linux-kernel - Re: [PATCH v10 08/17] mtd: spi-nor: core: use dummy cycle and address width info from SFDP

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Message-ID: <d4b5178e-debb-1397-caae-f20086f5c3fc@microchip.com>
Date:   Wed, 8 Jul 2020 16:03:47 +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 08/17] mtd: spi-nor: core: use dummy cycle and address
 width info from SFDP

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
> 
> The xSPI Profile 1.0 table specifies how many dummy cycles and address
> bytes are needed for the Read Status Register command in octal DTR mode.
> Use that information to send the correct Read SR command.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> ---
>  drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 7d24e63fcca8..f2748f1d9957 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -357,6 +357,8 @@ int spi_nor_write_disable(struct spi_nor *nor)
>  static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
>  {
>         int ret;
> +       u8 addr_bytes = nor->params->rdsr_addr_nbytes;
> +       u8 dummy = nor->params->rdsr_dummy;

no need to introduce local variables for a single dereference

> 
>         if (nor->spimem) {
>                 struct spi_mem_op op =
> @@ -365,10 +367,21 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
>                                    SPI_MEM_OP_NO_DUMMY,
>                                    SPI_MEM_OP_DATA_IN(1, sr, 1));
> 
> +               if (spi_nor_protocol_is_dtr(nor->reg_proto)) {
> +                       op.addr.nbytes = addr_bytes;
> +                       op.addr.val = 0;

isn't addr already initialized to 0?

> +                       op.dummy.nbytes = dummy;
> +               }
> +
> +               spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);
> +
>                 ret = spi_mem_exec_op(nor->spimem, &op);
>         } else {
> -               ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDSR,
> -                                                   sr, 1);
> +               if (spi_nor_protocol_is_dtr(nor->reg_proto))
> +                       ret = -ENOTSUPP;
> +               else
> +                       ret = nor->controller_ops->read_reg(nor, SPINOR_OP_RDSR,
> +                                                           sr, 1);
>         }

doesn't this belong to a previous patch?

> 
>         if (ret)
> @@ -388,6 +401,8 @@ static int spi_nor_read_sr(struct spi_nor *nor, u8 *sr)
>  static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr)
>  {
>         int ret;
> +       u8 addr_bytes = nor->params->rdsr_addr_nbytes;
> +       u8 dummy = nor->params->rdsr_dummy;
> 
>         if (nor->spimem) {
>                 struct spi_mem_op op =
> @@ -396,6 +411,12 @@ static int spi_nor_read_fsr(struct spi_nor *nor, u8 *fsr)
>                                    SPI_MEM_OP_NO_DUMMY,
>                                    SPI_MEM_OP_DATA_IN(1, fsr, 1));
> 
> +               if (spi_nor_protocol_is_dtr(nor->reg_proto)) {
> +                       op.addr.nbytes = addr_bytes;
> +                       op.addr.val = 0;
> +                       op.dummy.nbytes = dummy;
> +               }
> +
>                 spi_nor_spimem_setup_op(nor, &op, nor->reg_proto);
> 
>                 ret = spi_mem_exec_op(nor->spimem, &op);
> --
> 2.27.0
>