spi: spi-mxs: Don't set clock for each xfer

[karo-tx-linux.git] / drivers / spi / spi-mxs.c

diff --git a/drivers/spi/spi-mxs.c b/drivers/spi/spi-mxs.c
index 9e6101a38e8548d7562509b0cd32e279a4717ba9..759de701f050aa7453fb741158d73beeda4688e0 100644 (file)
--- a/drivers/spi/spi-mxs.c
+++ b/drivers/spi/spi-mxs.c
@@ -67,6 +67,7 @@
 struct mxs_spi {
        struct mxs_ssp          ssp;
        struct completion       c;
+       unsigned int            sck;    /* Rate requested (vs actual) */
 };
 
 static int mxs_spi_setup_transfer(struct spi_device *dev,
@@ -81,7 +82,19 @@ static int mxs_spi_setup_transfer(struct spi_device *dev,
                return -EINVAL;
        }
 
-       mxs_ssp_set_clk_rate(ssp, hz);
+       if (hz != spi->sck) {
+               mxs_ssp_set_clk_rate(ssp, hz);
+               /*
+                * Save requested rate, hz, rather than the actual rate,
+                * ssp->clk_rate.  Otherwise we would set the rate every trasfer
+                * when the actual rate is not quite the same as requested rate.
+                */
+               spi->sck = hz;
+               /*
+                * Perhaps we should return an error if the actual clock is
+                * nowhere close to what was requested?
+                */
+       }
 
        writel(BM_SSP_CTRL0_LOCK_CS,
                ssp->base + HW_SSP_CTRL0 + STMP_OFFSET_REG_SET);