RE: [PATCH v3] Axi-usb: Add support for 64-bit addressing.

[Nava kishore Manne]

> -----Original Message-----
> From: Arnd Bergmann [mailto:arnd@xxxxxxxx]
> Sent: Tuesday, May 24, 2016 2:21 PM
> To: Nava kishore Manne <navam@xxxxxxxxxx>
> Cc: robh+dt@xxxxxxxxxx; pawel.moll@xxxxxxx; mark.rutland@xxxxxxx;
> ijc+devicetree@xxxxxxxxxxxxxx; galak@xxxxxxxxxxxxxx; Michal Simek
> <michals@xxxxxxxxxx>; Soren Brinkmann <sorenb@xxxxxxxxxx>;
> balbi@xxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; Hyun Kwon
> <hyunk@xxxxxxxxxx>; Nava kishore Manne <navam@xxxxxxxxxx>; Radhey
> Shyam Pandey <radheys@xxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx; linux-
> arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3] Axi-usb: Add support for 64-bit addressing.
> 
> On Tuesday, May 24, 2016 10:51:08 AM CEST Nava kishore Manne wrote:
> > diff --git a/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > b/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > index 47b4e39..09df757 100644
> > --- a/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > +++ b/Documentation/devicetree/bindings/usb/udc-xilinx.txt
> > @@ -1,18 +1,23 @@
> >  Xilinx USB2 device controller
> >
> >  Required properties:
> > -- compatible		: Should be "xlnx,usb2-device-4.00.a"
> > +- compatible		: Should be "xlnx,usb2-device-4.00.a" or
> > +			  "xlnx,usb2-device-5.00"
> >  - reg			: Physical base address and size of the USB2
> >  			  device registers map.
> >  - interrupts		: Should contain single irq line of USB2 device
> >  			  controller
> >  - xlnx,has-builtin-dma	: if DMA is included
> > +- dma-ranges		: Should be as the following
> > +			  <child-bus-address, parent-bus-address, length>
> 
> A USB host should not have any children that are DMA capable, I think, so
> this property doesn't make sense here. It should be part of the parent bus.
> 
Will send next version (v4) by removing this property from the DT.

> > +- xlnx,addrwidth	: Should be the dma addressing size in bits(ex: 64
> bits)
> 
> I'm still unconvinced about the property definition here. What are the
> possible options for the IP block? I don't think I ever saw a reply from you to
> my earlier questions.
> 

Sorry Let me clearly explain

>From the IP version 5.0 onwards The IP support both 32-bit and 64-bit addressing.
But the older version of the IP's supports only 32-bit addressing.

This addrwidth property differentiates the address width for the new IP (I mean 5.0 version on wards)
For older IP it will be always 32-bit.

Please let me know if you are still not clear.

Regards,
Navakishore.


> > @@ -214,6 +223,20 @@ static const struct usb_endpoint_descriptor
> config_bulk_out_desc = {
> >  	.wMaxPacketSize		= cpu_to_le16(EP0_MAX_PACKET),
> >  };
> >
> > +/**
> > + * xudc_write64 - write 64bit value to device registers
> > + * @addr: base addr of device registers
> > + * @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)); }
> > +
> >  /**
> >   * xudc_write32 - little endian write to device registers
> >   * @addr: base addr of device registers @@ -330,8 +353,13 @@ static
> > int xudc_start_dma(struct xusb_ep *ep, dma_addr_t src,
> >  	 * destination registers and then set the length
> >  	 * into the DMA length register.
> >  	 */
> > -	udc->write_fn(udc->addr, XUSB_DMA_DSAR_ADDR_OFFSET, src);
> > -	udc->write_fn(udc->addr, XUSB_DMA_DDAR_ADDR_OFFSET, dst);
> > +	if (udc->dma_addrwidth > 32) {
> > +		xudc_write64(ep, XUSB_DMA_DSAR_ADDR_OFFSET_LSB,
> src);
> > +		xudc_write64(ep, XUSB_DMA_DDAR_ADDR_OFFSET_LSB,
> dst);
> > +	} else {
> > +		udc->write_fn(udc->addr,
> XUSB_DMA_DSAR_ADDR_OFFSET, src);
> > +		udc->write_fn(udc->addr,
> XUSB_DMA_DDAR_ADDR_OFFSET, dst);
> > +	}
> >  	udc->write_fn(udc->addr, XUSB_DMA_LENGTH_OFFSET, length);
> >
> 
> This looks good.
> 
> 	Arnd