If the device tree provides a read delay value, use that directly and do not perform the calibration procedure.
This allows the device tree to over-ride the read delay value in cases where the read delay value obtained via calibration is incorrect. One such example is the Cypress Semper flash. It needs a read delay of 4 in octal DTR mode. But since the calibration procedure is run before the flash is switched in octal DTR mode, it yields a read delay of 2. A value of 4 works for both octal DTR and legacy modes.
Signed-off-by: Pratyush Yadav p.yadav@ti.com --- drivers/spi/cadence_qspi.c | 26 +++++++++++++++++++++----- drivers/spi/cadence_qspi.h | 1 + 2 files changed, 22 insertions(+), 5 deletions(-)
diff --git a/drivers/spi/cadence_qspi.c b/drivers/spi/cadence_qspi.c index 1e85749209..305f2ec0df 100644 --- a/drivers/spi/cadence_qspi.c +++ b/drivers/spi/cadence_qspi.c @@ -141,12 +141,20 @@ static int cadence_spi_set_speed(struct udevice *bus, uint hz) cadence_qspi_apb_controller_disable(priv->regbase);
/* - * Calibration required for different current SCLK speed, requested - * SCLK speed or chip select + * If the device tree already provides a read delay value, use that + * instead of calibrating. */ - if (priv->previous_hz != hz || - priv->qspi_calibrated_hz != hz || - priv->qspi_calibrated_cs != spi_chip_select(bus)) { + if (plat->read_delay >= 0) { + cadence_spi_write_speed(bus, hz); + cadence_qspi_apb_readdata_capture(priv->regbase, 1, + plat->read_delay); + } else if (priv->previous_hz != hz || + priv->qspi_calibrated_hz != hz || + priv->qspi_calibrated_cs != spi_chip_select(bus)) { + /* + * Calibration required for different current SCLK speed, + * requested SCLK speed or chip select + */ err = spi_calibration(bus, hz); if (err) return err; @@ -320,6 +328,14 @@ static int cadence_spi_ofdata_to_platdata(struct udevice *bus) 255); plat->tchsh_ns = ofnode_read_u32_default(subnode, "cdns,tchsh-ns", 20); plat->tslch_ns = ofnode_read_u32_default(subnode, "cdns,tslch-ns", 20); + /* + * Read delay should be an unsigned value but we use a signed integer + * so that negative values can indicate that the device tree did not + * specify any signed values and we need to perform the calibration + * sequence to find it out. + */ + plat->read_delay = ofnode_read_s32_default(subnode, "cdns,read-delay", + -1);
debug("%s: regbase=%p ahbbase=%p max-frequency=%d page-size=%d\n", __func__, plat->regbase, plat->ahbbase, plat->max_hz, diff --git a/drivers/spi/cadence_qspi.h b/drivers/spi/cadence_qspi.h index ae459c74a1..9dff2fdced 100644 --- a/drivers/spi/cadence_qspi.h +++ b/drivers/spi/cadence_qspi.h @@ -26,6 +26,7 @@ struct cadence_spi_platdata { u32 trigger_address; fdt_addr_t ahbsize; bool use_dac_mode; + int read_delay;
/* Flash parameters */ u32 page_size;