linux-kernel - Re: [PATCH] usb: musb: dsps: handle the otg_state_a_wait_vrise

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Message-ID: <5666E9BE.5070907@ti.com>
Date:	Tue, 8 Dec 2015 08:31:26 -0600
From:	Bin Liu <b-liu@...com>
To:	Felipe Balbi <balbi@...com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <stable@...r.kernel.org>
Subject: Re: [PATCH] usb: musb: dsps: handle the
 otg_state_a_wait_vrise_timeout case

Felipe,

On 12/08/2015 08:20 AM, Felipe Balbi wrote:
>
> Hi,
>
> Gregory CLEMENT <gregory.clement@...e-electrons.com> writes:
>>>>> if it is the case then it didn't fix the issue I had.
>>>>>
>>>>> I activated the following debug line:
>>>>>
>>>>> [musb_hdrc]musb_interrupt =_ "** IRQ %s usb%04x tx%04x rx%04x\012"
>>>>> [musb_dsps]dsps_interrupt =p "usbintr (%x) epintr(%x)\012"
>>>>>
>>>>> But I didn't get any interrupt while disconnecting the cable without any
>>>>> device connected on it (whereas I got an interrupt when I connected it).
>>>>>
>>>>> Note that I applied this patch instead of the "usb: musb: dsps: handle
>>>>> the otg_state_a_wait_vrise_timeout case", is what you had in mind ?
>>>
>>> yeah, that's what I had in mind. But your patch seems wrong :-)
>>>
>>> I tried writing a more correct version here and found 2 issues:
>>>
>>> a) bit 3 doesn't do anything :-p I cannot read IRQs from mentor's
>>> registers
>>>
>>> b) when setting RESET_ISOLATION bit, reads of CTRL register hang. Note
>>> that according to TRM, RESET_ISOLATION _must_ be set prior to a soft
>>> reset and cleared afterwards. But right after setting RESET_ISOLATION,
>>> if I try a read of CTRL, it'll hang forever.
>>
>> The datasheet seems not very coherent about it,
>>
>> on one side we have:
>> "This bit should be set high prior to setting bit 0 and cleared after bit 0
>> is cleared."
>>
>> and on the other side:
>> "Both the soft_reset and soft_reset_isolation bits should be asserted
>> simultaneously."
>>
>> The hang you saw could be explained by the following:
>> "Setting only the soft_reset_isolation bit will cause all USB0 output
>> signals to go to a known constant value via multiplexers.
>> This will
>> prevent future access to USB0."  page 2567
>
> good catch. Setting them together makes the hang go away.
>
> I still have the other problem, which is legacy IRQ reporting mode not
> really working.
>

I never tried to change the IRQ mapping. The 8 MUSB interrupt will be 
the same no matter where they are reported from. What do you expect when 
switch to the MUSB IRQ reporting mode?

Regards,
-Bin.

-- 
Regards,
-Bin.
--
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