6.17-stable review patch. If anyone has any objections, please let me know.
------------------
From: Haibo Chen haibo.chen@nxp.com
[ Upstream commit c07f270323175b83779c2c2b80b360ed476baec5 ]
flexspi define four mode for sample clock source selection. Here is the list of modes: mode 0: Dummy Read strobe generated by FlexSPI Controller and loopback internally mode 1: Dummy Read strobe generated by FlexSPI Controller and loopback from DQS pad mode 2: Reserved mode 3: Flash provided Read strobe and input from DQS pad
In default, flexspi use mode 0 after reset. And for DTR mode, flexspi only support 8D-8D-8D mode. For 8D-8D-8D mode, IC suggest to use mode 3, otherwise read always get incorrect data.
For DTR mode, flexspi will automatically div 2 of the root clock and output to device. the formula is: device_clock = root_clock / (is_dtr ? 2 : 1) So correct the clock rate setting for DTR mode to get the max performance.
Signed-off-by: Haibo Chen haibo.chen@nxp.com Reviewed-by: Frank Li Frank.Li@nxp.com Link: https://patch.msgid.link/20250917-flexspi-ddr-v2-4-bb9fe2a01889@nxp.com Signed-off-by: Mark Brown broonie@kernel.org Stable-dep-of: a89103f67112 ("spi: spi-nxp-fspi: re-config the clock rate when operation require new clock rate") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-nxp-fspi.c | 56 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 53 insertions(+), 3 deletions(-)
diff --git a/drivers/spi/spi-nxp-fspi.c b/drivers/spi/spi-nxp-fspi.c index b92bfef47371f..7cbe774f1f39b 100644 --- a/drivers/spi/spi-nxp-fspi.c +++ b/drivers/spi/spi-nxp-fspi.c @@ -399,7 +399,8 @@ struct nxp_fspi { struct mutex lock; struct pm_qos_request pm_qos_req; int selected; -#define FSPI_NEED_INIT (1 << 0) +#define FSPI_NEED_INIT BIT(0) +#define FSPI_DTR_MODE BIT(1) int flags; };
@@ -645,6 +646,40 @@ static void nxp_fspi_clk_disable_unprep(struct nxp_fspi *f) return; }
+/* + * Sample Clock source selection for Flash Reading + * Four modes defined by fspi: + * mode 0: Dummy Read strobe generated by FlexSPI Controller + * and loopback internally + * mode 1: Dummy Read strobe generated by FlexSPI Controller + * and loopback from DQS pad + * mode 2: Reserved + * mode 3: Flash provided Read strobe and input from DQS pad + * + * fspi default use mode 0 after reset + */ +static void nxp_fspi_select_rx_sample_clk_source(struct nxp_fspi *f, + bool op_is_dtr) +{ + u32 reg; + + /* + * For 8D-8D-8D mode, need to use mode 3 (Flash provided Read + * strobe and input from DQS pad), otherwise read operaton may + * meet issue. + * This mode require flash device connect the DQS pad on board. + * For other modes, still use mode 0, keep align with before. + * spi_nor_suspend will disable 8D-8D-8D mode, also need to + * change the mode back to mode 0. + */ + reg = fspi_readl(f, f->iobase + FSPI_MCR0); + if (op_is_dtr) + reg |= FSPI_MCR0_RXCLKSRC(3); + else /*select mode 0 */ + reg &= ~FSPI_MCR0_RXCLKSRC(3); + fspi_writel(f, reg, f->iobase + FSPI_MCR0); +} + static void nxp_fspi_dll_calibration(struct nxp_fspi *f) { int ret; @@ -715,15 +750,18 @@ static void nxp_fspi_dll_calibration(struct nxp_fspi *f) static void nxp_fspi_select_mem(struct nxp_fspi *f, struct spi_device *spi, const struct spi_mem_op *op) { + /* flexspi only support one DTR mode: 8D-8D-8D */ + bool op_is_dtr = op->cmd.dtr && op->addr.dtr && op->dummy.dtr && op->data.dtr; unsigned long rate = op->max_freq; int ret; uint64_t size_kb;
/* * Return, if previously selected target device is same as current - * requested target device. + * requested target device. Also the DTR or STR mode do not change. */ - if (f->selected == spi_get_chipselect(spi, 0)) + if ((f->selected == spi_get_chipselect(spi, 0)) && + (!!(f->flags & FSPI_DTR_MODE) == op_is_dtr)) return;
/* Reset FLSHxxCR0 registers */ @@ -740,6 +778,18 @@ 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); + + if (op_is_dtr) { + f->flags |= FSPI_DTR_MODE; + /* For DTR mode, flexspi will default div 2 and output to device. + * so here to config the root clock to 2 * device rate. + */ + rate = rate * 2; + } else { + f->flags &= ~FSPI_DTR_MODE; + } + nxp_fspi_clk_disable_unprep(f);
ret = clk_set_rate(f->clk, rate);