Re: [PATCH v15 3/8] mtd: spi-nor: sfdp: Clarify that nor->read_{opcode, dummy} are uninitialized

[Michael Walle <michael@walle.cc>]

Am 2022-05-10 00:10, schrieb tkuw584924@gmail.com:
> From: Tudor Ambarus <tudor.ambarus@microchip.com>
> 
> nor->read_{opcode, dummy} are uninitialized (value zero) at SFDP 
> parsing
> time. Clarify that in the code.
> 
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> Tested-By: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
> ---
>  drivers/mtd/spi-nor/sfdp.c | 18 ++++++++----------
>  1 file changed, 8 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> index 61ae8c8c5237..058ce218d2af 100644
> --- a/drivers/mtd/spi-nor/sfdp.c
> +++ b/drivers/mtd/spi-nor/sfdp.c
> @@ -178,12 +178,10 @@ static int spi_nor_read_raw(struct spi_nor *nor,
> u32 addr, size_t len, u8 *buf)
>  static int spi_nor_read_sfdp(struct spi_nor *nor, u32 addr,
>  			     size_t len, void *buf)
>  {
> -	u8 addr_nbytes, read_opcode, read_dummy;
> +	u8 addr_nbytes;
>  	int ret;
> 
> -	read_opcode = nor->read_opcode;
>  	addr_nbytes = nor->addr_nbytes;
> -	read_dummy = nor->read_dummy;
> 
>  	nor->read_opcode = SPINOR_OP_RDSFDP;
>  	nor->addr_nbytes = 3;
> @@ -191,9 +189,10 @@ static int spi_nor_read_sfdp(struct spi_nor *nor, 
> u32 addr,
> 
>  	ret = spi_nor_read_raw(nor, addr, len, buf);
> 
> -	nor->read_opcode = read_opcode;
>  	nor->addr_nbytes = addr_nbytes;
> -	nor->read_dummy = read_dummy;
> +	/* Restore setup to its uninitialized state. */
> +	nor->read_opcode = 0;
> +	nor->read_dummy = 0;
> 
>  	return ret;
>  }
> @@ -690,7 +689,7 @@ static const u32 *spi_nor_get_map_in_use(struct
> spi_nor *nor, const u32 *smpt,
>  	u32 addr;
>  	int err;
>  	u8 i;
> -	u8 addr_nbytes, read_opcode, read_dummy;
> +	u8 addr_nbytes;
>  	u8 read_data_mask, map_id;
> 
>  	/* Use a kmalloc'ed bounce buffer to guarantee it is DMA-able. */
> @@ -699,8 +698,6 @@ static const u32 *spi_nor_get_map_in_use(struct
> spi_nor *nor, const u32 *smpt,
>  		return ERR_PTR(-ENOMEM);
> 
>  	addr_nbytes = nor->addr_nbytes;
> -	read_dummy = nor->read_dummy;
> -	read_opcode = nor->read_opcode;
> 
>  	map_id = 0;
>  	/* Determine if there are any optional Detection Command Descriptors 
> */
> @@ -757,8 +754,9 @@ static const u32 *spi_nor_get_map_in_use(struct
> spi_nor *nor, const u32 *smpt,
>  out:
>  	kfree(buf);
>  	nor->addr_nbytes = addr_nbytes;
> -	nor->read_dummy = read_dummy;
> -	nor->read_opcode = read_opcode;
> +	/* Restore setup to its uninitialized state. */

Who is modifying this? FWIW, I don't like this because it's now
different than all the other occurrences of this pattern.
Ultimately, I'd like to get rid of all these

saved_params = params;
params = new_params;
spi_nor_call()
params = saved_params;

And instead use something like

__spi_nor_call(non_default_params);

-michael

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