[PATCH 1/2] clk: Do not complain about correctly set read-only muxes when assigning clock parents from device tree

[PATCH 1/2] clk: Do not complain about correctly set read-only muxes when assigning clock parents from device tree

[Philipp Zabel]

Assigning a clock parent to a mux with the CLK_MUX_READ_ONLY flag causes an
error "clk: failed to reparent read_only_mux to already_set_parent: -38"
even if the hardware is already set to the correct parent clock.

This patch avoids the error message by checking whether the correct parent
is already set before calling clk_set_parent. This allows to use the
assigned-clock-parents device tree binding for clock muxes that are not
allowed to be changed anymore at the time of_clk_set_defaults is called.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 drivers/clk/clk-conf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
index aad4796..ca8dc86 100644
--- a/drivers/clk/clk-conf.c
+++ b/drivers/clk/clk-conf.c
@@ -62,7 +62,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
 			goto err;
 		}
 
-		rc = clk_set_parent(clk, pclk);
+		if (pclk != __clk_get_parent(clk))
+			rc = clk_set_parent(clk, pclk);
 		if (rc < 0)
 			pr_err("clk: failed to reparent %s to %s: %d\n",
 			       __clk_get_name(clk), __clk_get_name(pclk), rc);
-- 
2.1.3

[PATCH 1/2] clk: Do not complain about correctly set read-only muxes when assigning clock parents from device tree

[Shawn Guo]

On Mon, Dec 01, 2014 at 05:42:42PM +0100, Philipp Zabel wrote:
> Assigning a clock parent to a mux with the CLK_MUX_READ_ONLY flag causes an
> error "clk: failed to reparent read_only_mux to already_set_parent: -38"
> even if the hardware is already set to the correct parent clock.
> 
> This patch avoids the error message by checking whether the correct parent
> is already set before calling clk_set_parent. This allows to use the
> assigned-clock-parents device tree binding for clock muxes that are not
> allowed to be changed anymore at the time of_clk_set_defaults is called.
> 
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Philipp,

The patch should be sent to Mike Turquette <mturquette@linaro.org>.  The
patch itself makes sense to me, so

Acked-by: Shawn Guo <shawn.guo@linaro.org>

Shawn

> ---
>  drivers/clk/clk-conf.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
> index aad4796..ca8dc86 100644
> --- a/drivers/clk/clk-conf.c
> +++ b/drivers/clk/clk-conf.c
> @@ -62,7 +62,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
>  			goto err;
>  		}
>  
> -		rc = clk_set_parent(clk, pclk);
> +		if (pclk != __clk_get_parent(clk))
> +			rc = clk_set_parent(clk, pclk);
>  		if (rc < 0)
>  			pr_err("clk: failed to reparent %s to %s: %d\n",
>  			       __clk_get_name(clk), __clk_get_name(pclk), rc);
> -- 
> 2.1.3
> 

[PATCH 1/2] clk: Do not complain about correctly set read-only muxes when assigning clock parents from device tree

[Uwe Kleine-König]

Hello Philipp,

On Mon, Dec 01, 2014 at 05:42:42PM +0100, Philipp Zabel wrote:
> diff --git a/drivers/clk/clk-conf.c b/drivers/clk/clk-conf.c
> index aad4796..ca8dc86 100644
> --- a/drivers/clk/clk-conf.c
> +++ b/drivers/clk/clk-conf.c
> @@ -62,7 +62,8 @@ static int __set_clk_parents(struct device_node *node, bool clk_supplier)
>  			goto err;
>  		}
>  
> -		rc = clk_set_parent(clk, pclk);
> +		if (pclk != __clk_get_parent(clk))
> +			rc = clk_set_parent(clk, pclk);
>  		if (rc < 0)
>  			pr_err("clk: failed to reparent %s to %s: %d\n",
>  			       __clk_get_name(clk), __clk_get_name(pclk), rc);
I'd move the check for rc < 0 into the body of the if you introduced.
i.e.:

	if (pclk != __clk_get_parent(clk)) {
		rc = clk_set_parent(clk, pclk);
		if (rc < 0)
			...
	}

Semantically it doesn't make a difference because rc is zero when this
code is reached, but it makes it a bit clearer.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |