Re: [PATCH V3 4/5] dwc3: host: Enable USB3 LPM capability

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On Wed, May 14, 2014 at 10:45:55PM +0800, Felipe Balbi wrote:
> On Wed, May 14, 2014 at 12:13:08PM +0530, Pratyush Anand wrote:
> > Hi Paul/Felip,
> > 
> > On Wed, May 07, 2014 at 11:15:33AM +0530, Pratyush Anand wrote:
> > > Hi Paul,
> > > 
> > > On Tue, May 06, 2014 at 11:54:19AM +0800, Pratyush ANAND wrote:
> > > > All dwc3 based xhci host controller supports USB3.0 LPM functionality.
> > > > Therefore enable it in platform data for all dwc3 based xhci device.
> > > > 
> > > > Signed-off-by: Pratyush Anand <pratyush.anand@xxxxxx>
> > > > ---
> > > >  drivers/usb/dwc3/host.c | 12 ++++++++++++
> > > >  1 file changed, 12 insertions(+)
> > > > 
> > > > diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
> > > > index 32db328..1fda6e8 100644
> > > > --- a/drivers/usb/dwc3/host.c
> > > > +++ b/drivers/usb/dwc3/host.c
> > > > @@ -16,12 +16,14 @@
> > > >   */
> > > >  
> > > >  #include <linux/platform_device.h>
> > > > +#include <linux/usb/xhci_pdriver.h>
> > > >  
> > > >  #include "core.h"
> > > >  
> > > >  int dwc3_host_init(struct dwc3 *dwc)
> > > >  {
> > > >  	struct platform_device	*xhci;
> > > > +	struct usb_xhci_pdata	pdata;
> > > >  	int			ret;
> > > >  
> > > >  	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
> > > > @@ -46,6 +48,16 @@ int dwc3_host_init(struct dwc3 *dwc)
> > > >  		goto err1;
> > > >  	}
> > > >  
> > > > +	memset(&pdata, 0, sizeof(pdata));
> > > > +
> > > > +	pdata.usb3_lpm_capable = 1;
> > > 
> > > Even though all dwc3 platform is usb3 lpm capable, I would like to
> > > make it optional, as I see some performance impact when capability is
> > > enabled vs not enabled.
> > > 
> > > When enabled:
> > > ./testusb -a -t 2 -c 1000000 -s 1024
> > > takes 198 sec to execute
> > > vs when not enabled , it takes 169 sec to execute.
> > > 
> > > And this impact is with a gadget with maxburst and mult as 0.
> > > Performance will be impacted more with higher maxburst and mult.
> > > 
> > > So making it optional would be a better choice. What do you say.
> > 
> > Do you think that it would be wiser to add an optional flag in
> > usb3-lpm-enable in dwc3 dt? If yes, I will send a quick next revision,
> > else I think patches can be applied.
> 
> in that case, let's wrap with a Kconfig boolean symbol. It's not worth
> to add DT for this, it's either enabled for all instances, or for none.
> 

OK.

Regards
Pratyush

> cheers
> 
> -- 
> balbi


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