linux-kernel - Re: [PATCH] usb: musb: dsps: implement vbus

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Message-ID: <56167D41.3010902@dev.rtsoft.ru>
Date:	Thu, 08 Oct 2015 17:27:13 +0300
From:	Roman Alyautdin <ralyautdin@....rtsoft.ru>
To:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
CC:	balbi@...com, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] usb: musb: dsps: implement vbus_status method

On 08/10/15 17:07, Sergei Shtylyov wrote:
> On 10/8/2015 4:50 PM, Sergei Shtylyov wrote:
>
>>> Implement vbus_status  method of musb_platform_ops that allows
>>> musb_core to properly represent the VBUS status of musb_dsps devices in
>>> corresponding sysfs entry
>>>
>>> Signed-off-by: Roman Alyautdin <ralyautdin@....rtsoft.ru>
>>> ---
>>>   drivers/usb/musb/musb_dsps.c |   13 +++++++++++++
>>>   1 file changed, 13 insertions(+)
>>>
>>> diff --git a/drivers/usb/musb/musb_dsps.c 
>>> b/drivers/usb/musb/musb_dsps.c
>>> index 84512d1..9c00edf 100644
>>> --- a/drivers/usb/musb/musb_dsps.c
>>> +++ b/drivers/usb/musb/musb_dsps.c
>>> @@ -632,6 +632,18 @@ static void dsps_read_fifo32(struct musb_hw_ep 
>>> *hw_ep,
>>> u16 len, u8 *dst)
>>>       }
>>>   }
>>>
>>> +static int dsps_musb_vbus_status(struct musb *musb)
>>> +{
>>> +    void __iomem *mregs = musb->mregs;
>>> +    u8 devctl;
>>> +
>>> +    devctl = dsps_readb(mregs, MUSB_DEVCTL);
>>> +    if ((devctl & MUSB_DEVCTL_VBUS) == (3 << MUSB_DEVCTL_VBUS_SHIFT))
>>
>>     I don't see why this has to be is implemented in the DSPS glue 
>> layer. The
>> DevCtl register is a standard MUSB one.
>
>    Looking at the musb_platform_get_vbus_status(), it's unclear why it 
> returns 0 if the vbus_status() method id undefined. I think we should 
> read the DevCtl registre here, removing the FIXME at the call site.

Maybe it is worth to return -EINVAL from musb_platform_get_vbus_status 
in case of method is undefined and keep current logic of interface 
implementation in platform-specific driver.

Hence print "Vbus unknown" in musb_vbus_show() in case of -EINVAL from 
musb_platform_get_vbus_status

Regards,
Roman


>
> MBR, Sergei
>

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