At late init all unused clocks are disabled. So clocks that were not
get before will be gated. In Keysone 2 SoC we have at least one
necessary clock that is not used by any driver - "msmcsram". This
clock is necessary, because it supplies the Multicore Shared Memory
Controller (MSMC). The MSMC provides memory protection for accesses to
the MSMC SRAM and DDR3 memory from system masters. It also manages
traffic among mastering peripherals and the EMIF.
This means that MSMC clock is always needed by SoC and cannot be gated.
It is only one from necessary clocks that was not used by any driver.
So to avoid its gating at late init we have to disable it in DT.
Signed-off-by: Ivan Khoronzhuk <[email protected]>
---
arch/arm/boot/dts/keystone-clocks.dtsi | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm/boot/dts/keystone-clocks.dtsi b/arch/arm/boot/dts/keystone-clocks.dtsi
index 2363593..e7aea2e 100644
--- a/arch/arm/boot/dts/keystone-clocks.dtsi
+++ b/arch/arm/boot/dts/keystone-clocks.dtsi
@@ -332,6 +332,7 @@ clocks {
compatible = "ti,keystone,psc-clock";
clocks = <&chipclk1>;
clock-output-names = "msmcsram";
+ status = "disabled";
reg = <0x02350038 0xb00>, <0x0235001c 0x400>;
reg-names = "control", "domain";
domain-id = <7>;
--
1.8.3.2
Ok. I will delete node for this clock from DT and send v1
On 01/30/2014 03:25 PM, Shilimkar, Santosh wrote:
> Disable is not good idea since it conveys wrong info....
>
> Hyperlink case was different.
>
> Sent from my Android phone using TouchDown (http://www.nitrodesk.com)
>
> -----Original Message-----
> *From:* Khoronzhuk, Ivan [[email protected]]
> *Received:* Thursday, 30 Jan 2014, 6:45am
> *To:* [email protected] [[email protected]]; [email protected]
> [[email protected]]
> *CC:* [email protected] [[email protected]]; [email protected]
> [[email protected]]; [email protected]
> [[email protected]]; [email protected]
> [[email protected]]; [email protected]
> [[email protected]]; [email protected]
> [[email protected]]; [email protected]
> [[email protected]]; Shilimkar, Santosh [[email protected]];
> Khoronzhuk, Ivan [[email protected]]
> *Subject:* [PATCH] ARM: keystone: dts: disable "msmcsram" clock
>
> At late init all unused clocks are disabled. So clocks that were not
> get before will be gated. In Keysone 2 SoC we have at least one
> necessary clock that is not used by any driver - "msmcsram". This
> clock is necessary, because it supplies the Multicore Shared Memory
> Controller (MSMC). The MSMC provides memory protection for accesses to
> the MSMC SRAM and DDR3 memory from system masters. It also manages
> traffic among mastering peripherals and the EMIF.
>
> This means that MSMC clock is always needed by SoC and cannot be gated.
> It is only one from necessary clocks that was not used by any driver.
> So to avoid its gating at late init we have to disable it in DT.
>
> Signed-off-by: Ivan Khoronzhuk <[email protected]>
> ---
> arch/arm/boot/dts/keystone-clocks.dtsi | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm/boot/dts/keystone-clocks.dtsi
> b/arch/arm/boot/dts/keystone-clocks.dtsi
> index 2363593..e7aea2e 100644
> --- a/arch/arm/boot/dts/keystone-clocks.dtsi
> +++ b/arch/arm/boot/dts/keystone-clocks.dtsi
> @@ -332,6 +332,7 @@ clocks {
> compatible = "ti,keystone,psc-clock";
> clocks = <&chipclk1>;
> clock-output-names = "msmcsram";
> + status = "disabled";
> reg = <0x02350038 0xb00>, <0x0235001c 0x400>;
> reg-names = "control", "domain";
> domain-id = <7>;
> --
> 1.8.3.2
>
On Thursday 30 January 2014 08:58 AM, Ivan Khoronzhuk wrote:
> Ok. I will delete node for this clock from DT and send v1
>
Sorry for the html reply first of all. That node should never have
been actually added since the clock is not suppose to be touched even
in low power states. Change log should say something like this ...
"MSMC is the coherency interconnect and all the coherent masters are
connected to it including devices which are not under Linux OS control.
MSMC clock should not be toched even in low power states."
So drop the clock node o.w without 'clk_ignore_unused' will disable
the clock leading to system stall.
I wil try get these in rc's since its a bug fix
Regards,
Santosh
Thanks, I will send v2
On 01/30/2014 04:31 PM, Santosh Shilimkar wrote:
> On Thursday 30 January 2014 08:58 AM, Ivan Khoronzhuk wrote:
>> Ok. I will delete node for this clock from DT and send v1
>>
> Sorry for the html reply first of all. That node should never have
> been actually added since the clock is not suppose to be touched even
> in low power states. Change log should say something like this ...
>
> "MSMC is the coherency interconnect and all the coherent masters are
> connected to it including devices which are not under Linux OS control.
> MSMC clock should not be toched even in low power states."
>
> So drop the clock node o.w without 'clk_ignore_unused' will disable
> the clock leading to system stall.
>
> I wil try get these in rc's since its a bug fix
>
> Regards,
> Santosh
>
>
>