Re: [PATCH RFC 6/7] spi: spi-mem: Call spi_set_rx_sampling_point() for each op

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: Frieder Schrempf <frieder@fris.de>
Cc: Mark Brown <broonie@kernel.org>,
	 Richard Weinberger <richard@nod.at>,
	Vignesh Raghavendra <vigneshr@ti.com>,  Han Xu <han.xu@nxp.com>,
	Eberhard Stoll <eberhard.stoll@kontron.de>,
	 Frieder Schrempf <frieder.schrempf@kontron.de>,
	 Tudor Ambarus <tudor.ambarus@linaro.org>,
	Pratyush Yadav <pratyush@kernel.org>,
	 Michael Walle <mwalle@kernel.org>,
	linux-spi@vger.kernel.org,  linux-kernel@vger.kernel.org,
	linux-mtd@lists.infradead.org,  imx@lists.linux.dev
Subject: Re: [PATCH RFC 6/7] spi: spi-mem: Call spi_set_rx_sampling_point() for each op
Date: Mon, 09 Mar 2026 16:09:34 +0100	[thread overview]
Message-ID: <87wlzlnioh.fsf@bootlin.com> (raw)
In-Reply-To: <20260303-fsl-qspi-rx-sampling-delay-v1-6-9326bbc492d6@kontron.de> (Frieder Schrempf's message of "Tue, 03 Mar 2026 17:29:27 +0100")

Hi Frieder,

First, thanks for the series! I believe it will conflict with the SPI
tuning series as you mentioned, but we should be able to make them live
side by side.

On 03/03/2026 at 17:29:27 +01, Frieder Schrempf <frieder@fris.de> wrote:

> From: Frieder Schrempf <frieder.schrempf@kontron.de>
>
> With clock rates changing on a per-op basis, we need to make sure
> that we meet the RX sampling point delay constraint of the underlying
> SPI chip.
>
> Signed-off-by: Frieder Schrempf <frieder.schrempf@kontron.de>
> ---
>  drivers/spi/spi-mem.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> index a09371a075d2e..6b8bee7d6f5e3 100644
> --- a/drivers/spi/spi-mem.c
> +++ b/drivers/spi/spi-mem.c
> @@ -589,6 +589,8 @@ void spi_mem_adjust_op_freq(struct spi_mem *mem, struct spi_mem_op *op)
>  {
>  	if (!op->max_freq || op->max_freq > mem->spi->max_speed_hz)
>  		op->max_freq = mem->spi->max_speed_hz;
> +
> +	op->max_freq = spi_set_rx_sampling_point(mem->spi,
> op->max_freq);

How can this work with the above 2 lines? Maybe there will be the need
to use a "min of the max" frequencies?

Thanks,
Miquèl