linux-kernel - Re: [PATCH v5 6/6] usb: musb: dsps: Enable sw babble control for newer silicon

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Date:	Thu, 22 May 2014 18:22:52 +0530
From:	George Cherian <george.cherian@...com>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
	<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>
CC:	<gregkh@...uxfoundation.org>, <balbi@...com>, <zonque@...il.com>,
	<b-liu@...com>
Subject: Re: [PATCH v5 6/6] usb: musb: dsps: Enable sw babble control for
 newer silicon

On 5/22/2014 5:28 PM, Sergei Shtylyov wrote:
> Hello.
>
> On 22-05-2014 10:29, George Cherian wrote:
>
>> Find whether we are running on newer silicon. The babble control
>> register reads 0x4 by default in newer silicon as opposed to 0
>> in old versions of AM335x. Based on this enable the sw babble
>> control logic.
>
>> Signed-off-by: George Cherian <george.cherian@...com>
>> ---
>>   drivers/usb/musb/musb_dsps.c | 38 
>> ++++++++++++++++++++++++++++++++------
>>   1 file changed, 32 insertions(+), 6 deletions(-)
>
>> diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
>> index 868caf8..2ced061 100644
>> --- a/drivers/usb/musb/musb_dsps.c
>> +++ b/drivers/usb/musb/musb_dsps.c
> [...]
>> @@ -469,6 +470,19 @@ static int dsps_musb_init(struct musb *musb)
>>       val &= ~(1 << wrp->otg_disable);
>>       dsps_writel(musb->ctrl_base, wrp->phy_utmi, val);
>>
>> +    /*
>> +     *  Check whether the dsps version has babble control enabled.
>
>    One space too many before this sentence.
>
>> +     * In latest silicon revision the babble control logic is enabled.
>> +     * If MUSB_BABBLE_CTL returns 0x4 then we have the babble control
>> +     * logic enabled.
>> +     */
>> +    val = dsps_readb(musb->mregs, MUSB_BABBLE_CTL);
>> +    if (val == MUSB_BABBLE_RCV_DISABLE) {
>> +        glue->sw_babble_enabled = true;
>> +        val |= MUSB_BABBLE_SW_SESSION_CTRL;
>> +        dsps_writeb(musb->mregs, MUSB_BABBLE_CTL, val);
>> +    }
>> +
>
>    Hm, from the register offset that you declared in the previous 
> patch, I got an impression that this is a new standard MUSB register? 
Its very AM335x MUSB specific register, not a standard one.
Unfortunately the designers put it as part of MUSB core regs.
> Shouldn't this check be done in the generic MUSB code then?
>
> WBR, Sergei
>


-- 
-George

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