linux-kernel - Re: [RFC PATCH v2 03/12] mtd: spinand: perform controller tuning during probe

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Message-ID: <87tsvvgkks.fsf@bootlin.com>
Date: Thu, 05 Feb 2026 18:35:15 +0100
From: Miquel Raynal <miquel.raynal@...tlin.com>
To: Santhosh Kumar K <s-k6@...com>
Cc: <broonie@...nel.org>,  <robh@...nel.org>,  <krzk+dt@...nel.org>,
  <conor+dt@...nel.org>,  <richard@....at>,  <vigneshr@...com>,
  <tudor.ambarus@...aro.org>,  <pratyush@...nel.org>,  <mwalle@...nel.org>,
  <linux-spi@...r.kernel.org>,  <devicetree@...r.kernel.org>,
  <linux-kernel@...r.kernel.org>,  <linux-mtd@...ts.infradead.org>,
  <praneeth@...com>,  <u-kumar1@...com>,  <p-mantena@...com>,
  <a-dutta@...com>
Subject: Re: [RFC PATCH v2 03/12] mtd: spinand: perform controller tuning
 during probe

Hi Santhosh,

On 13/01/2026 at 19:46:08 +0530, Santhosh Kumar K <s-k6@...com> wrote:

> SPI controllers may need tuning for reliable high-speed operation.
> Without it, controllers use conservative timing that limits performance.
>
> Call spi_mem_execute_tuning() during probe to optimize timing for
> the device's read and write operations. Failures are non-fatal as
> controllers fall back to default timing.
>
> Signed-off-by: Santhosh Kumar K <s-k6@...com>
> ---
>  drivers/mtd/nand/spi/core.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/mtd/nand/spi/core.c b/drivers/mtd/nand/spi/core.c
> index 0346916b032b..2a45d1047736 100644
> --- a/drivers/mtd/nand/spi/core.c
> +++ b/drivers/mtd/nand/spi/core.c
> @@ -1658,6 +1658,7 @@ static int spinand_probe(struct spi_mem *mem)
>  {
>  	struct spinand_device *spinand;
>  	struct mtd_info *mtd;
> +	struct spi_mem_op read_op, write_op;
>  	int ret;
>  
>  	spinand = devm_kzalloc(&mem->spi->dev, sizeof(*spinand),
> @@ -1676,6 +1677,19 @@ static int spinand_probe(struct spi_mem *mem)
>  	if (ret)
>  		return ret;
>  
> +	read_op = *spinand->op_templates.read_cache;
> +	write_op = *spinand->op_templates.write_cache;

These will become:

 +	read_op = *spinand->op_templates->read_cache;
 +	write_op = *spinand->op_templates->write_cache;

after rebasing on nand/next or next -rc1.

> +
> +	ret = spi_mem_execute_tuning(mem, &read_op, &write_op);
> +	if (ret && ret != -EOPNOTSUPP) {
> +		dev_warn(&mem->spi->dev, "Failed to execute PHY tuning: %d\n",
> +			 ret);
> +		/*
> +		 * Tuning failure is non-fatal; the controller falls back to
> +		 * default timing, reducing speed but ensuring operation.
> +		 */
> +	}

Can we move the comment before spi_mem_execute_timing()? Then no more
brackets needed and it will be easier to read (imo).

LGTM otherwise.

Thanks,
Miquèl