[PATCH 3.16.y-ckt 064/180] mmc: sunxi: Use devm_reset_control_get_optional() for reset control

[Luis Henriques]

3.16.7-ckt11 -stable review patch.  If anyone has any objections, please let me know.

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

From: Chen-Yu Tsai <wens at csie.org>

commit 9e71c589e44ddf2b86f361c81e360c6b0d0354b1 upstream.

The reset control for the sunxi mmc controller is optional. Some
newer platforms (sun6i, sun8i, sun9i) have it, while older ones
(sun4i, sun5i, sun7i) don't.

Use the properly stubbed _optional version so the driver does not
fail to compile when RESET_CONTROLLER=n.

This patch also adds a check for deferred probing on the reset
control.

Signed-off-by: Chen-Yu Tsai <wens at csie.org>
Acked-by: David Lanzendörfer <david.lanzendoerfer at o2s.ch>
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/mmc/host/sunxi-mmc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sunxi-mmc.c b/drivers/mmc/host/sunxi-mmc.c
index 024f67c98cdc..97823c68600a 100644
--- a/drivers/mmc/host/sunxi-mmc.c
+++ b/drivers/mmc/host/sunxi-mmc.c
@@ -909,7 +909,9 @@ static int sunxi_mmc_resource_request(struct sunxi_mmc_host *host,
 		return PTR_ERR(host->clk_mmc);
 	}
 
-	host->reset = devm_reset_control_get(&pdev->dev, "ahb");
+	host->reset = devm_reset_control_get_optional(&pdev->dev, "ahb");
+	if (PTR_ERR(host->reset) == -EPROBE_DEFER)
+		return PTR_ERR(host->reset);
 
 	ret = clk_prepare_enable(host->clk_ahb);
 	if (ret) {