On 2021-11-29 05:36, Aswath Govindraju wrote:
> Hi Peter,
>
> On 25/11/21 7:05 pm, Peter Rosin wrote:
>> Hi!
>>
>> You need to have some description on how #mux-control-cells now work.
>> The previous description is in mux-consumer.yaml and an update there
>> is needed.
>>
>> However, I have realized that the adg792a binding uses #mux-control-cells
>> to indicate if it should expose its three muxes with one mux-control
>> and operate the muxes in parallel, or if it should be expose three
>> independent mux-controls. So, the approach in this series to always
>> have the #mux-control-cells property fixed at <2> when indicating a
>> state will not work for that binding. And I see no fix for that binding
>> without adding a new property.
>>
>> So, I would like a different approach. Since I dislike how mux-controls
>> -after this series- is not (always) specifying a mux-control like the name
>> says, but instead optionally a specific state, the new property I would
>> like to add is #mux-state-cells such that it would always be one more
>> than #mux-control-cells.
>>
>> mux: mux-controller {
>> compatible = "gpio-mux";
>> #mux-control-cells = <0>;
>> #mux-state-cells = <1>;
>>
>> mux-gpios = <...>;
>> };
>>
>> can-phy {
>> compatible = "ti,tcan1043";
>> ...
>> mux-states = <&mux 1>;
>> };
>>
>> That solves the naming issue, the unused argument for mux-conrtrollers
>> that previously had #mux-control-cells = <0>, and the binding for adg792a
>> need no longer be inconsistent.
>>
>> Or, how should this be solved? I'm sure there are other options...
>>
>
>
> I feel that the new approach using mux-state-cells seems to be
> overpopulating the device tree nodes, when the state can be represented
> using the control cells. I understand that the definition for
> mux-controls is to only specify the control line to be used in a given
> mux. Can't it now be upgraded to also represent the state at which the
> control line has to be set to?
>
> With respect to adg792a, it is inline with the current implementation
> and the only change I think would be required in the driver is,
No, that does not work. See below.
>
> diff --git a/drivers/mux/adg792a.c b/drivers/mux/adg792a.c
> index e8fc2fc1ab09..2cd3bb8a40d4 100644
> --- a/drivers/mux/adg792a.c
> +++ b/drivers/mux/adg792a.c
> @@ -73,8 +73,6 @@ static int adg792a_probe(struct i2c_client *i2c)
> ret = device_property_read_u32(dev, "#mux-control-cells", &cells);
> if (ret < 0)
> return ret;
> - if (cells >= 2)
> - return -EINVAL;
>
> mux_chip = devm_mux_chip_alloc(dev, cells ? 3 : 1, 0);
When you add cell #2 with the state, the cells variable will end up
as 2 always. Which means that there is no way to alloc one mux
control since "cells ? 3 : 1" will always end up as "3", with no
easy fix.
So, your approach does not work for this driver.
Cheers,
Peter
> if (IS_ERR(mux_chip))
>
> And the following series should be compatible with it. If adg792a driver
> is the only issue then would there be any issue with only changing it
> and using this implementation?
>
> Thanks,
> Aswath
>
>
>
>
>> Cheers,
>> Peter
>>
>> On 2021-11-23 09:12, Aswath Govindraju wrote:
>>> Increase the allowed number of arguments in mux-controls to add support for
>>> passing information regarding the state of the mux to be set, for a given
>>> device.
>>>
>>> Signed-off-by: Aswath Govindraju <a-govindraju@xxxxxx>
>>> ---
>>> Documentation/devicetree/bindings/mux/gpio-mux.yaml | 2 +-
>>> Documentation/devicetree/bindings/mux/mux-controller.yaml | 2 +-
>>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.yaml b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
>>> index 0a7c8d64981a..c810b7df39de 100644
>>> --- a/Documentation/devicetree/bindings/mux/gpio-mux.yaml
>>> +++ b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
>>> @@ -26,7 +26,7 @@ properties:
>>> List of gpios used to control the multiplexer, least significant bit first.
>>>
>>> '#mux-control-cells':
>>> - const: 0
>>> + enum: [ 0, 1, 2 ]
>>>
>>> idle-state:
>>> default: -1
>>> diff --git a/Documentation/devicetree/bindings/mux/mux-controller.yaml b/Documentation/devicetree/bindings/mux/mux-controller.yaml
>>> index 736a84c3b6a5..0b4b067a97bf 100644
>>> --- a/Documentation/devicetree/bindings/mux/mux-controller.yaml
>>> +++ b/Documentation/devicetree/bindings/mux/mux-controller.yaml
>>> @@ -73,7 +73,7 @@ properties:
>>> pattern: '^mux-controller(@.*|-[0-9a-f]+)?$'
>>>
>>> '#mux-control-cells':
>>> - enum: [ 0, 1 ]
>>> + enum: [ 0, 1, 2 ]
>>>
>>> idle-state:
>>> $ref: /schemas/types.yaml#/definitions/int32
>>>
>
