[PATCH v1 1/2] arm64: dts: exynos: Fix silent hang after boot

[PATCH v1 1/2] arm64: dts: exynos: Fix silent hang after boot

[Alim Akhtar]

Once regulators are disabled after kernel boot, on espresso
board silent hang observed because of LDO7 being disabled.
LDO7 actually provide power to CPU cores and non-cpu blocks
circuitries.
Keep this regulator always-on to fix this hang.

Fixes: 9589f7721e16 ("arm64: dts: Add S2MPS15 PMIC node on exynos7-espresso")
Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 - 
 arch/arm64/boot/dts/exynos/exynos7-espresso.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
index 790f12ca8981..bb86950032d3 100644
--- a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
+++ b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
@@ -157,6 +157,7 @@
 				regulator-min-microvolt = <700000>;
 				regulator-max-microvolt = <1150000>;
 				regulator-enable-ramp-delay = <125>;
+				regulator-always-on;
 			};
 
 			ldo8_reg: LDO8 {

base-commit: 9e50b94b3eb0d859a2586b5a40d7fd6e5afd9210
-- 
2.17.1

[PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on

[Alim Akhtar]

LDO12 on exynos7 supply power to VDDQ_UFS20_RESET,
in case this regulator is OFF, UFS host controller
can not send command to UFS device. To keep this supply
ON, set regulator-always-on property for this ldo.

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
---
 arch/arm64/boot/dts/exynos/exynos7-espresso.dts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
index bb86950032d3..92fecc539c6c 100644
--- a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
+++ b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
@@ -194,6 +194,7 @@
 				regulator-min-microvolt = <1000000>;
 				regulator-max-microvolt = <1300000>;
 				regulator-enable-ramp-delay = <125>;
+				regulator-always-on;
 			};
 
 			ldo13_reg: LDO13 {
-- 
2.17.1

Re: [PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on

[Krzysztof Kozlowski]

On Sun, Jul 05, 2020 at 12:39:18PM +0530, Alim Akhtar wrote:
> LDO12 on exynos7 supply power to VDDQ_UFS20_RESET,
> in case this regulator is OFF, UFS host controller
> can not send command to UFS device. To keep this supply
> ON, set regulator-always-on property for this ldo.

Why UFS does not take any supplies? This looks like a workaround for the
case of not implementing any consumer.

Best regards,
Krzysztof


> 
> Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
> ---
>  arch/arm64/boot/dts/exynos/exynos7-espresso.dts | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> index bb86950032d3..92fecc539c6c 100644
> --- a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> +++ b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> @@ -194,6 +194,7 @@
>  				regulator-min-microvolt = <1000000>;
>  				regulator-max-microvolt = <1300000>;
>  				regulator-enable-ramp-delay = <125>;
> +				regulator-always-on;
>  			};
>  
>  			ldo13_reg: LDO13 {
> -- 
> 2.17.1
> 

RE: [PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on

[Alim Akhtar]

Hi Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzk@kernel.org>
> Sent: 05 July 2020 23:53
> To: Alim Akhtar <alim.akhtar@samsung.com>
> Cc: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> samsung-soc@vger.kernel.org; linux-kernel@vger.kernel.org;
> robh+dt@kernel.org
> Subject: Re: [PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on
> 
> On Sun, Jul 05, 2020 at 12:39:18PM +0530, Alim Akhtar wrote:
> > LDO12 on exynos7 supply power to VDDQ_UFS20_RESET, in case this
> > regulator is OFF, UFS host controller can not send command to UFS
> > device. To keep this supply ON, set regulator-always-on property for
> > this ldo.
> 
> Why UFS does not take any supplies? This looks like a workaround for the case
> of not implementing any consumer.
> 
This particular supply is not part of UFS HCI spec and binding documentation, as per binding only one supply for host controller and three others for UFS device are needed. My best guess is, VDDQ_UFS20_RESET supply to reset logic block inside HCI, which might be specific to this controller version (I did not find any such supply in the latest host controller though).

> Best regards,
> Krzysztof
> 
> 
> >
> > Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
> > ---
> >  arch/arm64/boot/dts/exynos/exynos7-espresso.dts | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> > b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> > index bb86950032d3..92fecc539c6c 100644
> > --- a/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> > +++ b/arch/arm64/boot/dts/exynos/exynos7-espresso.dts
> > @@ -194,6 +194,7 @@
> >  				regulator-min-microvolt = <1000000>;
> >  				regulator-max-microvolt = <1300000>;
> >  				regulator-enable-ramp-delay = <125>;
> > +				regulator-always-on;
> >  			};
> >
> >  			ldo13_reg: LDO13 {
> > --
> > 2.17.1
> >

Re: [PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on

['Krzysztof Kozlowski']

On Mon, Jul 06, 2020 at 09:23:49PM +0530, Alim Akhtar wrote:
> Hi Krzysztof,
> 
> > -----Original Message-----
> > From: Krzysztof Kozlowski <krzk@kernel.org>
> > Sent: 05 July 2020 23:53
> > To: Alim Akhtar <alim.akhtar@samsung.com>
> > Cc: devicetree@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-
> > samsung-soc@vger.kernel.org; linux-kernel@vger.kernel.org;
> > robh+dt@kernel.org
> > Subject: Re: [PATCH v1 2/2] arm64: dts: exynos: keep LDO12 always-on
> > 
> > On Sun, Jul 05, 2020 at 12:39:18PM +0530, Alim Akhtar wrote:
> > > LDO12 on exynos7 supply power to VDDQ_UFS20_RESET, in case this
> > > regulator is OFF, UFS host controller can not send command to UFS
> > > device. To keep this supply ON, set regulator-always-on property for
> > > this ldo.
> > 
> > Why UFS does not take any supplies? This looks like a workaround for the case
> > of not implementing any consumer.
> > 
> This particular supply is not part of UFS HCI spec and binding documentation, as per binding only one supply for host controller and three others for UFS device are needed. My best guess is, VDDQ_UFS20_RESET supply to reset logic block inside HCI, which might be specific to this controller version (I did not find any such supply in the latest host controller though).

The bindings specific to Exynos7 UFS are then incomplete.  Anyway it's
nothing worth revisiting so I applied both patches.

Best regards,
Krzysztof