Resetting USB HC .. During kernel boot

Resetting USB HC .. During kernel boot

[Prabhu Chawandi]

Hi All,

   I want to reset the USB HC  while the booting is happening. I have
the register details and functionality with me, but not sure which
part of the code to insert this segment.

please advice me ...

thanks,
Prabhu

Re: Resetting USB HC .. During kernel boot

[Alan Stern]

On Thu, 2 Sep 2010, Prabhu Chawandi wrote:

> Hi All,
> 
>    I want to reset the USB HC  while the booting is happening. I have
> the register details and functionality with me, but not sure which
> part of the code to insert this segment.
> 
> please advice me ...

Why do you want to do this?

Anyway, it depends on what type of host controller you're talking 
about.  UHCI controllers are already reset during boot.  The same is 
true for PCI-based EHCI and OHCI controllers (except on certain PA-RISC 
systems).

I haven't checked the various non-PCI controllers.

Alan Stern

Re: Resetting USB HC .. During kernel boot

[Prabhu Chawandi]

Hi Alan,

  I am working on a board, where USB controller is on chip. and this
has both UHC and EHC.  I have to reset these during the boot up.
Bootloader does not reset it before handing over control to kernel, I
am facing crash. So I am planning to reset here in kernel.

Can you help to locate the file, where this part of the code can be inserted.

Thanks in advance,
Prabhu


On Thu, Sep 2, 2010 at 7:56 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Thu, 2 Sep 2010, Prabhu Chawandi wrote:
>
>> Hi All,
>>
>>    I want to reset the USB HC  while the booting is happening. I have
>> the register details and functionality with me, but not sure which
>> part of the code to insert this segment.
>>
>> please advice me ...
>
> Why do you want to do this?
>
> Anyway, it depends on what type of host controller you're talking
> about.  UHCI controllers are already reset during boot.  The same is
> true for PCI-based EHCI and OHCI controllers (except on certain PA-RISC
> systems).
>
> I haven't checked the various non-PCI controllers.
>
> Alan Stern
>
>

Re: Resetting USB HC .. During kernel boot

[Alan Stern]

On Fri, 3 Sep 2010, Prabhu Chawandi wrote:

> Hi Alan,
> 
>   I am working on a board, where USB controller is on chip. and this
> has both UHC and EHC.  I have to reset these during the boot up.
> Bootloader does not reset it before handing over control to kernel, I
> am facing crash. So I am planning to reset here in kernel.
> 
> Can you help to locate the file, where this part of the code can be inserted.

No.  All I can tell you is that it will be somewhere in the 
platform-specific code for your board, i.e., somewhere under arch/.

Alan Stern