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

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Message-ID: <fc8d1ac0-c713-40ee-b818-47548f9d1818@ti.com>
Date: Sat, 7 Feb 2026 00:53:05 +0530
From: Santhosh Kumar K <s-k6@...com>
To: Miquel Raynal <miquel.raynal@...tlin.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>,
	<s-k6@...com>
Subject: Re: [RFC PATCH v2 03/12] mtd: spinand: perform controller tuning
 during probe

Hi Miquel,

On 05/02/26 23:05, Miquel Raynal wrote:
> 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.

Noted!

> 
>> +
>> +	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).

Yeah, I agree on the readability concern - will move them in v3.

Thanks,
Santhosh.

> 
> LGTM otherwise.
> 
> Thanks,
> Miquèl