linux-kernel - Re: [PATCH 1/3] dt-bindings: mmc: sdhci-am654: Update Output tap delay binding

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Date:   Thu, 20 Feb 2020 16:54:00 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     Rob Herring <robh@...nel.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-mmc@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <ulf.hansson@...aro.org>,
        <adrian.hunter@...el.com>
Subject: Re: [PATCH 1/3] dt-bindings: mmc: sdhci-am654: Update Output tap
 delay binding

Rob,

On 14/02/20 4:28 pm, Faiz Abbas wrote:
> Rob,
> 
> On 07/02/20 3:07 pm, Faiz Abbas wrote:
>> Rob,
>>
>> On 20/01/20 11:00 am, Faiz Abbas wrote:
>>> Hi Rob,
>>>
>>> On 15/01/20 7:20 am, Rob Herring wrote:
>>>> On Wed, Jan 08, 2020 at 08:39:18PM +0530, Faiz Abbas wrote:
>>>>> According to latest AM65x Data Manual[1], a different output tap delay
>>>>> value is recommended for all speed modes. Therefore, replace the
>>>>> ti,otap-del-sel binding with one ti,otap-del-sel- for each MMC/SD speed
>>>>> mode.
>>>>>
>>>>> [1] http://www.ti.com/lit/gpn/am6526
>>>>>
>>>>> Signed-off-by: Faiz Abbas <faiz_abbas@...com>
>>>>> ---
>>>>>  .../devicetree/bindings/mmc/sdhci-am654.txt   | 21 +++++++++++++++++--
>>>>>  1 file changed, 19 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/Documentation/devicetree/bindings/mmc/sdhci-am654.txt b/Documentation/devicetree/bindings/mmc/sdhci-am654.txt
>>>>> index 50e87df47971..c6ccecb9ae5a 100644
>>>>> --- a/Documentation/devicetree/bindings/mmc/sdhci-am654.txt
>>>>> +++ b/Documentation/devicetree/bindings/mmc/sdhci-am654.txt
>>>>> @@ -18,7 +18,20 @@ Required Properties:
>>>>>  	- clocks: Handles to the clock inputs.
>>>>>  	- clock-names: Tuple including "clk_xin" and "clk_ahb"
>>>>>  	- interrupts: Interrupt specifiers
>>>>> -	- ti,otap-del-sel: Output Tap Delay select
>>>>> +	Output tap delay for each speed mode:
>>>>> +	- ti,otap-del-sel-legacy
>>>>> +	- ti,otap-del-sel-mmc-hs
>>>>> +	- ti,otap-del-sel-sd-hs
>>>>> +	- ti,otap-del-sel-sdr12
>>>>> +	- ti,otap-del-sel-sdr25
>>>>> +	- ti,otap-del-sel-sdr50
>>>>> +	- ti,otap-del-sel-sdr104
>>>>> +	- ti,otap-del-sel-ddr50
>>>>> +	- ti,otap-del-sel-ddr52
>>>>> +	- ti,otap-del-sel-hs200
>>>>> +	- ti,otap-del-sel-hs400
>>>>> +	  These bindings must be provided otherwise the driver will disable the
>>>>> +	  corresponding speed mode (i.e. all nodes must provide at least -legacy)
>>>>
>>>> Why not just extend the existing property to be an array. We already 
>>>> have properties to enable/disable speed modes.
>>>>
>>>
>>> Its hard to keep track of which modes have values and which don't when
>>> you add an array. This scheme is just easier on anyone adding new values
>>> or updating old values.
>>>
>>> We already disable speed modes based on platform specific properties in
>>> other drivers. In sdhci-omap.c, the driver disables the corresponding
>>> speed mode if the corresponding pinmux and iodelay values are not populated.
>>>
>>
>> Do you agree on above?
>>
> 
> Gentle ping.
> 

Ping.

Thanks,
Faiz