spi/rockchip: fix bug that case spi can't go as fast as slave request
Because the minimum divisor in rk3x's spi controller is 2,
if spi_clk is less than 2 * sclk_out, we can't get the right divisor.
So we must set spi_clk again to match slave request.
Signed-off-by: Addy Ke <addy.ke@rock-chips.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index f96ea8a..3044c6c 100644
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -145,6 +145,9 @@
#define RXBUSY (1 << 0)
#define TXBUSY (1 << 1)
+/* sclk_out: spi master internal logic in rk3x can support 50Mhz */
+#define MAX_SCLK_OUT 50000000
+
enum rockchip_ssi_type {
SSI_MOTO_SPI = 0,
SSI_TI_SSP,
@@ -496,6 +499,15 @@
dmacr |= RF_DMA_EN;
}
+ if (WARN_ON(rs->speed > MAX_SCLK_OUT))
+ rs->speed = MAX_SCLK_OUT;
+
+ /* the minimum divsor is 2 */
+ if (rs->max_freq < 2 * rs->speed) {
+ clk_set_rate(rs->spiclk, 2 * rs->speed);
+ rs->max_freq = clk_get_rate(rs->spiclk);
+ }
+
/* div doesn't support odd number */
div = max_t(u32, rs->max_freq / rs->speed, 1);
div = (div + 1) & 0xfffe;