Re: [PATCH 1/2] usb: dwc2: Option to disable dma descriptor mode

[Dinh Nguyen <dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org>]

On Tue, 2014-05-06 at 19:39 +0400, Sergei Shtylyov wrote:
> Hello.
> 
> On 05/06/2014 02:23 AM, dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org wrote:
> 
> > From: Dinh Nguyen <dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org>
> 
> > Even though the IP supports Descriptor DMA mode, it does not support SPLIT
> > transactions in this mode. Since the driver can get the Descriptor DMA mode
> > support from hardware, the driver in its currently form cannot fully support
> > LS/FS devices connected to a HS Hub when Descriptor DMA mode is enabled in the
> > driver. Thus, we give the option to disable Descriptor DMA from device tree.
> 
> > Signed-off-by: Dinh Nguyen <dinguyen-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org>
> > ---
> >   drivers/usb/dwc2/platform.c |    3 +++
> >   1 file changed, 3 insertions(+)
> 
> > diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> > index eaba547..cb2133c 100644
> > --- a/drivers/usb/dwc2/platform.c
> > +++ b/drivers/usb/dwc2/platform.c
> > @@ -123,6 +123,7 @@ static int dwc2_driver_probe(struct platform_device *dev)
> >   	struct resource *res;
> >   	int retval;
> >   	int irq;
> > +	u32 prop;
> >
> >   	if (usb_disabled())
> >   		return -ENODEV;
> > @@ -135,6 +136,8 @@ static int dwc2_driver_probe(struct platform_device *dev)
> >   		dwc2_set_all_params(&defparams, -1);
> >   		params = &defparams;
> >   	}
> > +	if (!of_property_read_u32(dev->dev.of_node, "dma-desc-enable", &prop))
> > +		defparams.dma_desc_enable = prop;
> 
>     You don't really need a helper local variable here, the variable receiving 
> the property value won't be changed if there was an error retrieving it.
> 

Ah yes, you're right. Thanks for the review.

Dinh
> WBR, Sergei
> 


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