linux-kernel - Re: [PATCH v1 1/2] usb:dwc3: Enable support for 64-bit system

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Date:	Sat, 16 Jan 2016 11:00:31 +0700
From:	"Thang Q. Nguyen" <tqnguyen@....com>
To:	Felipe Balbi <balbi@...nel.org>
Cc:	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-usb@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm@...ts.infradead.org,
	Phong Vo <pvo@....com>, Loc Ho <lho@....com>, patches@....com
Subject: Re: [PATCH v1 1/2] usb:dwc3: Enable support for 64-bit system

Hi Balbi,
Thanks for your review and feedback.
I will remove WARN_ON() as in your feedback. I will wait some days to
see if any more comments before sending out an updated patch.

Thanks,
Thang Q. Nguyen
On Sat, Jan 16, 2016 at 10:28 AM, Felipe Balbi <balbi@...nel.org> wrote:
>
> Hi,
>
> "Thang Q. Nguyen" <tqnguyen@....com> writes:
>> Hi Balbi,
>>
>> On Thu, Jan 14, 2016 at 10:47 PM, Felipe Balbi <balbi@...nel.org> wrote:
>>>
>>>
>>> Hi,
>>>
>>> "Thang Q. Nguyen" <tqnguyen@....com> writes:
>>> > Add 64-bit DMA operation support to the USB DWC3 driver.
>>> > First attempt to set the coherent DMA mask for 64-bit DMA.
>>> > If that failed, attempt again with 32-bit DMA.
>>> >
>>> > Signed-off-by: Thang Q. Nguyen <tqnguyen@....com>
>>> > ---
>>> >  drivers/usb/dwc3/core.c | 15 +++++++++++++++
>>> >  1 file changed, 15 insertions(+)
>>> >
>>> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>>> > index 22b47973..9818d6b 100644
>>> > --- a/drivers/usb/dwc3/core.c
>>> > +++ b/drivers/usb/dwc3/core.c
>>> > @@ -829,6 +829,21 @@ static int dwc3_probe(struct platform_device *pdev)
>>> >       dwc->mem = mem;
>>> >       dwc->dev = dev;
>>> >
>>> > +     /* Try to set 64-bit DMA first */
>>> > +     if (WARN_ON(!pdev->dev.dma_mask))
>>>
>>> why the WARN_ON() ?
>>
>> In my opinion, pdev->dev.dma_mask is expected to be set correctly. And
>
> sure is, but a WARN_ON() will print out a stack dump, which looks
> scary. Besides, if it's not set you're already fixing the problem.
>
>> the issue happen just in case of DT boot and CONFIG_DMA_CMA=n, the
>> pdev->dev.dma_mask value is not set. So, I set WARN_ON there to notify
>
> why isn't it set ?
>
>> that we expect pdev->dev.dma_mask set but not.
>
> why don't you fix that case, instead ?
>
> --
> balbi



-- 

Thang Q. Nguyen    | Staff SW Eng.

C: +849.7684.7606 | O: +848.3770.0640

F: +848.3770.0641  | tqnguyen@....com