RE: [linux-usb-devel] EHCI - OTG Transceiver (ULPI ) Issues

[Li Yang-r58472]

 -Original Message-
 From: [EMAIL PROTECTED]
 [mailto:[EMAIL PROTECTED] On Behalf Of rakesh kn
 Sent: Tuesday, April 04, 2006 12:12 PM
 To: linux-usb-devel@lists.sourceforge.net
 Subject: [linux-usb-devel] EHCI - OTG Transceiver (ULPI ) Issues
 
 H i
 
 ARC controller Core is having the ULPI interface as its
 Transceiver. I have a some deviations in USBSTS, PORTSCx,OTGSC
 registers for programming ULPI transceiver select, clocking etc.
 
Like USB controller in MPC8349E.
 Can u provide some help on general issues, on how the transceiver must
 be approached while programming.
 
 a) During a SUSPEND of the controller.. should i be putting the
 transceiver in low power mode. by disabling its clock.
That depends on how power sensitive your device is.  In MPC8349, set the 
controller to suspend mode is enough.
 
 b) Also Can u provide some light on isses that have to be taken in to
 account when i have a transceiver ULPI for my ARC controller ( I WOULD
 LIKE TO ADD THAT IT IS NOT AN EXTERNAL TRANSCEIVER CHIP. THE ULPI
 TRANSCEIVER IS INTEGERATED IN TO THE ARC CONTROLLER.)
Whether or not the controller and transceiver are physically separated, it's 
easy to divide them logically.  You can put management to OTGSC register in a 
separate OTG driver.
 
 Please comment on these issues. This would be of great help

Regards,
Leo


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Re: [linux-usb-devel] EHCI - OTG Transceiver (ULPI ) Issues

[Li Yang-r58472]

 -Original Message-
 From: rakesh kn [mailto:[EMAIL PROTECTED]
 Sent: Tuesday, April 04, 2006 3:59 PM
 To: Li Yang-r58472
 Subject: Re: [linux-usb-devel] EHCI - OTG Transceiver (ULPI ) Issues
 
 Hi Leo,
 Thanks for ur reply. It was informative.
 
 If u have experience in developing EHCI-OTG driver in linux,
 Can u please comment on the following issues.
 
   I am working on linux-2.6.10 for some unavoidable reasons.
   I am writing the host controller driver (Ehci) for ARC-OTG HS
 controller, with the
  ULPI interface.
If you are only interested in host controller driver, there is no need to care 
about the transceiver and OTG related issues.  OTG support is far more than the 
changes you indicated below.  You need a separate transceiver driver to handle 
OTGSC interrupts and OTG state change.  And that is not needed when the 
controller is used as host only.

For ARC SoC USB controller host support, there should be several 
implementations for reference, most of which are for MPC8349E.  I have posted 
one on the list before and there is also one implemented by Montavista in 
current -mm tree.

Ps: I'm no authority on linux usb.  But I'd like to share my experience.
 
 1) I have taken in to consideration the framework of OMAP , and added
 the additions
 that have been made in to ohci-hcd structure to support OTG on OMAP. I
 took those and added them to the present ehci-hcd  structure.
 
 2) Also i had to modify the ehci-hub.c to add the flag CONFIG_USB_OTG
 and defined the following functions
  a) ehci_start_port_reset
  Also in function ehci_hub_control , in the case of
 SetPort Feature , if we are suspening the port ... i.e
 USB_PORT_FEAT_SUSPEND ,
 i have added the conditional inclusion of start_hnp(), which is the
 same they did for ohci-hub.c., where the port is suspended.
 
 3) Also please tell where else should the host controller be dependent
 on issues with transceiver.
 
 
 Thanks
 Rak



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