| Message ID | 1404302638-3003-2-git-send-email-rogerq@ti.com |
|---|---|
| State | Superseded |
| Headers | show |
On 07/02/2014 07:03 AM, Roger Quadros wrote: > After clarification from the hardware team it was found that > this 1.8V PHY supply can't be switched OFF when SoC is Active. > It can only be switched off when in PORz (power on reset). I dont think folks know the reasoning why hardware team decided that the voltage rail cannot be switched off -> I suggest adding the following information as well. Since isolation is not present in the design for these PHY IPs to allow for the PHY rail to be switched off, there is a very high risk of IP reliability and additional leakage paths which can result in additional power consumption. Only scenario where this rail can be switched off is part of Power on reset sequencing, but it needs to be kept always-on during operation. > > This patch is required for proper functionality of USB, SATA > and PCIe on DRA7-evm. > > CC: Rajendra Nayak <rnayak@ti.com> > CC: Tero Kristo <t-kristo@ti.com> > Signed-off-by: Roger Quadros <rogerq@ti.com> > --- > arch/arm/boot/dts/dra7-evm.dts | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/arm/boot/dts/dra7-evm.dts b/arch/arm/boot/dts/dra7-evm.dts > index 4adc280..8308954 100644 > --- a/arch/arm/boot/dts/dra7-evm.dts > +++ b/arch/arm/boot/dts/dra7-evm.dts > @@ -240,6 +240,7 @@ > regulator-name = "ldo3"; > regulator-min-microvolt = <1800000>; > regulator-max-microvolt = <1800000>; > + regulator-always-on; > regulator-boot-on; > }; > >
On 07/02/2014 04:05 PM, Nishanth Menon wrote: > On 07/02/2014 07:03 AM, Roger Quadros wrote: >> After clarification from the hardware team it was found that >> this 1.8V PHY supply can't be switched OFF when SoC is Active. >> It can only be switched off when in PORz (power on reset). > > I dont think folks know the reasoning why hardware team decided that > the voltage rail cannot be switched off -> I suggest adding the > following information as well. > > Since isolation is not present in the design for these PHY IPs to > allow for the PHY rail to be switched off, there is a very high risk > of IP reliability and additional leakage paths which can result in > additional power consumption. > > Only scenario where this rail can be switched off is part of Power on > reset sequencing, but it needs to be kept always-on during operation. This sort of information should be in the TRM instead, but doesn't harm to be in the commit message so I'll do that. Thanks. cheers, -roger > >> >> This patch is required for proper functionality of USB, SATA >> and PCIe on DRA7-evm. >> >> CC: Rajendra Nayak <rnayak@ti.com> >> CC: Tero Kristo <t-kristo@ti.com> >> Signed-off-by: Roger Quadros <rogerq@ti.com> >> --- >> arch/arm/boot/dts/dra7-evm.dts | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/arch/arm/boot/dts/dra7-evm.dts b/arch/arm/boot/dts/dra7-evm.dts >> index 4adc280..8308954 100644 >> --- a/arch/arm/boot/dts/dra7-evm.dts >> +++ b/arch/arm/boot/dts/dra7-evm.dts >> @@ -240,6 +240,7 @@ >> regulator-name = "ldo3"; >> regulator-min-microvolt = <1800000>; >> regulator-max-microvolt = <1800000>; >> + regulator-always-on; >> regulator-boot-on; >> }; >> >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
diff --git a/arch/arm/boot/dts/dra7-evm.dts b/arch/arm/boot/dts/dra7-evm.dts index 4adc280..8308954 100644 --- a/arch/arm/boot/dts/dra7-evm.dts +++ b/arch/arm/boot/dts/dra7-evm.dts @@ -240,6 +240,7 @@ regulator-name = "ldo3"; regulator-min-microvolt = <1800000>; regulator-max-microvolt = <1800000>; + regulator-always-on; regulator-boot-on; };
After clarification from the hardware team it was found that this 1.8V PHY supply can't be switched OFF when SoC is Active. It can only be switched off when in PORz (power on reset). This patch is required for proper functionality of USB, SATA and PCIe on DRA7-evm. CC: Rajendra Nayak <rnayak@ti.com> CC: Tero Kristo <t-kristo@ti.com> Signed-off-by: Roger Quadros <rogerq@ti.com> --- arch/arm/boot/dts/dra7-evm.dts | 1 + 1 file changed, 1 insertion(+)