[PATCH v5 0/2] Fix missing TCU clock for X1000/X1830 SoCs

[PATCH v5 0/2] Fix missing TCU clock for X1000/X1830 SoCs

[Aidan MacDonald]

v5: fix use of uninitialized variable reported by kernel test robot & Dan Carpenter
v4: resend of v3 with some minor changes
v3: https://lore.kernel.org/linux-mips/20220224150326.525707-1-aidanmacdonald.0x0@gmail.com/

Aidan MacDonald (2):
  mips: dts: ingenic: Add TCU clock to x1000/x1830 tcu device node
  clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

 arch/mips/boot/dts/ingenic/x1000.dtsi |  5 ++--
 arch/mips/boot/dts/ingenic/x1830.dtsi |  5 ++--
 drivers/clk/ingenic/tcu.c             | 35 +++++++++++++++++++--------
 3 files changed, 31 insertions(+), 14 deletions(-)

-- 
2.35.1

[PATCH v5 1/2] mips: dts: ingenic: Add TCU clock to x1000/x1830 tcu device node

[Aidan MacDonald]

This clock is a gate for the TCU hardware block on these SoCs, but
it wasn't included in the device tree since the ingenic-tcu driver
erroneously did not request it.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 arch/mips/boot/dts/ingenic/x1000.dtsi | 5 +++--
 arch/mips/boot/dts/ingenic/x1830.dtsi | 5 +++--
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/mips/boot/dts/ingenic/x1000.dtsi b/arch/mips/boot/dts/ingenic/x1000.dtsi
index 8bd27edef216..c69df8eb158e 100644
--- a/arch/mips/boot/dts/ingenic/x1000.dtsi
+++ b/arch/mips/boot/dts/ingenic/x1000.dtsi
@@ -111,8 +111,9 @@ tcu: timer@10002000 {
 
 		clocks = <&cgu X1000_CLK_RTCLK>,
 			 <&cgu X1000_CLK_EXCLK>,
-			 <&cgu X1000_CLK_PCLK>;
-		clock-names = "rtc", "ext", "pclk";
+			 <&cgu X1000_CLK_PCLK>,
+			 <&cgu X1000_CLK_TCU>;
+		clock-names = "rtc", "ext", "pclk", "tcu";
 
 		interrupt-controller;
 		#interrupt-cells = <1>;
diff --git a/arch/mips/boot/dts/ingenic/x1830.dtsi b/arch/mips/boot/dts/ingenic/x1830.dtsi
index 2595df8671c7..4408df24ca98 100644
--- a/arch/mips/boot/dts/ingenic/x1830.dtsi
+++ b/arch/mips/boot/dts/ingenic/x1830.dtsi
@@ -104,8 +104,9 @@ tcu: timer@10002000 {
 
 		clocks = <&cgu X1830_CLK_RTCLK>,
 			 <&cgu X1830_CLK_EXCLK>,
-			 <&cgu X1830_CLK_PCLK>;
-		clock-names = "rtc", "ext", "pclk";
+			 <&cgu X1830_CLK_PCLK>,
+			 <&cgu X1830_CLK_TCU>;
+		clock-names = "rtc", "ext", "pclk", "tcu";
 
 		interrupt-controller;
 		#interrupt-cells = <1>;
-- 
2.35.1

[PATCH v5 2/2] clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

[Aidan MacDonald]

The TCU clock gate on X1000 wasn't requested by the driver and could
be gated automatically later on in boot, which prevents timers from
running and breaks PWM.

Add a workaround to support old device trees that don't specify the
"tcu" clock gate. In this case the kernel will print a warning and
attempt to continue without the clock, which is wrong, but it could
work if "clk_ignore_unused" is in the kernel arguments.

Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
---
 drivers/clk/ingenic/tcu.c | 35 +++++++++++++++++++++++++----------
 1 file changed, 25 insertions(+), 10 deletions(-)

diff --git a/drivers/clk/ingenic/tcu.c b/drivers/clk/ingenic/tcu.c
index 77acfbeb4830..201bf6e6b6e0 100644
--- a/drivers/clk/ingenic/tcu.c
+++ b/drivers/clk/ingenic/tcu.c
@@ -31,6 +31,7 @@ struct ingenic_soc_info {
 	unsigned int num_channels;
 	bool has_ost;
 	bool has_tcu_clk;
+	bool allow_missing_tcu_clk;
 };
 
 struct ingenic_tcu_clk_info {
@@ -320,7 +321,8 @@ static const struct ingenic_soc_info jz4770_soc_info = {
 static const struct ingenic_soc_info x1000_soc_info = {
 	.num_channels = 8,
 	.has_ost = false, /* X1000 has OST, but it not belong TCU */
-	.has_tcu_clk = false,
+	.has_tcu_clk = true,
+	.allow_missing_tcu_clk = true,
 };
 
 static const struct of_device_id __maybe_unused ingenic_tcu_of_match[] __initconst = {
@@ -355,14 +357,27 @@ static int __init ingenic_tcu_probe(struct device_node *np)
 		tcu->clk = of_clk_get_by_name(np, "tcu");
 		if (IS_ERR(tcu->clk)) {
 			ret = PTR_ERR(tcu->clk);
-			pr_crit("Cannot get TCU clock\n");
-			goto err_free_tcu;
-		}
 
-		ret = clk_prepare_enable(tcu->clk);
-		if (ret) {
-			pr_crit("Unable to enable TCU clock\n");
-			goto err_put_clk;
+			/*
+			 * Old device trees for some SoCs did not include the
+			 * TCU clock because this driver (incorrectly) didn't
+			 * use it. In this case we complain loudly and attempt
+			 * to continue without the clock, which might work if
+			 * booting with workarounds like "clk_ignore_unused".
+			 */
+			if (tcu->soc_info->allow_missing_tcu_clk && ret == -EINVAL) {
+				pr_warn("TCU clock missing from device tree, please update your device tree\n");
+				tcu->clk = NULL;
+			} else {
+				pr_crit("Cannot get TCU clock from device tree\n");
+				goto err_free_tcu;
+			}
+		} else {
+			ret = clk_prepare_enable(tcu->clk);
+			if (ret) {
+				pr_crit("Unable to enable TCU clock\n");
+				goto err_put_clk;
+			}
 		}
 	}
 
@@ -432,10 +447,10 @@ static int __init ingenic_tcu_probe(struct device_node *np)
 			clk_hw_unregister(tcu->clocks->hws[i]);
 	kfree(tcu->clocks);
 err_clk_disable:
-	if (tcu->soc_info->has_tcu_clk)
+	if (tcu->clk)
 		clk_disable_unprepare(tcu->clk);
 err_put_clk:
-	if (tcu->soc_info->has_tcu_clk)
+	if (tcu->clk)
 		clk_put(tcu->clk);
 err_free_tcu:
 	kfree(tcu);
-- 
2.35.1

Re: [PATCH v5 1/2] mips: dts: ingenic: Add TCU clock to x1000/x1830 tcu device node

[Paul Cercueil]

Hi,

Le mar., avril 12 2022 at 13:27:49 +0100, Aidan MacDonald 
<aidanmacdonald.0x0@gmail.com> a écrit :
> This clock is a gate for the TCU hardware block on these SoCs, but
> it wasn't included in the device tree since the ingenic-tcu driver
> erroneously did not request it.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>

