diff mbox series

[v4,1/3] arm64: dts: qcom: sc7280: Add proxy interconnect requirements for modem

Message ID 1652978825-5304-2-git-send-email-quic_sibis@quicinc.com (mailing list archive)
State New
Headers show
Series Add support for proxy interconnect bandwidth votes | expand

Commit Message

Sibi Sankar May 19, 2022, 4:47 p.m. UTC
Add interconnects that are required to be proxy voted upon during modem
bootup on SC7280 SoCs.

Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
---
 arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi | 1 +
 1 file changed, 1 insertion(+)

Comments

Bjorn Andersson May 19, 2022, 8:35 p.m. UTC | #1
On Thu 19 May 09:47 PDT 2022, Sibi Sankar wrote:

> Add interconnects that are required to be proxy voted upon during modem
> bootup on SC7280 SoCs.

This looks reasonable, but how come the vote is only for DDR frequency?
What about the buses between modem and ddr?

Regards,
Bjorn

> 
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
> ---
>  arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
> index 9f4a9c263c35..91aad86cc708 100644
> --- a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
> @@ -88,6 +88,7 @@
>  	status = "okay";
>  	compatible = "qcom,sc7280-mss-pil";
>  	iommus = <&apps_smmu 0x124 0x0>, <&apps_smmu 0x488 0x7>;
> +	interconnects = <&mc_virt MASTER_LLCC 0 &mc_virt SLAVE_EBI1 0>;
>  	memory-region = <&mba_mem>, <&mpss_mem>;
>  };
>  
> -- 
> 2.7.4
>
Sibi Sankar May 20, 2022, 6:08 p.m. UTC | #2
Hey Bjorn,
Thanks for taking time to review the series.

On 5/20/22 2:05 AM, Bjorn Andersson wrote:
> On Thu 19 May 09:47 PDT 2022, Sibi Sankar wrote:
> 
>> Add interconnects that are required to be proxy voted upon during modem
>> bootup on SC7280 SoCs.
> 
> This looks reasonable, but how come the vote is only for DDR frequency?
> What about the buses between modem and ddr?

The proxy votes that are put in aren't for perf related reasons, the
modem was getting llcc timeouts while trying to read contents from 
memory. The hw team recommended the proxy votes as the fix.

-Sibi

> 
> Regards,
> Bjorn
> 
>>
>> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
>> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
>> Signed-off-by: Sibi Sankar <quic_sibis@quicinc.com>
>> ---
>>   arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
>> index 9f4a9c263c35..91aad86cc708 100644
>> --- a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
>> @@ -88,6 +88,7 @@
>>   	status = "okay";
>>   	compatible = "qcom,sc7280-mss-pil";
>>   	iommus = <&apps_smmu 0x124 0x0>, <&apps_smmu 0x488 0x7>;
>> +	interconnects = <&mc_virt MASTER_LLCC 0 &mc_virt SLAVE_EBI1 0>;
>>   	memory-region = <&mba_mem>, <&mpss_mem>;
>>   };
>>   
>> -- 
>> 2.7.4
>>
Stephen Boyd May 20, 2022, 7:07 p.m. UTC | #3
Quoting Sibi Sankar (2022-05-20 11:08:52)
> Hey Bjorn,
> Thanks for taking time to review the series.
>
> On 5/20/22 2:05 AM, Bjorn Andersson wrote:
> > On Thu 19 May 09:47 PDT 2022, Sibi Sankar wrote:
> >
> >> Add interconnects that are required to be proxy voted upon during modem
> >> bootup on SC7280 SoCs.
> >
> > This looks reasonable, but how come the vote is only for DDR frequency?
> > What about the buses between modem and ddr?
>
> The proxy votes that are put in aren't for perf related reasons, the
> modem was getting llcc timeouts while trying to read contents from
> memory. The hw team recommended the proxy votes as the fix.

Presumably the bootloader sets up some initial modem and ddr bus
bandwidth requests? Or the modem bootloader stage (MSA?) handles that
part?
Sibi Sankar May 26, 2022, 11:16 a.m. UTC | #4
On 5/21/22 12:37 AM, Stephen Boyd wrote:
> Quoting Sibi Sankar (2022-05-20 11:08:52)
>> Hey Bjorn,
>> Thanks for taking time to review the series.
>>
>> On 5/20/22 2:05 AM, Bjorn Andersson wrote:
>>> On Thu 19 May 09:47 PDT 2022, Sibi Sankar wrote:
>>>
>>>> Add interconnects that are required to be proxy voted upon during modem
>>>> bootup on SC7280 SoCs.
>>>
>>> This looks reasonable, but how come the vote is only for DDR frequency?
>>> What about the buses between modem and ddr?
>>
>> The proxy votes that are put in aren't for perf related reasons, the
>> modem was getting llcc timeouts while trying to read contents from
>> memory. The hw team recommended the proxy votes as the fix.
> 
> Presumably the bootloader sets up some initial modem and ddr bus
> bandwidth requests? Or the modem bootloader stage (MSA?) handles that
> part?

Stephen/Bjorn,
Sorry for the delay, took a while to dig this up. The modem interconnect
is connected directly to gemnoc ddr. The path info from modem --> ddr is
split up into modem --> llcc and llcc --> ddr (Similar to CPUs) i.e. in
the end scaling of the path involves scaling of the two clocks, gemnoc
and ddr. There isn't any default vote for modem --> llcc as such but it
gets implicitly scaled when we vote max for llcc --> ddr path due to
dependency maintained between the two clocks by rpmh.

-Sibi

>
diff mbox series

Patch

diff --git a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
index 9f4a9c263c35..91aad86cc708 100644
--- a/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7280-chrome-common.dtsi
@@ -88,6 +88,7 @@ 
 	status = "okay";
 	compatible = "qcom,sc7280-mss-pil";
 	iommus = <&apps_smmu 0x124 0x0>, <&apps_smmu 0x488 0x7>;
+	interconnects = <&mc_virt MASTER_LLCC 0 &mc_virt SLAVE_EBI1 0>;
 	memory-region = <&mba_mem>, <&mpss_mem>;
 };