[PATCH] clk: qcom: gdsc: Add a flag to skip setting power collapse bits

[PATCH] clk: qcom: gdsc: Add a flag to skip setting power collapse bits

[Georgi Djakov]

The sdm845 platforms have a hardware issue that requires keeping
some of the MMNOC GDSCs in SW collapse mode (which is the power-on
default). But if some driver tries to use these GDSCs and the mode
is updated because of runtime pm calls, we may get a board hang.
Introduce a flag to skip any updates to the power collapse settings
for the impacted GDSCs to avoid unexpected board hangs.

Cc: Mike Tipton <quic_mdtipton@quicinc.com>
Cc: Vivek Aknurwar <quic_viveka@quicinc.com>
Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
---
 drivers/clk/qcom/gcc-sdm845.c | 6 +++---
 drivers/clk/qcom/gdsc.c       | 3 +++
 drivers/clk/qcom/gdsc.h       | 1 +
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/qcom/gcc-sdm845.c b/drivers/clk/qcom/gcc-sdm845.c
index dc3aa7014c3e..019b780e31c8 100644
--- a/drivers/clk/qcom/gcc-sdm845.c
+++ b/drivers/clk/qcom/gcc-sdm845.c
@@ -3503,7 +3503,7 @@ static struct gdsc hlos1_vote_mmnoc_mmu_tbu_hf0_gdsc = {
 		.name = "hlos1_vote_mmnoc_mmu_tbu_hf0_gdsc",
 	},
 	.pwrsts = PWRSTS_OFF_ON,
-	.flags = VOTABLE,
+	.flags = VOTABLE | SKIP_SET_COLLAPSE,
 };
 
 static struct gdsc hlos1_vote_mmnoc_mmu_tbu_hf1_gdsc = {
@@ -3512,7 +3512,7 @@ static struct gdsc hlos1_vote_mmnoc_mmu_tbu_hf1_gdsc = {
 		.name = "hlos1_vote_mmnoc_mmu_tbu_hf1_gdsc",
 	},
 	.pwrsts = PWRSTS_OFF_ON,
-	.flags = VOTABLE,
+	.flags = VOTABLE | SKIP_SET_COLLAPSE,
 };
 
 static struct gdsc hlos1_vote_mmnoc_mmu_tbu_sf_gdsc = {
@@ -3521,7 +3521,7 @@ static struct gdsc hlos1_vote_mmnoc_mmu_tbu_sf_gdsc = {
 		.name = "hlos1_vote_mmnoc_mmu_tbu_sf_gdsc",
 	},
 	.pwrsts = PWRSTS_OFF_ON,
-	.flags = VOTABLE,
+	.flags = VOTABLE | SKIP_SET_COLLAPSE,
 };
 
 static struct clk_regmap *gcc_sdm670_clocks[] = {
diff --git a/drivers/clk/qcom/gdsc.c b/drivers/clk/qcom/gdsc.c
index fa5fe4c2a2ee..4b83cec9137c 100644
--- a/drivers/clk/qcom/gdsc.c
+++ b/drivers/clk/qcom/gdsc.c
@@ -121,6 +121,9 @@ static int gdsc_update_collapse_bit(struct gdsc *sc, bool val)
 	u32 reg, mask;
 	int ret;
 
+	if (sc->flags & SKIP_SET_COLLAPSE)
+		return 0;
+
 	if (sc->collapse_mask) {
 		reg = sc->collapse_ctrl;
 		mask = sc->collapse_mask;
diff --git a/drivers/clk/qcom/gdsc.h b/drivers/clk/qcom/gdsc.h
index 1e2779b823d1..6bb7e023a19a 100644
--- a/drivers/clk/qcom/gdsc.h
+++ b/drivers/clk/qcom/gdsc.h
@@ -68,6 +68,7 @@ struct gdsc {
 #define RETAIN_FF_ENABLE	BIT(7)
 #define NO_RET_PERIPH	BIT(8)
 #define HW_CTRL_TRIGGER	BIT(9)
+#define SKIP_SET_COLLAPSE	BIT(10)
 	struct reset_controller_dev	*rcdev;
 	unsigned int			*resets;
 	unsigned int			reset_count;

Re: [PATCH] clk: qcom: gdsc: Add a flag to skip setting power collapse bits

[Stephen Boyd]

Quoting Georgi Djakov (2024-08-13 05:00:15)
> The sdm845 platforms have a hardware issue that requires keeping
> some of the MMNOC GDSCs in SW collapse mode (which is the power-on
> default). But if some driver tries to use these GDSCs and the mode
> is updated because of runtime pm calls, we may get a board hang.
> Introduce a flag to skip any updates to the power collapse settings
> for the impacted GDSCs to avoid unexpected board hangs.

Can you add a Fixes tag? And does this need to go to stable kernels?

Re: [PATCH] clk: qcom: gdsc: Add a flag to skip setting power collapse bits

[Georgi Djakov]

On 8/17/2024 12:48 AM, Stephen Boyd wrote:
> Quoting Georgi Djakov (2024-08-13 05:00:15)
>> The sdm845 platforms have a hardware issue that requires keeping
>> some of the MMNOC GDSCs in SW collapse mode (which is the power-on
>> default). But if some driver tries to use these GDSCs and the mode
>> is updated because of runtime pm calls, we may get a board hang.
>> Introduce a flag to skip any updates to the power collapse settings
>> for the impacted GDSCs to avoid unexpected board hangs.
> 
> Can you add a Fixes tag? And does this need to go to stable kernels?

These GDSCs got a user in v6.11-rc1 and there is currently a workaround
in place to avoid the hang, but this patch is the proper way to handle
it. Getting it into either fixes or next is both fine. There is no need
to backport it, as these GDSCs are not used on older kernels.

Thanks,
Georgi

Re: [PATCH] clk: qcom: gdsc: Add a flag to skip setting power collapse bits

[Mike Tipton]

On Tue, Aug 13, 2024 at 05:00:15AM -0700, Georgi Djakov wrote:
> The sdm845 platforms have a hardware issue that requires keeping
> some of the MMNOC GDSCs in SW collapse mode (which is the power-on
> default). But if some driver tries to use these GDSCs and the mode
> is updated because of runtime pm calls, we may get a board hang.
> Introduce a flag to skip any updates to the power collapse settings
> for the impacted GDSCs to avoid unexpected board hangs.
> 
> Cc: Mike Tipton <quic_mdtipton@quicinc.com>
> Cc: Vivek Aknurwar <quic_viveka@quicinc.com>
> Signed-off-by: Georgi Djakov <quic_c_gdjako@quicinc.com>
> ---
>  drivers/clk/qcom/gcc-sdm845.c | 6 +++---
>  drivers/clk/qcom/gdsc.c       | 3 +++
>  drivers/clk/qcom/gdsc.h       | 1 +
>  3 files changed, 7 insertions(+), 3 deletions(-)
> 

Reviewed-by: Mike Tipton <quic_mdtipton@quicinc.com>