linux-kernel - Re: [PATCH v10 12/17] mtd: spi-nor: sfdp: detect Soft Reset sequence support from BFPT

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Message-ID: <5f9a93d0-833c-8976-c6d3-2043e65b1b66@microchip.com>
Date:   Wed, 8 Jul 2020 16:08:21 +0000
From:   <Tudor.Ambarus@...rochip.com>
To:     <p.yadav@...com>, <miquel.raynal@...tlin.com>, <richard@....at>,
        <vigneshr@...com>, <broonie@...nel.org>,
        <Nicolas.Ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <Ludovic.Desroches@...rochip.com>, <matthias.bgg@...il.com>,
        <michal.simek@...inx.com>, <linux-mtd@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>
CC:     <nsekhar@...com>, <boris.brezillon@...labora.com>
Subject: Re: [PATCH v10 12/17] mtd: spi-nor: sfdp: detect Soft Reset sequence
 support from BFPT

On 6/23/20 9:30 PM, Pratyush Yadav wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> A Soft Reset sequence will return the flash to Power-on-Reset (POR)
> state. It consists of two commands: Soft Reset Enable and Soft Reset.
> Find out if the sequence is supported from BFPT DWORD 16.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> ---
>  drivers/mtd/spi-nor/core.h | 1 +
>  drivers/mtd/spi-nor/sfdp.c | 4 ++++
>  drivers/mtd/spi-nor/sfdp.h | 2 ++
>  3 files changed, 7 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 6338d32a0d77..79ce952c0539 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -26,6 +26,7 @@ enum spi_nor_option_flags {
>         SNOR_F_HAS_SR_TB_BIT6   = BIT(11),
>         SNOR_F_HAS_4BIT_BP      = BIT(12),
>         SNOR_F_HAS_SR_BP3_BIT6  = BIT(13),
> +       SNOR_F_SOFT_RESET       = BIT(14),
>  };
> 
>  struct spi_nor_read_command {
> diff --git a/drivers/mtd/spi-nor/sfdp.c b/drivers/mtd/spi-nor/sfdp.c
> index 7983ff431346..8e0741d8bfd3 100644
> --- a/drivers/mtd/spi-nor/sfdp.c
> +++ b/drivers/mtd/spi-nor/sfdp.c
> @@ -616,6 +616,10 @@ static int spi_nor_parse_bfpt(struct spi_nor *nor,
>                 break;
>         }
> 
> +       /* Soft Reset support. */
> +       if (bfpt.dwords[BFPT_DWORD(16)] & BFPT_DWORD16_SOFT_RST)

this can be improved. There are multiple reset methods described and you're
addressing just one of them.

> +               nor->flags |= SNOR_F_SOFT_RESET;
> +
>         /* Stop here if not JESD216 rev C or later. */
>         if (bfpt_header->length == BFPT_DWORD_MAX_JESD216B)
>                 return spi_nor_post_bfpt_fixups(nor, bfpt_header, &bfpt,
> diff --git a/drivers/mtd/spi-nor/sfdp.h b/drivers/mtd/spi-nor/sfdp.h
> index 6d7243067252..8ae55e98084e 100644
> --- a/drivers/mtd/spi-nor/sfdp.h
> +++ b/drivers/mtd/spi-nor/sfdp.h
> @@ -90,6 +90,8 @@ struct sfdp_bfpt {
>  #define BFPT_DWORD15_QER_SR2_BIT1_NO_RD                (0x4UL << 20)
>  #define BFPT_DWORD15_QER_SR2_BIT1              (0x5UL << 20) /* Spansion */
> 
> +#define BFPT_DWORD16_SOFT_RST                  BIT(12)
> +
>  #define BFPT_DWORD18_CMD_EXT_MASK              GENMASK(30, 29)
>  #define BFPT_DWORD18_CMD_EXT_REP               (0x0UL << 29) /* Repeat */
>  #define BFPT_DWORD18_CMD_EXT_INV               (0x1UL << 29) /* Invert */
> --
> 2.27.0
>