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

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Date:   Tue, 18 Sep 2018 10:22:11 +0200
From:   Frieder Schrempf <frieder.schrempf@...eet.de>
To:     Boris Brezillon <boris.brezillon@...tlin.com>,
        Yogesh Gaur <yogeshnarayan.gaur@....com>
Cc:     linux-mtd@...ts.infradead.org, marek.vasut@...il.com,
        linux-spi@...r.kernel.org, devicetree@...r.kernel.org,
        robh@...nel.org, mark.rutland@....com, shawnguo@...nel.org,
        linux-arm-kernel@...ts.infradead.org, computersforpeace@...il.com,
        linux-kernel@...r.kernel.org
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@....com> 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.

Regards,
Frieder

> 
> Regards,
> 
> Boris
>