Hi,
On Thu, 2015-09-03 at 16:17 +0200, marex@denx.de wrote:
On Thursday, September 03, 2015 at 03:41:59 PM, Chin Liang See wrote:
Ensuring spi_calibration is run when there is a change of sclk frequency. This will ensure the qspi flash access works for high sclk frequency
Signed-off-by: Chin Liang See clsee@altera.com Cc: Dinh Nguyen dinguyen@opensource.altera.com Cc: Dinh Nguyen dinh.linux@gmail.com Cc: Marek Vasut marex@denx.de Cc: Stefan Roese sr@denx.de Cc: Vikas Manocha vikas.manocha@st.com Cc: Jagannadh Teki jteki@openedev.com Cc: Pavel Machek pavel@denx.de
drivers/spi/cadence_qspi.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/spi/cadence_qspi.c b/drivers/spi/cadence_qspi.c index 34a0f46..300934e 100644 --- a/drivers/spi/cadence_qspi.c +++ b/drivers/spi/cadence_qspi.c @@ -37,7 +37,7 @@ static int cadence_spi_write_speed(struct udevice *bus, uint hz) }
/* Calibration sequence to determine the read data capture delay register */ -static int spi_calibration(struct udevice *bus) +static int spi_calibration(struct udevice *bus, uint hz) { struct cadence_spi_platdata *plat = bus->platdata; struct cadence_spi_priv *priv = dev_get_priv(bus); @@ -64,7 +64,7 @@ static int spi_calibration(struct udevice *bus) }
/* use back the intended clock and find low range */
- cadence_spi_write_speed(bus, plat->max_hz);
- cadence_spi_write_speed(bus, hz); for (i = 0; i < CQSPI_READ_CAPTURE_MAX_DELAY; i++) { /* Disable QSPI */ cadence_qspi_apb_controller_disable(base);
@@ -111,7 +111,7 @@ static int spi_calibration(struct udevice *bus) (range_hi + range_lo) / 2, range_lo, range_hi);
/* just to ensure we do once only when speed or chip select change */
- priv->qspi_calibrated_hz = plat->max_hz;
priv->qspi_calibrated_hz = hz; priv->qspi_calibrated_cs = spi_chip_select(bus);
return 0;
@@ -131,7 +131,7 @@ static int cadence_spi_set_speed(struct udevice *bus,
Hi,
My impression is that the logic here should be like this:
if (hz > plat->max_hz) { printf("error, freq. too high"); return -EINVAL; } if (priv->previous_hz != hz) /* Bus frequency changed, re-calibrate */ spi_calibrate(bus, hz) cadence_spi_write_speed(bus, priv->qspi_calibrated_hz); priv->previous_hz = hz;
Note that you need a new private variable, previous_hz, to hold the previous value of "hz". This is needed since the calibrated frequency might not be equal to requested frequency.
I know where you coming from. Yah, calibration can be skipped when requested frequency same as previous or calibrated one. Let me add that.
uint hz) /* Calibration required for different SCLK speed or chip select */ if (priv->qspi_calibrated_hz != plat->max_hz || priv->qspi_calibrated_cs != spi_chip_select(bus)) {
err = spi_calibration(bus);
err = spi_calibration(bus, hz);This is called after the frequency is configured in this function, this looks really backwards.
Yah, let me remove the old code.
Thanks Chin Liang
if (err) return err;}
Best regards, Marek Vasut