On Tue, Dec 17, 2019 at 02:57:33PM +0900, Chanwoo Choi wrote:
> In order to remove the deprecated 'devfreq' property, replace with
> new 'exynos,parent-bus' property in order to get the parent devfreq device
> in devicetree file instead of 'devfreq' property. But, to guarantee the
> backward-compatibility, keep the support 'devfreq' property.
>
> Signed-off-by: Chanwoo Choi <[email protected]>
> ---
> .../bindings/devfreq/exynos-bus.txt | 16 +++++++--------
> drivers/devfreq/exynos-bus.c | 20 ++++++++++++-------
> 2 files changed, 21 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> index e71f752cc18f..c948cee01124 100644
> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> @@ -45,7 +45,7 @@ Required properties only for parent bus device:
> of buses.
>
> Required properties only for passive bus device:
> -- devfreq: the parent bus device.
> +- exynos,parent-bus: the parent bus device.
If you are going to do something new, why not use the interconnect
binding here?
Rob
On 12/27/19 6:01 AM, Rob Herring wrote:
> On Tue, Dec 17, 2019 at 02:57:33PM +0900, Chanwoo Choi wrote:
>> In order to remove the deprecated 'devfreq' property, replace with
>> new 'exynos,parent-bus' property in order to get the parent devfreq device
>> in devicetree file instead of 'devfreq' property. But, to guarantee the
>> backward-compatibility, keep the support 'devfreq' property.
>>
>> Signed-off-by: Chanwoo Choi <[email protected]>
>> ---
>> .../bindings/devfreq/exynos-bus.txt | 16 +++++++--------
>> drivers/devfreq/exynos-bus.c | 20 ++++++++++++-------
>> 2 files changed, 21 insertions(+), 15 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>> index e71f752cc18f..c948cee01124 100644
>> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>> @@ -45,7 +45,7 @@ Required properties only for parent bus device:
>> of buses.
>>
>> Required properties only for passive bus device:
>> -- devfreq: the parent bus device.
>> +- exynos,parent-bus: the parent bus device.
>
> If you are going to do something new, why not use the interconnect
> binding here?
As I knew, interconnect make the data path among multiple nodes
and set the average and peak bandwidth to the specific data path.
It means that some data will be flowed from node_a to node_d
or the reverse way because each node has the tightly coupled
dependency for data flow.
node_a <-> node_b <-> node_c <-> node_d
On the other hand, exynos-bus.c driver is not related to 'data path'.
Each bus just need to control the their own frequency and voltage.
But, share the power line (regulator) between exynos-bus device
even if there are no any dependency of data flow.
'exynos,parent-bus' property just indicate the specific
devfreq device(parent bus device) which controls
the shared power line(regulator) in order to prevent
the h/w problem due to the wrong pair of frequency and voltage.
'exynos,parent-bus' property is only used to catch
the change timing of shared power line.
And,
as you commented, there are some data path among the exynos-bus
devices for the display h/w as following:
bus_display -> bus_leftbus -> bus_dmc
In order to make the data path between bus devices,
interconnect binding is required. This approach[1] was posted.
[1] https://patchwork.kernel.org/cover/11305265/
- [RFC,v3,0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect
--
Best Regards,
Chanwoo Choi
Samsung Electronics
Hi Rob,
Gently Ping.
On 12/27/19 9:09 AM, Chanwoo Choi wrote:
> On 12/27/19 6:01 AM, Rob Herring wrote:
>> On Tue, Dec 17, 2019 at 02:57:33PM +0900, Chanwoo Choi wrote:
>>> In order to remove the deprecated 'devfreq' property, replace with
>>> new 'exynos,parent-bus' property in order to get the parent devfreq device
>>> in devicetree file instead of 'devfreq' property. But, to guarantee the
>>> backward-compatibility, keep the support 'devfreq' property.
>>>
>>> Signed-off-by: Chanwoo Choi <[email protected]>
>>> ---
>>> .../bindings/devfreq/exynos-bus.txt | 16 +++++++--------
>>> drivers/devfreq/exynos-bus.c | 20 ++++++++++++-------
>>> 2 files changed, 21 insertions(+), 15 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>>> index e71f752cc18f..c948cee01124 100644
>>> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>>> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
>>> @@ -45,7 +45,7 @@ Required properties only for parent bus device:
>>> of buses.
>>>
>>> Required properties only for passive bus device:
>>> -- devfreq: the parent bus device.
>>> +- exynos,parent-bus: the parent bus device.
>>
>> If you are going to do something new, why not use the interconnect
>> binding here?
