lkml.org 
[lkml]   [2013]   [Jul]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 14/16] usb: musb: dsps: add MUSB_DEVCTL_SESSION back after removal
On 07/29/2013 07:26 PM, Bin Liu wrote:
> Sebastian,

Hi Bin,

> I did not say AM335xEVM is not able to run OTG mode. The problem is in
> OTG mode the SESSION bit will be cleared once the device is unplugged,
> then there is no way the SESSION bit will come back in the current
> mainline kernel.

Yes, you did.

>
> The TI 3.2 kernel works around this OTG issue by toggling the SESSION
> bit in b_idle handling in otg_timer(). The workaround makes most users
> happy but it causes VBUS voltage pulsing. That is why I said I don't
> know an ideal solution without a ID pin interrupt support.

Now I understand more pieces of the puzzle. And the missing ID pin
support is Am335x-evm specific since other am335x board may wire up
that pin.
But you say there is no way that the phy or anything else could help to
avoid that pulsing.

> I think you looked at a wrong file, maybe a wrong branch. Please check
> [1], which defines
>
> 2644 * mode[0:3] = USB0PORT's mode
> 2645 * mode[4:7] = USB1PORT's mode
> 2646 * AM335X beta EVM has USB0 in OTG mode and USB1 in host mode.
> 2647 */
> 2648 .mode = (MUSB_HOST << 4) | MUSB_OTG,

Oh it is a long way. So looked into the wrong branch.

>> I agree that without that try_idle part things keep working but it
>> seems, that it is also called in the other tree.
>>
>
> Then because AM335xEVM USB1 port does not call *try_idle() in this 3.2
> kernel, its SESSION bit is always set.
>
> But I don't have a clear idea how to solve this in the mainline kernel
> since is_otg_enabled() has been cleaned.

So now I think this is a board problem. What about switching port 1
from OTG to HOST only and avoiding kicking the timer in
dsps_musb_try_idle() in such a case? It seems we only need to do this
in OTG mode.

> Regards,
> -Bin.

Sebastian


\
 
 \ /
  Last update: 2013-07-29 20:01    [W:0.340 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site