[PATCH] spi: dw: fix wrong BAUDR setting after resume

[Jisheng Zhang <jszhang@kernel.org>]

After resuming from suspend to ram, spi transfer stops working. Further
debugging shows that the BAUDR register isn't correctly set, this is
due to dws->current_freq doesn't match the HW BAUDR setting,
specifically, the dws->current_freq equals to speed_hz, but BAUDR is 0.
so the dw_spi_set_clk() in below code won't be called:

        if (dws->current_freq != speed_hz) {
                dw_spi_set_clk(dws, clk_div);
                dws->current_freq = speed_hz;
        }

The mismatch comes from dw_spi_shutdown_chip() when suspending.
Fix this mismatch by setting dws->current_freq to 0 as well when
clearing BAUDR reg in dw_spi_shutdown_chip().

Fixes: e24c74527207 ("spi: controller driver for Designware SPI core")
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
 drivers/spi/spi-dw.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 9cc79c566a70..2f2debc64e73 100644
--- a/drivers/spi/spi-dw.h
+++ b/drivers/spi/spi-dw.h
@@ -282,6 +282,7 @@ static inline void dw_spi_shutdown_chip(struct dw_spi *dws)
 {
 	dw_spi_enable_chip(dws, 0);
 	dw_spi_set_clk(dws, 0);
+	dws->current_freq = 0;
 }
 
 extern void dw_spi_set_cs(struct spi_device *spi, bool enable);
-- 
2.51.0