>
> As I knew, interconnect make the data path among multiple nodes
> and set the average and peak bandwidth to the specific data path.
>
> It means that some data will be flowed from node_a to node_d
> or the reverse way because each node has the tightly coupled
> dependency for data flow.
>
> node_a <-> node_b <-> node_c <-> node_d
>
>
> On the other hand, exynos-bus.c driver is not related to 'data path'.
> Each bus just need to control the their own frequency and voltage.
> But, share the power line (regulator) between exynos-bus device
> even if there are no any dependency of data flow.
>
> 'exynos,parent-bus' property just indicate the specific
> devfreq device(parent bus device) which controls
> the shared power line(regulator) in order to prevent
> the h/w problem due to the wrong pair of frequency and voltage.
>
> 'exynos,parent-bus' property is only used to catch
> the change timing of shared power line.
>
>
> And,
> as you commented, there are some data path among the exynos-bus
> devices for the display h/w as following:
>
> bus_display -> bus_leftbus -> bus_dmc
>
> In order to make the data path between bus devices,
> interconnect binding is required. This approach[1] was posted.
> [1] https://patchwork.kernel.org/cover/11305265/
> - [RFC,v3,0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect
>
Are there any other commentss?
--
Best Regards,
Chanwoo Choi
Samsung Electronics
Hi Rob,
On Mon, Jan 6, 2020 at 10:32 AM Chanwoo Choi <[email protected]> wrote:
>
> Hi Rob,
>
> Gently Ping.
Once again, ping. Could you please review?
On v2[1], made separate patches for dt-binding.
[1] https://patchwork.kernel.org/cover/11304545/
>
> On 12/27/19 9:09 AM, Chanwoo Choi wrote:
> > On 12/27/19 6:01 AM, Rob Herring wrote:
> >> On Tue, Dec 17, 2019 at 02:57:33PM +0900, Chanwoo Choi wrote:
> >>> In order to remove the deprecated 'devfreq' property, replace with
> >>> new 'exynos,parent-bus' property in order to get the parent devfreq device
> >>> in devicetree file instead of 'devfreq' property. But, to guarantee the
> >>> backward-compatibility, keep the support 'devfreq' property.
> >>>
> >>> Signed-off-by: Chanwoo Choi <[email protected]>
> >>> ---
> >>> .../bindings/devfreq/exynos-bus.txt | 16 +++++++--------
> >>> drivers/devfreq/exynos-bus.c | 20 ++++++++++++-------
> >>> 2 files changed, 21 insertions(+), 15 deletions(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> >>> index e71f752cc18f..c948cee01124 100644
> >>> --- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> >>> +++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
> >>> @@ -45,7 +45,7 @@ Required properties only for parent bus device:
> >>> of buses.
> >>>
> >>> Required properties only for passive bus device:
> >>> -- devfreq: the parent bus device.
> >>> +- exynos,parent-bus: the parent bus device.
> >>
> >> If you are going to do something new, why not use the interconnect
> >> binding here?
> >
> > As I knew, interconnect make the data path among multiple nodes
> > and set the average and peak bandwidth to the specific data path.
> >
> > It means that some data will be flowed from node_a to node_d
> > or the reverse way because each node has the tightly coupled
> > dependency for data flow.
> >
> > node_a <-> node_b <-> node_c <-> node_d
> >
> >
> > On the other hand, exynos-bus.c driver is not related to 'data path'.
> > Each bus just need to control the their own frequency and voltage.
> > But, share the power line (regulator) between exynos-bus device
> > even if there are no any dependency of data flow.
> >
> > 'exynos,parent-bus' property just indicate the specific
> > devfreq device(parent bus device) which controls
> > the shared power line(regulator) in order to prevent
> > the h/w problem due to the wrong pair of frequency and voltage.
> >
> > 'exynos,parent-bus' property is only used to catch
> > the change timing of shared power line.
> >
> >
> > And,
> > as you commented, there are some data path among the exynos-bus
> > devices for the display h/w as following:
> >
> > bus_display -> bus_leftbus -> bus_dmc
> >
> > In order to make the data path between bus devices,
> > interconnect binding is required. This approach[1] was posted.
> > [1] https://patchwork.kernel.org/cover/11305265/
> > - [RFC,v3,0/7] PM / devfreq: Simple QoS for exynos-bus using interconnect
> >
>
> Are there any other commentss?
>
>
> --
> Best Regards,
> Chanwoo Choi
> Samsung Electronics
--
Best Regards,
Chanwoo Choi