
+ifndef CONFIG_USB_FASTBOOT
+ obj-y += $(tmp-y)
+endif

obj-$(CONFIG_USB_ACM) += class/
obj-$(CONFIG_USB_PRINTER) += class/
@@ -34,3 +40,7 @@ obj-$(CONFIG_USB) += misc/

obj-$(CONFIG_USB_ATM) += atm/
obj-$(CONFIG_USB_SPEEDTOUCH) += atm/
+
+ifdef CONFIG_USB_FASTBOOT
+ obj-y += $(tmp-y)
+endif
diff --git a/drivers/usb/core/Kconfig b/drivers/usb/core/Kconfig
index cc9f397..ea04a02 100644
--- a/drivers/usb/core/Kconfig
+++ b/drivers/usb/core/Kconfig
@@ -136,3 +136,20 @@ config USB_OTG_BLACKLIST_HUB
and software costs by not supporting external hubs. So
are "Emedded Hosts" that don't offer OTG support.

+
+config USB_FASTBOOT
+ bool "USB Fastboot (EXPERIMENTAL)"
+ depends on USB && EXPERIMENTAL
+ default n
+ help
+ If you say Y here, USB device driver initialisation will be
+ performed much earlier on boot followed by HCD initialisation.
+ Devices will then be initialised in the background USB hub
+ thread during the rest of the boot process.
+
+ Side effects of enabling this include IRQ assignments being
+ different from a normal bootup and the potential for USB and
+ non-USB devices to be ordered differently on each startup.
+ (i.e. usb sda, sata sdb vs. sata sda, usb sdb)
+
+ If you are unsure about this, say N here.
--
1.5.6.3

--
Simon Arlott