[PATCH] clk: at91: fix possible dead lock in new drivers

[PATCH] clk: at91: fix possible dead lock in new drivers

[Ahmad Fatoum]

syscon_node_to_regmap() will make the created regmap get and enable the
first clock it can parse from the device tree. This clock is not needed to
access the registers and should not be enabled at that time.

Use device_node_to_regmap to resolve this as it looks up the regmap in
the same list but doesn't care about the clocks. This issue is detected
by lockdep when booting the sama5d3 with a device tree containing the
new clk bindings.

This fix already happened in 6956eb33abb5 ("clk: at91: fix possible
deadlock") for the drivers that had been migrated to the new clk binding
back then. This does the same for the new drivers as well.

Fixes: 01e2113de9a5 ("clk: at91: add sam9x60 pmc driver")
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
Only boot tested on the sama5d3.
---
 drivers/clk/at91/at91sam9g45.c | 2 +-
 drivers/clk/at91/at91sam9n12.c | 2 +-
 drivers/clk/at91/sam9x60.c     | 2 +-
 drivers/clk/at91/sama5d3.c     | 2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/at91/at91sam9g45.c b/drivers/clk/at91/at91sam9g45.c
index 9873b583c260..fe9d391adeba 100644
--- a/drivers/clk/at91/at91sam9g45.c
+++ b/drivers/clk/at91/at91sam9g45.c
@@ -111,7 +111,7 @@ static void __init at91sam9g45_pmc_setup(struct device_node *np)
 		return;
 	mainxtal_name = of_clk_get_parent_name(np, i);
 
-	regmap = syscon_node_to_regmap(np);
+	regmap = device_node_to_regmap(np);
 	if (IS_ERR(regmap))
 		return;
 
diff --git a/drivers/clk/at91/at91sam9n12.c b/drivers/clk/at91/at91sam9n12.c
index 630dc5d87171..4aa97e672bd6 100644
--- a/drivers/clk/at91/at91sam9n12.c
+++ b/drivers/clk/at91/at91sam9n12.c
@@ -124,7 +124,7 @@ static void __init at91sam9n12_pmc_setup(struct device_node *np)
 		return;
 	mainxtal_name = of_clk_get_parent_name(np, i);
 
-	regmap = syscon_node_to_regmap(np);
+	regmap = device_node_to_regmap(np);
 	if (IS_ERR(regmap))
 		return;
 
diff --git a/drivers/clk/at91/sam9x60.c b/drivers/clk/at91/sam9x60.c
index 3e20aa68259f..2b4c67485eee 100644
--- a/drivers/clk/at91/sam9x60.c
+++ b/drivers/clk/at91/sam9x60.c
@@ -178,7 +178,7 @@ static void __init sam9x60_pmc_setup(struct device_node *np)
 		return;
 	mainxtal_name = of_clk_get_parent_name(np, i);
 
-	regmap = syscon_node_to_regmap(np);
+	regmap = device_node_to_regmap(np);
 	if (IS_ERR(regmap))
 		return;
 
diff --git a/drivers/clk/at91/sama5d3.c b/drivers/clk/at91/sama5d3.c
index 5e4e44dd4c37..5609b04e6565 100644
--- a/drivers/clk/at91/sama5d3.c
+++ b/drivers/clk/at91/sama5d3.c
@@ -121,7 +121,7 @@ static void __init sama5d3_pmc_setup(struct device_node *np)
 		return;
 	mainxtal_name = of_clk_get_parent_name(np, i);
 
-	regmap = syscon_node_to_regmap(np);
+	regmap = device_node_to_regmap(np);
 	if (IS_ERR(regmap))
 		return;
 
-- 
2.27.0

Re: [PATCH] clk: at91: fix possible dead lock in new drivers

[Alexandre Belloni]

