spi: imx: do not access registers while clocks disabled

commit d593574 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: 9e556dc ("spi: spi-imx: only enable the clocks when we start to transfer a message")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/spi/spi-imx.c

@@ -1220,12 +1220,23 @@ static int spi_imx_remove(struct platform_device *pdev)
 {
 	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);