linux-kernel - Re: [PATCH 1/5] mtd: ofpart: grab device tree node directly from master device node

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Message-ID: <20151027084200.2434180f@bbrezillon>
Date:	Tue, 27 Oct 2015 08:42:00 +0100
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Brian Norris <computersforpeace@...il.com>
Cc:	<linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>,
	Marek Vasut <marex@...x.de>,
	Scott Wood <scottwood@...escale.com>,
	Josh Wu <josh.wu@...el.com>,
	Robert Jarzmik <robert.jarzmik@...e.fr>,
	Kyungmin Park <kyungmin.park@...sung.com>,
	Han Xu <han.xu@...escale.com>,
	Huang Shijie <shijie.huang@....com>
Subject: Re: [PATCH 1/5] mtd: ofpart: grab device tree node directly from
 master device node

Hi Brian,

On Mon, 26 Oct 2015 19:31:06 -0700
Brian Norris <computersforpeace@...il.com> wrote:

> It seems more logical to use a device node directly associated with the
> MTD master device (i.e., mtd->dev.of_node field) rather than requiring
> auxiliary partition parser information to be passed in by the driver in
> a separate struct.
> 
> This patch supports the mtd->dev.of_node field, deprecates the parser
> data 'of_node' field, and begins using the new convention for nand_base.
> Other NAND driver conversions may now follow.
> 
> Additional side benefit to assigning mtd->dev.of_node rather than using
> parser data: the driver core will automatically create a device -> node
> symlink for us.

I like the idea, but how about pushing the solution even further and
killing the ->flash_node field which AFAICT is rendered useless by
your patch?

Best Regards,

Boris

> 
> Signed-off-by: Brian Norris <computersforpeace@...il.com>
> ---
>  drivers/mtd/nand/nand_base.c   |  3 +++
>  drivers/mtd/ofpart.c           | 18 ++++++++++--------
>  drivers/mtd/spi-nor/spi-nor.c  |  1 +
>  include/linux/mtd/partitions.h |  4 +++-
>  4 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index cc74142938b0..d2e7fee2ac37 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -3990,6 +3990,9 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips,
>  	int ret;
>  
>  	if (chip->flash_node) {
> +		/* MTD can automatically handle DT partitions, etc. */
> +		mtd->dev.of_node = chip->flash_node;
> +
>  		ret = nand_dt_init(mtd, chip, chip->flash_node);
>  		if (ret)
>  			return ret;
> diff --git a/drivers/mtd/ofpart.c b/drivers/mtd/ofpart.c
> index aa26c32e1bc2..a5dfd73cfc7d 100644
> --- a/drivers/mtd/ofpart.c
> +++ b/drivers/mtd/ofpart.c
> @@ -35,10 +35,11 @@ static int parse_ofpart_partitions(struct mtd_info *master,
>  	int nr_parts, i;
>  
>  
> -	if (!data)
> -		return 0;
> -
> -	node = data->of_node;
> +	/*
> +	 * of_node can be provided through auxiliary parser data or (preferred)
> +	 * by assigning the master device
> +	 */
> +	node = data && data->of_node ? data->of_node : master->dev.of_node;
>  	if (!node)
>  		return 0;
>  
> @@ -120,10 +121,11 @@ static int parse_ofoldpart_partitions(struct mtd_info *master,
>  	} *part;
>  	const char *names;
>  
> -	if (!data)
> -		return 0;
> -
> -	dp = data->of_node;
> +	/*
> +	 * of_node can be provided through auxiliary parser data or (preferred)
> +	 * by assigning the master device
> +	 */
> +	dp = data && data->of_node ? data->of_node : master->dev.of_node;
>  	if (!dp)
>  		return 0;
>  
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index 49883905a434..8f9080c6db63 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -1258,6 +1258,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
>  		mtd->flags |= MTD_NO_ERASE;
>  
>  	mtd->dev.parent = dev;
> +	mtd->dev.of_node = np;
>  	nor->page_size = info->page_size;
>  	mtd->writebufsize = nor->page_size;
>  
> diff --git a/include/linux/mtd/partitions.h b/include/linux/mtd/partitions.h
> index 6a35e6de5da1..e742f34b67eb 100644
> --- a/include/linux/mtd/partitions.h
> +++ b/include/linux/mtd/partitions.h
> @@ -56,7 +56,9 @@ struct device_node;
>  /**
>   * struct mtd_part_parser_data - used to pass data to MTD partition parsers.
>   * @origin: for RedBoot, start address of MTD device
> - * @of_node: for OF parsers, device node containing partitioning information
> + * @of_node: for OF parsers, device node containing partitioning information.
> + *           This field is deprecated, as the device node should simply be
> + *           assigned to the master struct device.
>   */
>  struct mtd_part_parser_data {
>  	unsigned long origin;



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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