[PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[Alex Elder]

The pll1_d8 clock is enabled by the boot loader, and is ultimately a
parent for numerous clocks, including those used by APB and AXI buses.
Guodong Xu discovered that this clock got disabled while responding to
getting -EPROBE_DEFER when requesting a reset controller.

The needed clock (CLK_DMA, along with its parents) had already been
enabled.  To respond to the probe deferral return, the CLK_DMA clock
was disabled, and this led to parent clocks also reducing their enable
count.  When the enable count for pll1_d8 was decremented it became 0,
which caused it to be disabled.  This led to a system hang.

Marking that clock critical resolves this by preventing it from being
disabled.

Define a new macro CCU_FACTOR_GATE_DEFINE() to allow clock flags to
be supplied for a CCU_FACTOR_GATE clock.

Fixes: 1b72c59db0add ("clk: spacemit: Add clock support for SpacemiT K1 SoC")
Signed-off-by: Alex Elder <elder@riscstar.com>
Tested-by: Guodong Xu <guodong@riscstar.com>
Reviewed-by: Haylen Chu <heylenay@4d2.org>
---
v3: Define struct with static scope; added Haylen's Reviewed-by
v2: Reworded the description to provide better detail

 drivers/clk/spacemit/ccu-k1.c  |  3 ++-
 drivers/clk/spacemit/ccu_mix.h | 21 +++++++++++++--------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
index cdde37a052353..df65009a07bb1 100644
--- a/drivers/clk/spacemit/ccu-k1.c
+++ b/drivers/clk/spacemit/ccu-k1.c
@@ -170,7 +170,8 @@ CCU_FACTOR_GATE_DEFINE(pll1_d4, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(3), 4,
 CCU_FACTOR_GATE_DEFINE(pll1_d5, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(4), 5, 1);
 CCU_FACTOR_GATE_DEFINE(pll1_d6, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(5), 6, 1);
 CCU_FACTOR_GATE_DEFINE(pll1_d7, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(6), 7, 1);
-CCU_FACTOR_GATE_DEFINE(pll1_d8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(7), 8, 1);
+CCU_FACTOR_GATE_FLAGS_DEFINE(pll1_d8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(7), 8, 1,
+		CLK_IS_CRITICAL);
 CCU_FACTOR_GATE_DEFINE(pll1_d11_223p4, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(15), 11, 1);
 CCU_FACTOR_GATE_DEFINE(pll1_d13_189, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(16), 13, 1);
 CCU_FACTOR_GATE_DEFINE(pll1_d23_106p8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(20), 23, 1);
diff --git a/drivers/clk/spacemit/ccu_mix.h b/drivers/clk/spacemit/ccu_mix.h
index 51d19f5d6aacb..54d40cd39b275 100644
--- a/drivers/clk/spacemit/ccu_mix.h
+++ b/drivers/clk/spacemit/ccu_mix.h
@@ -101,16 +101,21 @@ static struct ccu_mix _name = {							\
 	}									\
 }
 
+#define CCU_FACTOR_GATE_FLAGS_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
+			       _mul, _flags)					\
+static struct ccu_mix _name = {							\
+	.gate	= CCU_GATE_INIT(_mask_gate),					\
+	.factor	= CCU_FACTOR_INIT(_div, _mul),					\
+	.common = {								\
+		.reg_ctrl	= _reg_ctrl,					\
+		CCU_MIX_INITHW(_name, _parent, spacemit_ccu_factor_gate_ops, _flags)	\
+	}									\
+}
+
 #define CCU_FACTOR_GATE_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
 			       _mul)						\
-static struct ccu_mix _name = {							\
-	.gate	= CCU_GATE_INIT(_mask_gate),					\
-	.factor	= CCU_FACTOR_INIT(_div, _mul),					\
-	.common = {								\
-		.reg_ctrl	= _reg_ctrl,					\
-		CCU_MIX_INITHW(_name, _parent, spacemit_ccu_factor_gate_ops, 0)	\
-	}									\
-}
+	CCU_FACTOR_GATE_FLAGS_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
+			       _mul, 0)
 
 #define CCU_MUX_GATE_DEFINE(_name, _parents, _reg_ctrl, _shift, _width,		\
 			    _mask_gate, _flags)					\

base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494
-- 
2.45.2

Re: [PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[Alex Elder]

On 6/12/25 5:48 PM, Alex Elder wrote:
> The pll1_d8 clock is enabled by the boot loader, and is ultimately a
> parent for numerous clocks, including those used by APB and AXI buses.
> Guodong Xu discovered that this clock got disabled while responding to
> getting -EPROBE_DEFER when requesting a reset controller.
> 
> The needed clock (CLK_DMA, along with its parents) had already been
> enabled.  To respond to the probe deferral return, the CLK_DMA clock
> was disabled, and this led to parent clocks also reducing their enable
> count.  When the enable count for pll1_d8 was decremented it became 0,
> which caused it to be disabled.  This led to a system hang.
> 
> Marking that clock critical resolves this by preventing it from being
> disabled.
> 
> Define a new macro CCU_FACTOR_GATE_DEFINE() to allow clock flags to
> be supplied for a CCU_FACTOR_GATE clock.

