linux-kernel - Re: [PATCH v5 3/5] mtd: devices: m25p80: add support for mmap read request

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Date:	Thu, 11 Feb 2016 11:03:50 +0530
From:	Vignesh R <vigneshr@...com>
To:	Mark Brown <broonie@...nel.org>
CC:	Tony Lindgren <tony@...mide.com>,
	Brian Norris <computersforpeace@...il.com>,
	Rob Herring <robh+dt@...nel.org>,
	Russell King <linux@....linux.org.uk>, <hramrach@...il.com>,
	<devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>
Subject: Re: [PATCH v5 3/5] mtd: devices: m25p80: add support for mmap read
 request



On 02/10/2016 01:06 AM, Mark Brown wrote:
> On Fri, Dec 11, 2015 at 09:39:58AM +0530, Vignesh R wrote:
> 
>> +	if (spi_flash_read_supported(spi)) {
>> +		struct spi_flash_read_message msg;
>> +		int ret;
>> +
>> +		msg.buf = buf;
>> +		msg.from = from;
>> +		msg.len = len;
>> +		msg.read_opcode = nor->read_opcode;
>> +		msg.addr_width = nor->addr_width;
>> +		msg.dummy_bytes = dummy;
>> +		/* TODO: Support other combinations */
>> +		msg.opcode_nbits = SPI_NBITS_SINGLE;
>> +		msg.addr_nbits = SPI_NBITS_SINGLE;
>> +		msg.data_nbits = m25p80_rx_nbits(nor);
>> +
>> +		ret = spi_flash_read(spi, &msg);
>> +		*retlen = msg.retlen;
>> +		return ret;
> 
> Looking at this I can't help but think that spi_flash_read() ought to
> have the stub in rather than the caller.  But given that we're pretty
> much only ever expecting one user I'm not 100% sure it actually matters.

Well, my initial patch set passed long list of arguments to
spi_flash_read(), but Brian suggested to use struct[1] in order to avoid
unnecessary churn when things need changed in the API.


[1] https://lkml.org/lkml/2015/11/11/454

-- 
Regards
Vignesh