On Tuesday, August 18, 2015 at 10:18:33 PM, vikas wrote: > Hi, > > On 08/18/2015 12:03 PM, Graham Moore wrote: > > Hi all, > > > > On 08/18/2015 12:48 AM, Vikas MANOCHA wrote: > > > > [...] > > > >>>>> +Required properties: > >>>>> +- compatible : Should be "cdns,qspi-nor". > >>>>> +- reg : Contains two entries, each of which is a tuple consisting of > >>>>> a + physical address and length. The first entry is the address > >>>>> and + length of the controller register set. The second entry is > >>>>> the + address and length of the QSPI Controller data area. > >>>> > >>>> "Controller data area", i think it means mapped NOR Flash address ? > >>> > >>> Probably ; Graham ? > >>> > >>>> If yes, it would be more clear with "Physical base address & size of > >>>> NOR Flash". > >>> > >>> This is the Direct mode thing, correct ? We don't support this, so I > >>> think we should drop this bit altogether and keep only one single > >>> address in this field. > >> > >> No it's not. > > > > It's the location of the SRAM fifo. Also direct mode location I think, > > if that were ever used. > > Hmm...It is the base address of NOR flash. SRAM is not memory mapped. Huh ? I am inclined to trust Graham more -- I have seen memory mapped SRAM, but I have yet to see memory mapped SPI NOR. Also, the driver code clearly uses that area in a way one would use a memory mapped SRAM with FIFO on the other side. I think the above description is pretty much OK. > > The size is determined by a configuration parameter during system > > design. On Altera Cyclone5 the size is really big compared to SRAM > > fifo. I don't know why, maybe some hw engineer thought it would be > > better to have a large size in case direct mode was used. > > my comment is about second parameter of property "reg" which is NOR flash > address, so above explanation does not make sense for it. > Also in direct mode, sram does not come into play. This is absolutelly not a SPI NOR address. Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