Is there any reason this bug fix cannot be merged?  It was
first posted a month ago, and although there was some initial
discussion that led to revisions, this version has been waiting
for over three weeks.

					-Alex

> 
> Fixes: 1b72c59db0add ("clk: spacemit: Add clock support for SpacemiT K1 SoC")
> Signed-off-by: Alex Elder <elder@riscstar.com>
> Tested-by: Guodong Xu <guodong@riscstar.com>
> Reviewed-by: Haylen Chu <heylenay@4d2.org>
> ---
> v3: Define struct with static scope; added Haylen's Reviewed-by
> v2: Reworded the description to provide better detail
> 
>   drivers/clk/spacemit/ccu-k1.c  |  3 ++-
>   drivers/clk/spacemit/ccu_mix.h | 21 +++++++++++++--------
>   2 files changed, 15 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
> index cdde37a052353..df65009a07bb1 100644
> --- a/drivers/clk/spacemit/ccu-k1.c
> +++ b/drivers/clk/spacemit/ccu-k1.c
> @@ -170,7 +170,8 @@ CCU_FACTOR_GATE_DEFINE(pll1_d4, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(3), 4,
>   CCU_FACTOR_GATE_DEFINE(pll1_d5, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(4), 5, 1);
>   CCU_FACTOR_GATE_DEFINE(pll1_d6, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(5), 6, 1);
>   CCU_FACTOR_GATE_DEFINE(pll1_d7, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(6), 7, 1);
> -CCU_FACTOR_GATE_DEFINE(pll1_d8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(7), 8, 1);
> +CCU_FACTOR_GATE_FLAGS_DEFINE(pll1_d8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(7), 8, 1,
> +		CLK_IS_CRITICAL);
>   CCU_FACTOR_GATE_DEFINE(pll1_d11_223p4, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(15), 11, 1);
>   CCU_FACTOR_GATE_DEFINE(pll1_d13_189, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(16), 13, 1);
>   CCU_FACTOR_GATE_DEFINE(pll1_d23_106p8, CCU_PARENT_HW(pll1), APBS_PLL1_SWCR2, BIT(20), 23, 1);
> diff --git a/drivers/clk/spacemit/ccu_mix.h b/drivers/clk/spacemit/ccu_mix.h
> index 51d19f5d6aacb..54d40cd39b275 100644
> --- a/drivers/clk/spacemit/ccu_mix.h
> +++ b/drivers/clk/spacemit/ccu_mix.h
> @@ -101,16 +101,21 @@ static struct ccu_mix _name = {							\
>   	}									\
>   }
>   
> +#define CCU_FACTOR_GATE_FLAGS_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
> +			       _mul, _flags)					\
> +static struct ccu_mix _name = {							\
> +	.gate	= CCU_GATE_INIT(_mask_gate),					\
> +	.factor	= CCU_FACTOR_INIT(_div, _mul),					\
> +	.common = {								\
> +		.reg_ctrl	= _reg_ctrl,					\
> +		CCU_MIX_INITHW(_name, _parent, spacemit_ccu_factor_gate_ops, _flags)	\
> +	}									\
> +}
> +
>   #define CCU_FACTOR_GATE_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
>   			       _mul)						\
> -static struct ccu_mix _name = {							\
> -	.gate	= CCU_GATE_INIT(_mask_gate),					\
> -	.factor	= CCU_FACTOR_INIT(_div, _mul),					\
> -	.common = {								\
> -		.reg_ctrl	= _reg_ctrl,					\
> -		CCU_MIX_INITHW(_name, _parent, spacemit_ccu_factor_gate_ops, 0)	\
> -	}									\
> -}
> +	CCU_FACTOR_GATE_FLAGS_DEFINE(_name, _parent, _reg_ctrl, _mask_gate, _div,	\
> +			       _mul, 0)
>   
>   #define CCU_MUX_GATE_DEFINE(_name, _parents, _reg_ctrl, _shift, _width,		\
>   			    _mask_gate, _flags)					\
> 
> base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494

Re: [PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[Yixun Lan]

