Hello Russell,

On Sun, Mar 29, 2020 at 02:34:00PM +0100, Russell King - ARM Linux admin wrote:

On Sun, Mar 29, 2020 at 03:16:59PM +0200, Uwe Kleine-König wrote:

quoted

On Sun, Mar 29, 2020 at 11:48:09AM +0100, Russell King wrote:

quoted

diff --git a/drivers/gpio/gpio-mvebu.c b/drivers/gpio/gpio-mvebu.c
index fa5641615db6..ee13b11c5298 100644
--- a/drivers/gpio/gpio-mvebu.c
+++ b/drivers/gpio/gpio-mvebu.c

@@ -1132,6 +1132,9 @@ static int mvebu_gpio_probe(struct platform_device *pdev)
 	}
 
 	mvchip->clk = devm_clk_get(&pdev->dev, NULL);
+	if (mvchip->clk == ERR_PTR(-EPROBE_DEFER))
+		return -EPROBE_DEFER;
+
 	/* Not all SoCs require a clock.*/
 	if (!IS_ERR(mvchip->clk))
 		clk_prepare_enable(mvchip->clk);

I'd say the following is the right thing to do here:

	mvchip->clk = devm_clk_get_optional(...);
	if (IS_ERR(mvchip->clk))
		return ...

It's not that simple.  The clock is required for Armada 370, and is
optional for Armada 8040.

I'd say it is still the right approach here. On Armada 370 the dtb then
has a clk and on Armada 8040 it doesn't. So if with
devm_clk_get_optional() something goes wrong that's because the dtb is
wrong. And in fact the handling is even better than with your suggested
patch as every error (but EPROBE_DEFER) is ignored instead of passed to
the caller with your (and the existing) approach.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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