zynq_qspi.c: Set correct frequency regardless of hardware setting

The QSPI frequency set by the ROM may not be using the 1/2 clock divider,
examining the E000D000 register at boot reveils it's usually set to 1/4.
The driver always assumes it is set at 1/2 at boot, so it does not program
the clock rate if the requested frequency happens to match that.

This results in the QSPI clock running at 50MHz when 100MHz was requested.

To fix, set the current rate of the master (speed_hz) to "0" at startup, so
that the driver always programs the clock divider the first time the
zynq_qspi_setup_transfer method is called. This assures that the QSPI is
actually running at the requested clock rate.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Mike Looijmans <mike.looijmans@topic.nl>

diff --git a/drivers/spi/zynq_qspi.c b/drivers/spi/zynq_qspi.c
index 818267d7ec498c99c157dc251fb8eaf607a5b458..215b26f6c9783708bc89f113aad692217264e42e 100644 (file)
--- a/drivers/spi/zynq_qspi.c
+++ b/drivers/spi/zynq_qspi.c
@@ -817,9 +817,8 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
        qspi->slave.dio = is_dio;
        qspi->slave.op_mode_rx = SPI_OPM_RX_QOF;
        qspi->slave.op_mode_tx = SPI_OPM_TX_QPP;
-       qspi->qspi.master.speed_hz = qspi->qspi.master.input_clk_hz / 2;
-       qspi->qspi.max_speed_hz = (max_hz < qspi->qspi.master.speed_hz) ?
-                                                               max_hz : qspi->qspi.master.speed_hz;
+       lqspi_frequency = qspi->qspi.master.input_clk_hz / 2;
+       qspi->qspi.max_speed_hz = min(max_hz, lqspi_frequency);
        qspi->qspi.master.is_dio = is_dio;
        qspi->qspi.master.is_dual = is_dual;
        qspi->qspi.mode = mode;