Re: [PATCH v2] mtd: spi-nor: handle unsupported FSR opcodes properly

[Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>]

On Thu, Jun 16, 2022 at 05:14:45AM -0700, Oleksandr Ocheretnyi wrote:
> Originally commit 094d3b9 ("mtd: spi-nor: Add USE_FSR flag for n25q*
> entries") and following one 8f93826 ("mtd: spi-nor: micron-st: convert
> USE_FSR to a manufacturer flag") enabled SPINOR_OP_RDFSR opcode handling
> ability, however some controller drivers still cannot handle it properly
> in the micron_st_nor_ready() call what breaks some mtd callbacks with
> next error logs:
> 
> mtdblock: erase of region [address1, size1] on "BIOS" failed
> mtdblock: erase of region [address2, size2] on "BIOS" failed
> 
> The Intel SPI controller does not support low level operations, like
> reading the flag status register (FSR). It only exposes a set of high
> level operations for software to use. For this reason check the return
> value of micron_st_nor_read_fsr() and if the operation was not
> supported, use the status register value only. This allows the chip to
> work even when attached to Intel SPI controller (there are such systems
> out there).
> 
> Signed-off-by: Oleksandr Ocheretnyi <oocheret@xxxxxxxxx>
> Link: https://lore.kernel.org/lkml/YmZUCIE%2FND82BlNh@lahna/
> ---
>  PATCH v2 updates PATCH v1 taking into account changes from
>  https://lore.kernel.org/linux-mtd/20220506105158.43613-1-mika.westerberg@xxxxxxxxxxxxxxx
>  to check -EOPNOTSUPP value from micron_st_nor_read_fsr() as well.
> 
>  drivers/mtd/spi-nor/micron-st.c | 12 ++++++++++--
>  drivers/spi/spi-intel.c         |  3 ++-
>  2 files changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/micron-st.c b/drivers/mtd/spi-nor/micron-st.c
> index a96f74e0f568..fd52e8feea44 100644
> --- a/drivers/mtd/spi-nor/micron-st.c
> +++ b/drivers/mtd/spi-nor/micron-st.c
> @@ -399,8 +399,16 @@ static int micron_st_nor_ready(struct spi_nor *nor)
>  		return sr_ready;
>  
>  	ret = micron_st_nor_read_fsr(nor, nor->bouncebuf);
> -	if (ret)
> -		return ret;
> +	if (ret < 0) {
> +		/*
> +		 * Some controllers, such as Intel SPI, do not support low
> +		 * level operations such as reading the flag status
> +		 * register. They only expose small amount of high level
> +		 * operations to the software. If this is the case we use
> +		 * only the status register value.
> +		 */
> +		return (ret == -ENOTSUPP || ret == -EOPNOTSUPP) ? sr_ready : ret;

The -EOPNOTSUPP here is not needed as you change the Intel SPI driver in
the below.

> +	}
>  
>  	if (nor->bouncebuf[0] & (FSR_E_ERR | FSR_P_ERR)) {
>  		if (nor->bouncebuf[0] & FSR_E_ERR)
> diff --git a/drivers/spi/spi-intel.c b/drivers/spi/spi-intel.c
> index 50f42983b950..f0313a718d1b 100644
> --- a/drivers/spi/spi-intel.c
> +++ b/drivers/spi/spi-intel.c
> @@ -352,7 +352,8 @@ static int intel_spi_hw_cycle(struct intel_spi *ispi, u8 opcode, size_t len)
>  		val |= HSFSTS_CTL_FCYCLE_RDSR;
>  		break;
>  	default:
> -		return -EINVAL;
> +		dev_dbg(ispi->dev, "%#x not supported\n", opcode);
> +		return -ENOTSUPP;
>  	}
>  
>  	if (len > INTEL_SPI_FIFO_SZ)
> -- 
> 2.27.0