Reviewed-by: Paul Cercueil <paul@crapouillou.net>

Cheers,
-Paul

> ---
>  arch/mips/boot/dts/ingenic/x1000.dtsi | 5 +++--
>  arch/mips/boot/dts/ingenic/x1830.dtsi | 5 +++--
>  2 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/mips/boot/dts/ingenic/x1000.dtsi 
> b/arch/mips/boot/dts/ingenic/x1000.dtsi
> index 8bd27edef216..c69df8eb158e 100644
> --- a/arch/mips/boot/dts/ingenic/x1000.dtsi
> +++ b/arch/mips/boot/dts/ingenic/x1000.dtsi
> @@ -111,8 +111,9 @@ tcu: timer@10002000 {
> 
>  		clocks = <&cgu X1000_CLK_RTCLK>,
>  			 <&cgu X1000_CLK_EXCLK>,
> -			 <&cgu X1000_CLK_PCLK>;
> -		clock-names = "rtc", "ext", "pclk";
> +			 <&cgu X1000_CLK_PCLK>,
> +			 <&cgu X1000_CLK_TCU>;
> +		clock-names = "rtc", "ext", "pclk", "tcu";
> 
>  		interrupt-controller;
>  		#interrupt-cells = <1>;
> diff --git a/arch/mips/boot/dts/ingenic/x1830.dtsi 
> b/arch/mips/boot/dts/ingenic/x1830.dtsi
> index 2595df8671c7..4408df24ca98 100644
> --- a/arch/mips/boot/dts/ingenic/x1830.dtsi
> +++ b/arch/mips/boot/dts/ingenic/x1830.dtsi
> @@ -104,8 +104,9 @@ tcu: timer@10002000 {
> 
>  		clocks = <&cgu X1830_CLK_RTCLK>,
>  			 <&cgu X1830_CLK_EXCLK>,
> -			 <&cgu X1830_CLK_PCLK>;
> -		clock-names = "rtc", "ext", "pclk";
> +			 <&cgu X1830_CLK_PCLK>,
> +			 <&cgu X1830_CLK_TCU>;
> +		clock-names = "rtc", "ext", "pclk", "tcu";
> 
>  		interrupt-controller;
>  		#interrupt-cells = <1>;
> --
> 2.35.1
> 

Re: [PATCH v5 2/2] clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

[Paul Cercueil]

Hi,

Le mar., avril 12 2022 at 13:27:50 +0100, Aidan MacDonald 
<aidanmacdonald.0x0@gmail.com> a écrit :
> The TCU clock gate on X1000 wasn't requested by the driver and could
> be gated automatically later on in boot, which prevents timers from
> running and breaks PWM.
> 
> Add a workaround to support old device trees that don't specify the
> "tcu" clock gate. In this case the kernel will print a warning and
> attempt to continue without the clock, which is wrong, but it could
> work if "clk_ignore_unused" is in the kernel arguments.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>

