linux-kernel - Re: [PATCH] usb: ehci-msm: Don't ioremap configuration space exclusively

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Message-ID: <CAFp+6iHG92RdmAaNNMcJYgzi6kZP5sWirdx7GQoTU8eY1s7kVQ@mail.gmail.com>
Date:	Wed, 15 Apr 2015 21:28:04 +0530
From:	Vivek Gautam <gautamvivek1987@...il.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	"Ivan T. Ivanov" <ivan.ivanov@...aro.org>,
	Vivek Gautam <gautam.vivek@...sung.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	USB list <linux-usb@...r.kernel.org>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH] usb: ehci-msm: Don't ioremap configuration space exclusively

On Thu, Apr 9, 2015 at 8:19 PM, Alan Stern <stern@...land.harvard.edu> wrote:
> On Thu, 9 Apr 2015, Ivan T. Ivanov wrote:
>
>> This allow same IO space to be shared between HCD and Device
>> controller driver. Which can be loaded simultaneously and
>> started/stopped on demand by USB OTG PHY driver.

Are you sure ?
Will ehci controller registers overlap with the Device controller's register
region ?

>
> You really should CC the person who wrote the code you are changing.
> This is almost exactly the same as reverting commit 70843f623b58 (usb:
> host: ehci-msm: Use devm_ioremap_resource instead of devm_ioremap).
>
> Vivek, what do you think?

Yea, the idea was to prevent any unintentional overlapping of
ioremapped regions by two device drivers.

I still believe that the register region used by ehci-msm may
not be overlapping with the device-controller's register memory region.

>
> Alan Stern
>
>> Signed-off-by: Ivan T. Ivanov <ivan.ivanov@...aro.org>
>> ---
>>  drivers/usb/host/ehci-msm.c | 10 +++++++---
>>  1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/host/ehci-msm.c b/drivers/usb/host/ehci-msm.c
>> index 9db74ca..f059e15 100644
>> --- a/drivers/usb/host/ehci-msm.c
>> +++ b/drivers/usb/host/ehci-msm.c
>> @@ -88,13 +88,17 @@ static int ehci_msm_probe(struct platform_device *pdev)
>>       }
>>
>>       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> -     hcd->regs = devm_ioremap_resource(&pdev->dev, res);
>> +     if (!res)
>> +             return -ENODEV;
>> +
>> +     hcd->rsrc_start = res->start;
>> +     hcd->rsrc_len = resource_size(res);
>> +
>> +     hcd->regs = devm_ioremap(&pdev->dev, hcd->rsrc_start, hcd->rsrc_len);
>>       if (IS_ERR(hcd->regs)) {
>>               ret = PTR_ERR(hcd->regs);
>>               goto put_hcd;
>>       }
>> -     hcd->rsrc_start = res->start;
>> -     hcd->rsrc_len = resource_size(res);
>>
>>       /*
>>        * OTG driver takes care of PHY initialization, clock management,
>> --
>> 1.9.1
>>
>>
>>
>
> --
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-- 
Best Regards
Vivek Gautam
Samsung R&D Institute, Bangalore
India
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