linux-kernel - [PATCH RESEND v2] clk: probe defer when clock not yet ready

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Message-ID: <20131125194704.5a5922b7@armhf>
Date:	Mon, 25 Nov 2013 19:47:04 +0100
From:	Jean-Francois Moine <moinejf@...e.fr>
To:	linux-kernel@...r.kernel.org
Cc:	Mark Brown <broonie@...nel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Mike Turquette <mturquette@...aro.org>,
	Russell King <linux@....linux.org.uk>
Subject: [PATCH RESEND v2] clk: probe defer when clock not yet ready

At probe time, a clock device may not be ready when some other device
wants to use it. 

This patch lets the functions clk_get/devm_clk_get return a probe defer
when the clock is defined in the DT but not yet available.

It also fixes an erroneous call to clk_get_sys() when __clk_get() fails.

Signed-off-by: Jean-Francois Moine <moinejf@...e.fr>
---
resend v2: remove ASoc from subject (thank you, Mark)
resend: - patch subject change from
   [PATCH v3 1/2] ASoC: kirkwood: clk: probe defer when clock not yet ready
	- base kernel 3.13.0-rc1
v2: fix __clk_get() failure (from Russell King)
---
 drivers/clk/clk.c    | 2 +-
 drivers/clk/clkdev.c | 7 ++++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 2cf2ea6..41361c6 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2187,7 +2187,7 @@ EXPORT_SYMBOL_GPL(of_clk_del_provider);
 struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec)
 {
 	struct of_clk_provider *provider;
-	struct clk *clk = ERR_PTR(-ENOENT);
+	struct clk *clk = ERR_PTR(-EPROBE_DEFER);
 
 	/* Check if we have such a provider in our array */
 	mutex_lock(&of_clk_lock);
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c
index 442a313..1f402b9 100644
--- a/drivers/clk/clkdev.c
+++ b/drivers/clk/clkdev.c
@@ -157,7 +157,12 @@ struct clk *clk_get(struct device *dev, const char *con_id)
 
 	if (dev) {
 		clk = of_clk_get_by_name(dev->of_node, con_id);
-		if (!IS_ERR(clk) && __clk_get(clk))
+		if (!IS_ERR(clk)) {
+			if (!__clk_get(clk))
+				clk = ERR_PTR(-ENOENT);
+			return clk;
+		}
+		if (PTR_ERR(clk) == -EPROBE_DEFER)
 			return clk;
 	}
 
-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
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