linux-kernel - Re: [PATCH v3 09/32] mtd: spi-nor: Pointer parameter for FSR in spi_nor_read

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Date:   Thu, 31 Oct 2019 11:53:52 +0100
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     <Tudor.Ambarus@...rochip.com>
Cc:     <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 09/32] mtd: spi-nor: Pointer parameter for FSR in
 spi_nor_read_fsr()

On Tue, 29 Oct 2019 11:17:02 +0000
<Tudor.Ambarus@...rochip.com> wrote:

> From: Tudor Ambarus <tudor.ambarus@...rochip.com>
> 
> Let the callers pass the pointer to the DMA-able buffer where
> the value of the Flag Status Register will be written. This way we
> avoid the casts between int and u8, which can be confusing.
> 
> Caller stops compare the return value of spi_nor_read_fsr() with negative,
> spi_nor_read_fsr() returns 0 on success and -errno otherwise.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@...rochip.com>
> ---
>  drivers/mtd/spi-nor/spi-nor.c | 38 ++++++++++++++++++++------------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> index dc44d1206f77..0d38aede4de7 100644
> --- a/drivers/mtd/spi-nor/spi-nor.c
> +++ b/drivers/mtd/spi-nor/spi-nor.c
> @@ -456,12 +456,15 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
>  	return ret;
>  }
>  
> -/*
> - * Read the flag status register, returning its value in the location
> - * Return the status register value.
> - * Returns negative if error occurred.
> +/**
> + * spi_nor_read_fsr() - Read the Flag Status Register.
> + * @nor:	pointer to 'struct spi_nor'
> + * @fsr:	pointer to a DMA-able buffer where the value of the
> + *              Flag Status Register will be written.
> + *
> + * Return: 0 on success, -errno otherwise.
>   */
> -static int spi_nor_read_fsr(struct spi_nor *nor)
> +static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr)
>  {
>  	int ret;
>  
> @@ -470,20 +473,18 @@ static int spi_nor_read_fsr(struct spi_nor *nor)
>  			SPI_MEM_OP(SPI_MEM_OP_CMD(SPINOR_OP_RDFSR, 1),
>  				   SPI_MEM_OP_NO_ADDR,
>  				   SPI_MEM_OP_NO_DUMMY,
> -				   SPI_MEM_OP_DATA_IN(1, nor->bouncebuf, 1));
> +				   SPI_MEM_OP_DATA_IN(1, fsr, 1));
>  
>  		ret = spi_mem_exec_op(nor->spimem, &op);
>  	} else {
>  		ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDFSR,
> -						    nor->bouncebuf, 1);
> +						    fsr, 1);
>  	}
>  
> -	if (ret) {
> +	if (ret)
>  		dev_err(nor->dev, "error %d reading FSR\n", ret);
> -		return ret;
> -	}
>  
> -	return nor->bouncebuf[0];
> +	return ret;
>  }
>  
>  /*
> @@ -705,17 +706,18 @@ static int spi_nor_clear_fsr(struct spi_nor *nor)
>  
>  static int spi_nor_fsr_ready(struct spi_nor *nor)
>  {
> -	int fsr = spi_nor_read_fsr(nor);
> -	if (fsr < 0)
> -		return fsr;
> +	int ret = spi_nor_read_fsr(nor, &nor->bouncebuf[0]);

Didn't comment on the previous patch, but why not simply pass
nor->bouncebuf here?

Anyway, that's just a detail.

Reviewed-by: Boris Brezillon <boris.brezillon@...labora.com>

> +
> +	if (ret)
> +		return ret;
>  
> -	if (fsr & (FSR_E_ERR | FSR_P_ERR)) {
> -		if (fsr & FSR_E_ERR)
> +	if (nor->bouncebuf[0] & (FSR_E_ERR | FSR_P_ERR)) {
> +		if (nor->bouncebuf[0] & FSR_E_ERR)
>  			dev_err(nor->dev, "Erase operation failed.\n");
>  		else
>  			dev_err(nor->dev, "Program operation failed.\n");
>  
> -		if (fsr & FSR_PT_ERR)
> +		if (nor->bouncebuf[0] & FSR_PT_ERR)
>  			dev_err(nor->dev,
>  			"Attempted to modify a protected sector.\n");
>  
> @@ -723,7 +725,7 @@ static int spi_nor_fsr_ready(struct spi_nor *nor)
>  		return -EIO;
>  	}
>  
> -	return fsr & FSR_READY;
> +	return nor->bouncebuf[0] & FSR_READY;
>  }
>  
>  static int spi_nor_ready(struct spi_nor *nor)