spi: dw: fix wrong BAUDR setting after resume

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>
Link: https://patch.msgid.link/20260612002835.5240-1-jszhang@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-dw.h b/drivers/spi/spi-dw.h
index 9cc79c566a70c0ababf01cc73111c14d73a35a98..2f2debc64e7377f1a39b7732692dc0b06beb0897 100644 (file)
--- 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);