linux-kernel - Re: [PATCH v6 04/19] spi: spi-mem: allow specifying a command's extension

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Message-ID: <20200522182257.wneqsmfm22farzus@ti.com>
Date:   Fri, 22 May 2020 23:53:05 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     Boris Brezillon <boris.brezillon@...labora.com>
CC:     Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Matthias Brugger <matthias.bgg@...il.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>, Sekhar Nori <nsekhar@...com>,
        Mason Yang <masonccyang@...c.com.tw>
Subject: Re: [PATCH v6 04/19] spi: spi-mem: allow specifying a command's
 extension

Hi Boris,

On 21/05/20 08:22PM, Boris Brezillon wrote:
> On Wed, 20 May 2020 22:00:38 +0530
> Pratyush Yadav <p.yadav@...com> wrote:
> 
> As mentioned in one of my previous review, you should patch the mxic
> driver before extending the opcode field:
> 
> --->8---
> diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
> index 69491f3a515d..c3f4136a7c1d 100644
> --- a/drivers/spi/spi-mxic.c
> +++ b/drivers/spi/spi-mxic.c
> @@ -356,6 +356,7 @@ static int mxic_spi_mem_exec_op(struct spi_mem *mem,
>         int nio = 1, i, ret;
>         u32 ss_ctrl;
>         u8 addr[8];
> +       u8 cmd[2];

Regarding your comment about bisect-ability, how about I change this to:
  
  u8 cmd[sizeof(op->cmd.opcode)];

and put this patch before the change to 2-byte opcodes. This should also 
make it resistent to further changes in opcode size. Does that sound 
like a sane idea?
  
>         ret = mxic_spi_set_freq(mxic, mem->spi->max_speed_hz);
>         if (ret)
> @@ -393,7 +394,10 @@ static int mxic_spi_mem_exec_op(struct spi_mem *mem,
>         writel(readl(mxic->regs + HC_CFG) | HC_CFG_MAN_CS_ASSERT,
>                mxic->regs + HC_CFG);
>  
> -       ret = mxic_spi_data_xfer(mxic, &op->cmd.opcode, NULL, 1);
> +       for (i = 0; i < op->cmd.nbytes; i++)
> +               cmd[i] = op->cmd.opcode >> (8 * (op->cmd.nbytes - i - 1));
> +
> +       ret = mxic_spi_data_xfer(mxic, cmd, NULL, op->cmd.nbytes);
>         if (ret)
>                 goto out;
>  

-- 
Regards,
Pratyush Yadav
Texas Instruments India