On 03/07/2020 09:32:35+0200, Ahmad Fatoum wrote:
> syscon_node_to_regmap() will make the created regmap get and enable the
> first clock it can parse from the device tree. This clock is not needed to
> access the registers and should not be enabled at that time.
> 
> Use device_node_to_regmap to resolve this as it looks up the regmap in
> the same list but doesn't care about the clocks. This issue is detected
> by lockdep when booting the sama5d3 with a device tree containing the
> new clk bindings.
> 
> This fix already happened in 6956eb33abb5 ("clk: at91: fix possible
> deadlock") for the drivers that had been migrated to the new clk binding
> back then. This does the same for the new drivers as well.
> 
> Fixes: 01e2113de9a5 ("clk: at91: add sam9x60 pmc driver")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
> Only boot tested on the sama5d3.
> ---
>  drivers/clk/at91/at91sam9g45.c | 2 +-
>  drivers/clk/at91/at91sam9n12.c | 2 +-
>  drivers/clk/at91/sam9x60.c     | 2 +-
>  drivers/clk/at91/sama5d3.c     | 2 +-
>  4 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/at91/at91sam9g45.c b/drivers/clk/at91/at91sam9g45.c
> index 9873b583c260..fe9d391adeba 100644
> --- a/drivers/clk/at91/at91sam9g45.c
> +++ b/drivers/clk/at91/at91sam9g45.c
> @@ -111,7 +111,7 @@ static void __init at91sam9g45_pmc_setup(struct device_node *np)
>  		return;
>  	mainxtal_name = of_clk_get_parent_name(np, i);
>  
> -	regmap = syscon_node_to_regmap(np);
> +	regmap = device_node_to_regmap(np);
>  	if (IS_ERR(regmap))
>  		return;
>  
> diff --git a/drivers/clk/at91/at91sam9n12.c b/drivers/clk/at91/at91sam9n12.c
> index 630dc5d87171..4aa97e672bd6 100644
> --- a/drivers/clk/at91/at91sam9n12.c
> +++ b/drivers/clk/at91/at91sam9n12.c
> @@ -124,7 +124,7 @@ static void __init at91sam9n12_pmc_setup(struct device_node *np)
>  		return;
>  	mainxtal_name = of_clk_get_parent_name(np, i);
>  
> -	regmap = syscon_node_to_regmap(np);
> +	regmap = device_node_to_regmap(np);
>  	if (IS_ERR(regmap))
>  		return;
>  
> diff --git a/drivers/clk/at91/sam9x60.c b/drivers/clk/at91/sam9x60.c
> index 3e20aa68259f..2b4c67485eee 100644
> --- a/drivers/clk/at91/sam9x60.c
> +++ b/drivers/clk/at91/sam9x60.c
> @@ -178,7 +178,7 @@ static void __init sam9x60_pmc_setup(struct device_node *np)
>  		return;
>  	mainxtal_name = of_clk_get_parent_name(np, i);
>  
> -	regmap = syscon_node_to_regmap(np);
> +	regmap = device_node_to_regmap(np);
>  	if (IS_ERR(regmap))
>  		return;
>  
> diff --git a/drivers/clk/at91/sama5d3.c b/drivers/clk/at91/sama5d3.c
> index 5e4e44dd4c37..5609b04e6565 100644
> --- a/drivers/clk/at91/sama5d3.c
> +++ b/drivers/clk/at91/sama5d3.c
> @@ -121,7 +121,7 @@ static void __init sama5d3_pmc_setup(struct device_node *np)
>  		return;
>  	mainxtal_name = of_clk_get_parent_name(np, i);
>  
> -	regmap = syscon_node_to_regmap(np);
> +	regmap = device_node_to_regmap(np);
>  	if (IS_ERR(regmap))
>  		return;
>  
> -- 
> 2.27.0
> 

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH] clk: at91: fix possible dead lock in new drivers

[Stephen Boyd]

Quoting Ahmad Fatoum (2020-07-03 00:32:35)
> syscon_node_to_regmap() will make the created regmap get and enable the
> first clock it can parse from the device tree. This clock is not needed to
> access the registers and should not be enabled at that time.
> 
> Use device_node_to_regmap to resolve this as it looks up the regmap in
> the same list but doesn't care about the clocks. This issue is detected
> by lockdep when booting the sama5d3 with a device tree containing the
> new clk bindings.
> 
> This fix already happened in 6956eb33abb5 ("clk: at91: fix possible
> deadlock") for the drivers that had been migrated to the new clk binding
> back then. This does the same for the new drivers as well.
> 
> Fixes: 01e2113de9a5 ("clk: at91: add sam9x60 pmc driver")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---

Applied to clk-next