RE: [PATCH v2 1/5] spi: spi-mem: Add driver for NXP FlexSPI controller

[Yogesh Narayan Gaur]

Hi Frieder,

> -----Original Message-----
> From: Frieder Schrempf [mailto:frieder.schrempf@xxxxxxxxx]
> Sent: Tuesday, September 18, 2018 1:52 PM
> To: Boris Brezillon <boris.brezillon@xxxxxxxxxxx>; Yogesh Narayan Gaur
> <yogeshnarayan.gaur@xxxxxxx>
> Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx; marek.vasut@xxxxxxxxx; linux-
> spi@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; robh@xxxxxxxxxx;
> mark.rutland@xxxxxxx; shawnguo@xxxxxxxxxx; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; computersforpeace@xxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 1/5] spi: spi-mem: Add driver for NXP FlexSPI controller
> 
> Hi Boris, Yogesh,
> 
> On 17.09.2018 13:37, Boris Brezillon wrote:
> > Hi Yogesh,
> >
> > On Mon, 17 Sep 2018 15:18:26 +0530
> > Yogesh Gaur <yogeshnarayan.gaur@xxxxxxx> wrote:
> >
> >> +
> >> +	/*
> >> +	 * R/W functions for big- or little-endian registers:
> >> +	 * The FSPI controller's endianness is independent of
> >> +	 * the CPU core's endianness. So far, although the CPU
> >> +	 * core is little-endian the FSPI controller can use
> >> +	 * big-endian or little-endian.
> >> +	 */
> >> +	if (of_property_read_bool(np, "big-endian")) {
> >> +		f->write = fspi_writel_be;
> >> +		f->read = fspi_readl_be;
> >> +	} else {
> >> +		f->write = fspi_writel;
> >> +		f->read = fspi_readl;
> >> +	}
> >
> > Hm, isn't it something you can extract from the compatible string? I'd
> > rather not allow users to set that in their DT if it's not something
> > you can change.
> 
> This was copied from the QSPI driver, but I think Boris is right. This seems to be a
> fixed SOC-specific setting and we shouldn't set it in the DT. This applies to QSPI
> and FSPI alike.
> 

Yes, it can be modified. Instead of reading endianness property from device tree can be moved to the platform structure nxp_fspi_devtype_data which is linked with the compatible string
{ .compatible = "nxp,lx2160a-fspi", .data = (void *)&lx2160a_data, }

Thanks.

Would send the changes in next version.

--
Regards,
Yogesh Gaur.

> Regards,
> Frieder
> 
> >
> > Regards,
> >
> > Boris
> >