Unverified Commit f43579ef authored by Haibo Chen's avatar Haibo Chen Committed by Mark Brown
Browse files

spi: spi-nxp-fspi: limit the clock rate for different sample clock source selection 

For different sample clock source selection, the max frequency
flexspi supported are different. For mode 0, max frequency is 66MHz.
For mode 3, the max frequency is 166MHz.

Refer to 3.9.9 FlexSPI timing parameters on page 65.
https://www.nxp.com/docs/en/data-sheet/IMX8MNCEC.pdf



Though flexspi maybe still work under higher frequency, but can't
guarantee the stability. IC suggest to add this limitation on all
SoCs which contain flexspi.

Fixes: c07f2703 ("spi: spi-nxp-fspi: add the support for sample data from DQS pad")
Signed-off-by: default avatarHaibo Chen <haibo.chen@nxp.com>
Link: https://patch.msgid.link/20250922-fspi-fix-v1-3-ff4315359d31@nxp.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent b93b4269

drivers/spi/spi-nxp-fspi.c

+8 −2
Original line number Diff line number Diff line
@@ -406,6 +406,8 @@ struct nxp_fspi { 
	int flags;

	/* save the previous operation clock rate */

	unsigned long pre_op_rate;

	/* the max clock rate fspi output to device */

	unsigned long max_rate;

};



static inline int needs_ip_only(struct nxp_fspi *f)
@@ -687,10 +689,13 @@ static void nxp_fspi_select_rx_sample_clk_source(struct nxp_fspi *f, 
	 * change the mode back to mode 0.

	 */

	reg = fspi_readl(f, f->iobase + FSPI_MCR0);

	if (op_is_dtr)

	if (op_is_dtr) {

		reg |= FSPI_MCR0_RXCLKSRC(3);

	else	/*select mode 0 */

		f->max_rate = 166000000;

	} else {	/*select mode 0 */

		reg &= ~FSPI_MCR0_RXCLKSRC(3);

		f->max_rate = 66000000;

	}

	fspi_writel(f, reg, f->iobase + FSPI_MCR0);

}
@@ -816,6 +821,7 @@ static void nxp_fspi_select_mem(struct nxp_fspi *f, struct spi_device *spi, 
	dev_dbg(f->dev, "Target device [CS:%x] selected\n", spi_get_chipselect(spi, 0));



	nxp_fspi_select_rx_sample_clk_source(f, op_is_dtr);

	rate = min(f->max_rate, op->max_freq);



	if (op_is_dtr) {

		f->flags |= FSPI_DTR_MODE;