I am running Windows CE 5.0 with all available QFEs (including January 2008)
on a Samsung SMDK2410 CPU.
I have a problem with the USB OHCI (1.1) Host Controler:
-start device with a USB device attached to the single OHCI (USB 1.1) Host
Controller port
-occasionally (approximately 5-10 times out of 400 starts) the USB device is
not recognized
The problem occurs in the CHub::AttachDevice() function
(…\DRIVERS\USB\HCD\COMMON\cdevice.cpp):
-in the state machine in the
DEVICE_CONFIG_STATUS_SCHEDULING_GET_DEVICE_DESCRIPTOR_TEST step, I get an
USB_DEVICE_NOT_RESPONDING_ERROR (= 0x5).
-now the state machine goes back to the
DEVICE_CONFIG_STATUS_RESET_AND_ENABLE_PORT state and tries 2 more times
-ultimately after the 3 reties get the same error message the attach fails
The only way that I found to fix that problem is:
-physically unplugging the USB device and plugging it back in
-rebooting the system
Both solutions are not an option for me!
I also tried:
-more reties (10)
-timeout (100ms) before each retry
-powering off and repowering USB port between the reties
-making CHub::HubStatusChangeThread() belief the device was unplugged so do
a DetachDevice() and then (even after powering off and repowering the USB
port) let CHub::HubStatusChangeThread() do the AttachDevice() again
With all of these attempts the problem persisted: the device descriptor
could not be retrieved and the attach failed.
The file describes the cause and the fix of Windows CE 5.0's USB device
detection problem during power-up.
1. USB Device Detection Problem during Powering-Up
- Connect USB devices to EDB93xx's USB ports when the board is
powered-off.
- Power on EDB93xx.
- Wait until CE 5.0 is fully loaded.
- One or several USB devices are not detected by CE 5.0.
2. The Cause
In USB's Open Host Controller Interface (OHCI) Specification, in
Register HcRhDescriptorA (EP93xx address 0x80020048), Bits 24-31
are PowerOnToPowerGoodTime. This POTPGT byte specifies the duration
Host Controller Driver has to wait before accessing a powered-on port
of the Root Hub. It is implementation-specific. The unit of time
is 2 msec. The duration is calculated as POTPGT x 2msec.
EP93xx's default value of Register HcRhDescriptorA is 0x02001203.
The value of the POTPGT byte is 0x02. 2*2msec=4msec. It needs 4 msec
delay after the Host Controller has supplied power to the Root Hub.
The start-up sequence for EDB93xx's USB host controller should be
1. Host Controller supplies power to the Root Hub.
2. Delay 4 msec.
3. Set Host Controller to Operational state. Access USB ports. Start
to send SOF tokens...etc.
CE 5.0's USB driver doesn't implement the code to read the HcRhDescriptorA
register and deploy the required delay.
3. The Fix:
Add the 4-msec delay to CE's USB host driver then rebuild the platform.
Modify the filebr> WINCE500\PUBLIC\COMMON\OAK\DRIVERS\USB\HCD\OHCD2\chw.cpp
Please look at the code "//QQQQQ" below.
BOOL CHW::Initialize(void)
{
..................
InterruptDisable( m_dwSysIntr ); // Just to make sure this is really ours.
// Initialize Interrupt. When interrupt id # m_sysIntr is triggered,
// m_hUsbInterruptEvent will be signaled. Last 2 params must be NULL
if ( !InterruptInitialize( m_dwSysIntr, m_hUsbInterruptEvent, NULL, NULL) )
{
DEBUGMSG(ZONE_ERROR, (TEXT("-CHW::Initialize. Error on
InterruptInitializern")));
return FALSE;
}
// Apply power to all root hub ports, just like OHCI.
m_portBase->HcRhDescriptorA.NPS = 1;
m_portBase->HcRhStatus.reg= HcRegisters::HcRhStatus:PSC;
//QQQQQQQ Add 4msec delay that is required by Host Controller.
Sleep(4);
// Start up our IST - the parameter passed to the thread
// is unused for now
DEBUGCHK( m_hUsbInterruptThread == NULL &&
m_fUsbInterruptThreadClosing == FALSE );
m_hUsbInterruptThread = CreateThread( 0, 0, UsbInterruptThreadStub, this, 0,
NULL );
if ( m_hUsbInterruptThread == NULL ) {
DEBUGMSG(ZONE_ERROR, (TEXT("-CHW::Initialize. Error creating
ISTn")));
return FALSE;
}
CeSetThreadPriority( m_hUsbInterruptThread, g_IstThreadPriority );
......................
}
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