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Message-ID: <ceaf4036-12f8-0cfe-9cdc-37d2ef96bd76@ti.com>
Date:   Mon, 31 Oct 2022 20:12:55 +0530
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Subject: Re: [EXTERNAL] [PATCH] mtd: spi-nor: Fix the number of bytes for the
 dummy cycles
To:     Allen-KH Cheng <allen-kh.cheng@mediatek.com>,
        Tudor Ambarus <tudor.ambarus@microchip.com>,
        Pratyush Yadav <pratyush@kernel.org>,
        Michael Walle <michael@walle.cc>,
        Miquel Raynal <miquel.raynal@bootlin.com>,
        Richard Weinberger <richard@nod.at>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        <linux-mtd@lists.infradead.org>
CC:     <linux-spi@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-mediatek@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <Project_Global_Chrome_Upstream_Group@mediatek.com>,
        Bayi Cheng <bayi.cheng@mediatek.com>
References: <20221031124633.13189-1-allen-kh.cheng@mediatek.com>
Content-Language: en-US
From:   Dhruva Gole <d-gole@ti.com>
In-Reply-To: <20221031124633.13189-1-allen-kh.cheng@mediatek.com>
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On 31/10/22 18:16, Allen-KH Cheng wrote:
> The number of bytes used by spi_nor_spimem_check_readop() may be
> incorrect for the dummy cycles. Since nor->read_dummy is not initialized
> before spi_nor_spimem_adjust_hwcaps().
>
> We use both mode and wait state clock cycles instead of nor->read_dummy.
>
> Fixes: 0e30f47232ab ("mtd: spi-nor: add support for DTR protocol")
> Co-developed-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
> Signed-off-by: Allen-KH Cheng <allen-kh.cheng@mediatek.com>
> ---

Tested-by: Dhruva Gole <d-gole@ti.com>

>   drivers/mtd/spi-nor/core.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 6c921eb3fadb..8b9c318a0ad4 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1914,7 +1914,8 @@ static int spi_nor_spimem_check_readop(struct spi_nor *nor,
>   	spi_nor_spimem_setup_op(nor, &op, read->proto);
>   
>   	/* convert the dummy cycles to the number of bytes */
> -	op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
> +	op.dummy.nbytes = (read->num_mode_clocks + read->num_wait_states) *
> +			  op.dummy.buswidth / 8;
>   	if (spi_nor_protocol_is_dtr(nor->read_proto))
>   		op.dummy.nbytes *= 2;
>   
Tested on my AM625 SK EVM having spi nor flash and no obvious 
regressions observed :)

-- 
Best regards,
Dhruva Gole
Texas Instruments Incorporated