Hi Alex,

On 07:19 Mon 07 Jul     , Alex Elder wrote:
> On 6/12/25 5:48 PM, Alex Elder wrote:
> > The pll1_d8 clock is enabled by the boot loader, and is ultimately a
> > parent for numerous clocks, including those used by APB and AXI buses.
> > Guodong Xu discovered that this clock got disabled while responding to
> > getting -EPROBE_DEFER when requesting a reset controller.
> > 
> > The needed clock (CLK_DMA, along with its parents) had already been
> > enabled.  To respond to the probe deferral return, the CLK_DMA clock
> > was disabled, and this led to parent clocks also reducing their enable
> > count.  When the enable count for pll1_d8 was decremented it became 0,
> > which caused it to be disabled.  This led to a system hang.
> > 
> > Marking that clock critical resolves this by preventing it from being
> > disabled.
> > 
> > Define a new macro CCU_FACTOR_GATE_DEFINE() to allow clock flags to
> > be supplied for a CCU_FACTOR_GATE clock.
> 
> Is there any reason this bug fix cannot be merged?  It was
> first posted a month ago, and although there was some initial
> discussion that led to revisions, this version has been waiting
> for over three weeks.
> 
Ok, let me explain..

I've queued it at for-next but haven't sent out the "Applied" reply email,
it should be eventually merged for version v6.17 if things goes well.. 

the reason that I haven't pushed it hard for fixes branch is that only DMA 
is affected for now, but DMA isn't fully activated in current mainline
(No DT, No config merged), so I think it's fine if we target for-next..

-- 
Yixun Lan (dlan)

Re: [PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[Alex Elder]

On 7/7/25 9:28 AM, Yixun Lan wrote:
> Hi Alex,
> 
> On 07:19 Mon 07 Jul     , Alex Elder wrote:
>> On 6/12/25 5:48 PM, Alex Elder wrote:
>>> The pll1_d8 clock is enabled by the boot loader, and is ultimately a
>>> parent for numerous clocks, including those used by APB and AXI buses.
>>> Guodong Xu discovered that this clock got disabled while responding to
>>> getting -EPROBE_DEFER when requesting a reset controller.
>>>
>>> The needed clock (CLK_DMA, along with its parents) had already been
>>> enabled.  To respond to the probe deferral return, the CLK_DMA clock
>>> was disabled, and this led to parent clocks also reducing their enable
>>> count.  When the enable count for pll1_d8 was decremented it became 0,
>>> which caused it to be disabled.  This led to a system hang.
>>>
>>> Marking that clock critical resolves this by preventing it from being
>>> disabled.
>>>
>>> Define a new macro CCU_FACTOR_GATE_DEFINE() to allow clock flags to
>>> be supplied for a CCU_FACTOR_GATE clock.
>>
>> Is there any reason this bug fix cannot be merged?  It was
>> first posted a month ago, and although there was some initial
>> discussion that led to revisions, this version has been waiting
>> for over three weeks.
>>
> Ok, let me explain..
> 
> I've queued it at for-next but haven't sent out the "Applied" reply email,
> it should be eventually merged for version v6.17 if things goes well..
> 
> the reason that I haven't pushed it hard for fixes branch is that only DMA
> is affected for now, but DMA isn't fully activated in current mainline
> (No DT, No config merged), so I think it's fine if we target for-next..

OK, thanks for the explanation Yixun.  I've been working in the
networking subsystem for a long time and they tend to push bug
fixes out right away (once reviewed).  But you're right, this
particular bug fix does not affect any currently upstream code.

					-Alex

Re: [PATCH v3] clk: spacemit: mark K1 pll1_d8 as critical

[Yixun Lan]

On Thu, 12 Jun 2025 17:48:55 -0500, Alex Elder wrote:
> The pll1_d8 clock is enabled by the boot loader, and is ultimately a
> parent for numerous clocks, including those used by APB and AXI buses.
> Guodong Xu discovered that this clock got disabled while responding to
> getting -EPROBE_DEFER when requesting a reset controller.
> 
> The needed clock (CLK_DMA, along with its parents) had already been
> enabled.  To respond to the probe deferral return, the CLK_DMA clock
> was disabled, and this led to parent clocks also reducing their enable
> count.  When the enable count for pll1_d8 was decremented it became 0,
> which caused it to be disabled.  This led to a system hang.
> 
> [...]

Applied, thanks!

[1/1] clk: spacemit: mark K1 pll1_d8 as critical
      https://github.com/spacemit-com/linux/commit/7554729de27daf6d54bcf8689d863bbe267828bf

Best regards,
-- 
Yixun Lan