[PATCH 4.9 86/86] spi: imx: do not access registers while clocks disabled

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stefan Agner <ste...@agner.ch>

commit d593574aff0ab846136190b1729c151c736727ec upstream.

Since clocks are disabled except during message transfer clocks
are also disabled when spi_imx_remove gets called. Accessing
registers leads to a freeeze at least on a i.MX 6ULL. Enable
clocks before disabling accessing the MXC_CSPICTRL register.

Fixes: 9e556dcc55774 ("spi: spi-imx: only enable the clocks when we start to 
transfer a message")
Signed-off-by: Stefan Agner <ste...@agner.ch>
Signed-off-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/spi/spi-imx.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1307,12 +1307,23 @@ static int spi_imx_remove(struct platfor
 {
        struct spi_master *master = platform_get_drvdata(pdev);
        struct spi_imx_data *spi_imx = spi_master_get_devdata(master);
+       int ret;
 
        spi_bitbang_stop(&spi_imx->bitbang);
 
+       ret = clk_enable(spi_imx->clk_per);
+       if (ret)
+               return ret;
+
+       ret = clk_enable(spi_imx->clk_ipg);
+       if (ret) {
+               clk_disable(spi_imx->clk_per);
+               return ret;
+       }
+
        writel(0, spi_imx->base + MXC_CSPICTRL);
-       clk_unprepare(spi_imx->clk_ipg);
-       clk_unprepare(spi_imx->clk_per);
+       clk_disable_unprepare(spi_imx->clk_ipg);
+       clk_disable_unprepare(spi_imx->clk_per);
        spi_imx_sdma_exit(spi_imx);
        spi_master_put(master);