-----Original Message----- From: Andi Kleen [mailto:ak@suse.de] Sent: Wednesday, December 06, 2006 12:59 PM
I haven't looked how the other usb_debug works -- if it's polled too then it wouldn't have much advantage.
Need to verify if the two sides of debug cable are identical.
And it would be good if the late usb_debug still wouldn't rely on interrupts.
Yes, esp. when usb can not get irq assigned correctly.
YH
On Wed, Dec 06, 2006 at 01:08:14PM -0800, Lu, Yinghai wrote:
-----Original Message----- From: Andi Kleen [mailto:ak@suse.de] Sent: Wednesday, December 06, 2006 12:59 PM
I haven't looked how the other usb_debug works -- if it's polled too then it wouldn't have much advantage.
Need to verify if the two sides of debug cable are identical.
I got my device yesterday and after a small plugfest I can confirm that only one end of the device enumerates when connected to an ICH7 EHCI driven by 2.6.19.
--8<-- Bus 001 Device 027: ID 0525:127a Netchip Technology, Inc. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x0525 Netchip Technology, Inc. idProduct 0x127a bcdDevice 1.01 iManufacturer 1 NetChip iProduct 2 NetChip TurboCONNECT 2.0 iSerial 3 1 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xc0 Self Powered MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Debug descriptor: bLength 4 bDescriptorType 10 bDebugInEndpoint 0x82 bDebugOutEndpoint 0x01 -->8--
The device is in fact not self-powered.
My theory is that the same set of descriptors are used for both ends, but one end has been locked to address 127 in order to work with simpler debug port drivers that assume it will be there.
I guess that the self-powered error is also to simplify life for debug port drivers. IIRC most if not all USB power management concerns are noops for debug ports.
//Peter
On Thu, 7 Dec 2006, Peter Stuge wrote:
On Wed, Dec 06, 2006 at 01:08:14PM -0800, Lu, Yinghai wrote:
-----Original Message----- From: Andi Kleen [mailto:ak@suse.de] Sent: Wednesday, December 06, 2006 12:59 PM
I haven't looked how the other usb_debug works -- if it's polled too then it wouldn't have much advantage.
Need to verify if the two sides of debug cable are identical.
In fact they are not. They are almost identical but not exactly the same.
I got my device yesterday and after a small plugfest I can confirm that only one end of the device enumerates when connected to an ICH7 EHCI driven by 2.6.19.
This is incorrect. Both sides will enumerate. In fact, both sides will enumerate even at full speed (when plugged in to a UHCI controller instead of EHCI).
The difference is that the device will accept power only from one side -- let's call it the A side (the side to the right when you have the PLX logo facing you).
The device is bus-powered, so nothing will happen if the A side isn't plugged in. But if it is then both the A and B sides will enumerate. Their descriptors are almost the same; only the serial numbers are different. The A side's serial number string is "1", and the B side's serial number string is "0". Oddly enough, both sides use the same string index number for the descriptor (3).
Bus 001 Device 027: ID 0525:127a Netchip Technology, Inc. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x0525 Netchip Technology, Inc. idProduct 0x127a bcdDevice 1.01 iManufacturer 1 NetChip iProduct 2 NetChip TurboCONNECT 2.0 iSerial 3 1
...
The device is in fact not self-powered.
My theory is that the same set of descriptors are used for both ends, but one end has been locked to address 127 in order to work with simpler debug port drivers that assume it will be there.
No, you are wrong. The device will accept any address on either side.
I guess that the self-powered error is also to simplify life for debug port drivers. IIRC most if not all USB power management concerns are noops for debug ports.
I don't see how it would make life any simpler, but the device certainly does lie about its power source.
Alan Stern
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Alan Stern -
Lu, Yinghai -
Peter Stuge