linux-kernel - Re: [RFC PATCH 3/6] mtd: spi-nor: core: run calibration when initialization is done

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Message-ID: <20220517160226.4107f282@xps-13>
Date:   Tue, 17 May 2022 16:02:26 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Pratyush Yadav <p.yadav@...com>
Cc:     Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Tudor Ambarus <tudor.ambarus@...rochip.com>,
        Michael Walle <michael@...le.cc>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Mark Brown <broonie@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-mtd@...ts.infradead.org>, <linux-spi@...r.kernel.org>,
        Lokesh Vutla <lokeshvutla@...com>
Subject: Re: [RFC PATCH 3/6] mtd: spi-nor: core: run calibration when
 initialization is done

Hi Pratyush,

p.yadav@...com wrote on Fri, 12 Mar 2021 00:42:13 +0530:

> Once the flash is initialized tell the controller it can run
> calibration procedures if needed. This can be useful when calibration is
> needed to run at higher clock speeds.
> 
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
> ---
>  drivers/mtd/spi-nor/core.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 88888df009f0..e0cbcaf1be89 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -3650,6 +3650,7 @@ static int spi_nor_probe(struct spi_mem *spimem)
>  	 * checking what's really supported using spi_mem_supports_op().
>  	 */
>  	const struct spi_nor_hwcaps hwcaps = { .mask = SNOR_HWCAPS_ALL };
> +	struct spi_mem_op op;
>  	char *flash_name;
>  	int ret;
>  
> @@ -3709,8 +3710,15 @@ static int spi_nor_probe(struct spi_mem *spimem)
>  	if (ret)
>  		return ret;
>  
> -	return mtd_device_register(&nor->mtd, data ? data->parts : NULL,
> -				   data ? data->nr_parts : 0);
> +	ret = mtd_device_register(&nor->mtd, data ? data->parts : NULL,
> +				  data ? data->nr_parts : 0);
> +	if (ret)
> +		return ret;
> +
> +	op = spi_nor_spimem_get_read_op(nor);

Isn't this too specific? I really don't know much about spi-nors, but I
find odd to have this op being created here, why not moving this into
the _do_calibration() helper?

> +	spi_mem_do_calibration(nor->spimem, &op);

A warning/info upon calibration error (not on the absence of the hook)
would be nice?

> +
> +	return 0;
>  }
>  
>  static int spi_nor_remove(struct spi_mem *spimem)

Otherwise I like the overall idea.

Thanks,
Miquèl