linux-kernel - RE: [PATCH v4] Axi-usb: Add support for 64-bit addressing.

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Date:	Tue, 31 May 2016 05:15:10 +0000
From:	Nava kishore Manne <nava.manne@...inx.com>
To:	Shubhrajyoti Datta <shubhrajyoti.datta@...il.com>
CC:	Rob Herring <robh+dt@...nel.org>, Pawel Moll <pawel.moll@....com>,
	"Mark Rutland" <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	"Michal Simek" <michals@...inx.com>,
	Soren Brinkmann <sorenb@...inx.com>,
	"balbi@...com" <balbi@...com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	Hyun Kwon <hyunk@...inx.com>,
	"Radhey Shyam Pandey" <radheys@...inx.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v4] Axi-usb: Add support for 64-bit addressing.

Hi Shubhrajyoti,

	
	Thanks for the review...

> >  /**
> > + * xudc_write64 - write 64bit value to device registers
> > + * @ep: pointer to the usb device endpoint structure.
> > + * @offset: register offset
> > + * @val: data to be written
> > + **/
> > +static void xudc_write64(struct xusb_ep *ep, u32 offset, u64 val) {
> > +       struct xusb_udc *udc = ep->udc;
> > +
> > +       udc->write_fn(udc->addr, offset, lower_32_bits(val));
> > +       udc->write_fn(udc->addr, offset+0x04, upper_32_bits(val));
> 
> can we move this to a single 64 bit write?

Initially I sent the patches with writeq() ,lo_hi_writeq()  later we decided to replace with write_fun().
The reason for this is lo_hi_writeq() always assumes a little-endian register, so it's broken if anyone builds this device with big-endian registers.
So replaced the 64bit calls with write_fun() as suggested by Arnd Bergmann. Hope it clears your query.
Please refer to the below thread

	http://lkml.iu.edu/hypermail/linux/kernel/1604.2/02046.html 


Regards,
Navakishore.