Reviewed-by: Paul Cercueil <paul@crapouillou.net>

Cheers,
-Paul

> ---
>  drivers/clk/ingenic/tcu.c | 35 +++++++++++++++++++++++++----------
>  1 file changed, 25 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/clk/ingenic/tcu.c b/drivers/clk/ingenic/tcu.c
> index 77acfbeb4830..201bf6e6b6e0 100644
> --- a/drivers/clk/ingenic/tcu.c
> +++ b/drivers/clk/ingenic/tcu.c
> @@ -31,6 +31,7 @@ struct ingenic_soc_info {
>  	unsigned int num_channels;
>  	bool has_ost;
>  	bool has_tcu_clk;
> +	bool allow_missing_tcu_clk;
>  };
> 
>  struct ingenic_tcu_clk_info {
> @@ -320,7 +321,8 @@ static const struct ingenic_soc_info 
> jz4770_soc_info = {
>  static const struct ingenic_soc_info x1000_soc_info = {
>  	.num_channels = 8,
>  	.has_ost = false, /* X1000 has OST, but it not belong TCU */
> -	.has_tcu_clk = false,
> +	.has_tcu_clk = true,
> +	.allow_missing_tcu_clk = true,
>  };
> 
>  static const struct of_device_id __maybe_unused 
> ingenic_tcu_of_match[] __initconst = {
> @@ -355,14 +357,27 @@ static int __init ingenic_tcu_probe(struct 
> device_node *np)
>  		tcu->clk = of_clk_get_by_name(np, "tcu");
>  		if (IS_ERR(tcu->clk)) {
>  			ret = PTR_ERR(tcu->clk);
> -			pr_crit("Cannot get TCU clock\n");
> -			goto err_free_tcu;
> -		}
> 
> -		ret = clk_prepare_enable(tcu->clk);
> -		if (ret) {
> -			pr_crit("Unable to enable TCU clock\n");
> -			goto err_put_clk;
> +			/*
> +			 * Old device trees for some SoCs did not include the
> +			 * TCU clock because this driver (incorrectly) didn't
> +			 * use it. In this case we complain loudly and attempt
> +			 * to continue without the clock, which might work if
> +			 * booting with workarounds like "clk_ignore_unused".
> +			 */
> +			if (tcu->soc_info->allow_missing_tcu_clk && ret == -EINVAL) {
> +				pr_warn("TCU clock missing from device tree, please update your 
> device tree\n");
> +				tcu->clk = NULL;
> +			} else {
> +				pr_crit("Cannot get TCU clock from device tree\n");
> +				goto err_free_tcu;
> +			}
> +		} else {
> +			ret = clk_prepare_enable(tcu->clk);
> +			if (ret) {
> +				pr_crit("Unable to enable TCU clock\n");
> +				goto err_put_clk;
> +			}
>  		}
>  	}
> 
> @@ -432,10 +447,10 @@ static int __init ingenic_tcu_probe(struct 
> device_node *np)
>  			clk_hw_unregister(tcu->clocks->hws[i]);
>  	kfree(tcu->clocks);
>  err_clk_disable:
> -	if (tcu->soc_info->has_tcu_clk)
> +	if (tcu->clk)
>  		clk_disable_unprepare(tcu->clk);
>  err_put_clk:
> -	if (tcu->soc_info->has_tcu_clk)
> +	if (tcu->clk)
>  		clk_put(tcu->clk);
>  err_free_tcu:
>  	kfree(tcu);
> --
> 2.35.1
> 

Re: [PATCH v5 2/2] clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

[Stephen Boyd]

Quoting Aidan MacDonald (2022-04-12 05:27:50)
> The TCU clock gate on X1000 wasn't requested by the driver and could
> be gated automatically later on in boot, which prevents timers from
> running and breaks PWM.
> 
> Add a workaround to support old device trees that don't specify the
> "tcu" clock gate. In this case the kernel will print a warning and
> attempt to continue without the clock, which is wrong, but it could
> work if "clk_ignore_unused" is in the kernel arguments.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> ---

Can I take just this one patch through clk tree without the dts part?
dts snippets go through soc trees.

Re: [PATCH v5 2/2] clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

[Aidan MacDonald]

On Wed, May 18, 2022 at 01:47:32PM -0700, Stephen Boyd wrote:
> Quoting Aidan MacDonald (2022-04-12 05:27:50)
> > The TCU clock gate on X1000 wasn't requested by the driver and could
> > be gated automatically later on in boot, which prevents timers from
> > running and breaks PWM.
> > 
> > Add a workaround to support old device trees that don't specify the
> > "tcu" clock gate. In this case the kernel will print a warning and
> > attempt to continue without the clock, which is wrong, but it could
> > work if "clk_ignore_unused" is in the kernel arguments.
> > 
> > Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> > ---
> 
> Can I take just this one patch through clk tree without the dts part?
> dts snippets go through soc trees.

Yeah. The patches can go through in any order but they both need to be
merged to fix the bug -- each on its own should not change any behavior.

Regards,
Aidan

Re: [PATCH v5 2/2] clk: ingenic-tcu: Fix missing TCU clock for X1000 SoCs

[Stephen Boyd]

Quoting Aidan MacDonald (2022-04-12 05:27:50)
> The TCU clock gate on X1000 wasn't requested by the driver and could
> be gated automatically later on in boot, which prevents timers from
> running and breaks PWM.
> 
> Add a workaround to support old device trees that don't specify the
> "tcu" clock gate. In this case the kernel will print a warning and
> attempt to continue without the clock, which is wrong, but it could
> work if "clk_ignore_unused" is in the kernel arguments.
> 
> Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
> ---

Applied to clk-next