linux-kernel - Re: 回信: [RFC PATCH 08/10] spi: mxic: Fix the transmit path

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Date:   Wed, 13 Oct 2021 15:04:15 +0800
From:   zhengxunli@...c.com.tw
To:     "Miquel Raynal" <miquel.raynal@...tlin.com>
Cc:     "Rob Herring" <robh+dt@...nel.org>,
        "Mark Brown" <broonie@...nel.org>,
        "Xiangsheng Hou" <Xiangsheng.Hou@...iatek.com>,
        "Boris Brezillon" <bbrezillon@...nel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        jaimeliao@...c.com.tw, juliensu@...c.com.tw,
        "Thomas Petazzoni" <thomas.petazzoni@...tlin.com>,
        "Miquel Raynal" <miquel.raynal@...tlin.com>,
        stable@...r.kernel.org, "Mason Yang" <masonccyang@...c.com.tw>,
        "Richard Weinberger" <richard@....at>,
        "Vignesh Raghavendra" <vigneshr@...com>,
        "Tudor Ambarus" <Tudor.Ambarus@...rochip.com>,
        <linux-mtd@...ts.infradead.org>, linux-spi@...r.kernel.org
Subject: Re: 回信: [RFC PATCH 08/10] spi: mxic: Fix the transmit path


> By working with external hardware ECC engines, we figured out that
> Under certain circumstances, it is needed for the SPI controller to
> check INT_TX_EMPTY and INT_RX_NOT_EMPTY in both receive and transmit
> path (not only in the receive path). The delay penalty being
> negligible, move this code in the common path.
> 
> Fixes: b942d80b0a39 ("spi: Add MXIC controller driver")
> Cc: stable@...r.kernel.org
> Suggested-by: Mason Yang <masonccyang@...c.com.tw>
> Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> ---
>  drivers/spi/spi-mxic.c | 28 ++++++++++++----------------
>  1 file changed, 12 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/spi/spi-mxic.c b/drivers/spi/spi-mxic.c
> index 96b418293bf2..4fb19e6f94b0 100644
> --- a/drivers/spi/spi-mxic.c
> +++ b/drivers/spi/spi-mxic.c
> @@ -304,25 +304,21 @@ static int mxic_spi_data_xfer(struct mxic_spi 
> *mxic, const void *txbuf,
> 
>        writel(data, mxic->regs + TXD(nbytes % 4));
> 
> +      ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
> +                sts & INT_TX_EMPTY, 0, USEC_PER_SEC);
> +      if (ret)
> +         return ret;
> +
> +      ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
> +                sts & INT_RX_NOT_EMPTY, 0,
> +                USEC_PER_SEC);
> +      if (ret)
> +         return ret;
> +
> +      data = readl(mxic->regs + RXD);
>        if (rxbuf) {
> -         ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
> -                   sts & INT_TX_EMPTY, 0,
> -                   USEC_PER_SEC);
> -         if (ret)
> -            return ret;
> -
> -         ret = readl_poll_timeout(mxic->regs + INT_STS, sts,
> -                   sts & INT_RX_NOT_EMPTY, 0,
> -                   USEC_PER_SEC);
> -         if (ret)
> -            return ret;
> -
> -         data = readl(mxic->regs + RXD);
>           data >>= (8 * (4 - nbytes));
>           memcpy(rxbuf + pos, &data, nbytes);
> -         WARN_ON(readl(mxic->regs + INT_STS) & INT_RX_NOT_EMPTY);
> -      } else {
> -         readl(mxic->regs + RXD);
>        }
>        WARN_ON(readl(mxic->regs + INT_STS) & INT_RX_NOT_EMPTY);
> 
> -- 
> 2.27.0
> 

Reviewed-by: Zhengxun Li <zhengxunli@...c.com.tw>


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