linux-kernel - Re: [PATCH 01/13] spi: spi-mem: Add DTR templates for cmd, address, dummy and data phase

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Date:   Mon, 23 Aug 2021 09:57:38 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Apurva Nandan <a-nandan@...com>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        Patrice Chotard <patrice.chotard@...s.st.com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <linux-spi@...r.kernel.org>, Pratyush Yadav <p.yadav@...com>
Subject: Re: [PATCH 01/13] spi: spi-mem: Add DTR templates for cmd, address,
 dummy and data phase

On Tue, 13 Jul 2021 13:05:26 +0000
Apurva Nandan <a-nandan@...com> wrote:

> Setting dtr field of spi_mem_op is useful when creating templates
> for DTR ops in spinand.h. Also, 2 bytes cmd phases are required when
> operating in Octal DTR SPI mode.
> 
> Create new templates for dtr mode cmd, address, dummy and data phase
> in spi_mem_op, which set the dtr field to 1 and also allow passing
> the nbytes for the cmd phase.
> 
> Signed-off-by: Apurva Nandan <a-nandan@...com>
> ---
>  include/linux/spi/spi-mem.h | 87 ++++++++++++++++++++++++++-----------
>  1 file changed, 61 insertions(+), 26 deletions(-)
> 
> diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h
> index 85e2ff7b840d..73e52a3ecf66 100644
> --- a/include/linux/spi/spi-mem.h
> +++ b/include/linux/spi/spi-mem.h
> @@ -13,46 +13,81 @@
>  
>  #include <linux/spi/spi.h>
>  
> -#define SPI_MEM_OP_CMD(__opcode, __buswidth)			\
> -	{							\
> -		.buswidth = __buswidth,				\
> -		.opcode = __opcode,				\
> -		.nbytes = 1,					\
> +#define SPI_MEM_OP_CMD_ALL_ARGS(__nbytes, __opcode, __buswidth, __dtr)	\
> +	{								\
> +		.buswidth = __buswidth,					\
> +		.opcode = __opcode,					\
> +		.nbytes = __nbytes,					\
> +		.dtr = __dtr,						\
>  	}
>  
> -#define SPI_MEM_OP_ADDR(__nbytes, __val, __buswidth)		\
> -	{							\
> -		.nbytes = __nbytes,				\
> -		.val = __val,					\
> -		.buswidth = __buswidth,				\
> +#define SPI_MEM_OP_CMD(__opcode, __buswidth)				\
> +	SPI_MEM_OP_CMD_ALL_ARGS(1, __opcode, __buswidth, 0)
> +
> +#define SPI_MEM_OP_CMD_DTR(__nbytes, __opcode, __buswidth)		\
> +	SPI_MEM_OP_CMD_ALL_ARGS(__nbytes, __opcode, __buswidth, 1)

I don't see the benefit of those ALL_ARGS() macros compared to the
definition of the _DTR() variants using raw struct initializers, but if
you think we will add more optional args and really care about saving a
few lines of code, maybe it'd be better to have something like:

#define SPI_MEM_OP_DTR .dtr = true
#define SPI_MEM_OP_CMD_BYTES(val) .nbytes = val

#define SPI_MEM_OP_EXT_CMD(__opcode, __buswidth, ...) \
	{ \
		.buswidth = __buswidth, \
		.opcode = __opcode, \
		__VA_ARGS__, \
	}

#define SPI_MEM_OP_CMD(__opcode, __buswidth) \
	SPI_MEM_OP_EXT_CMD(__opcode, __buswidth, \
			   SPI_MEM_OP_CMD_BYTES(1))

#define SPI_MEM_OP_CMD_DTR(__nbytes, __opcode, __buswidth) \
	SPI_MEM_OP_EXT_CMD(__opcode, __buswidth, \
			   SPI_MEM_OP_CMD_BYTES(__nbytes), \
			   SPI_MEM_OP_DTR)

so you don't have to patch all users every time you add an argument.