netdev - Re: [PATCH] Make EN2 pin optional in the TRF7970A driver

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Date:   Mon, 13 Feb 2017 07:38:12 +0100
From:   Heiko Schocher <hs@...x.de>
To:     Rob Herring <robh@...nel.org>
Cc:     netdev@...r.kernel.org, Guan Ben <ben.guan@...bosch.com>,
        Mark Jonas <mark.jonas@...bosch.com>,
        devicetree@...r.kernel.org, linux-wireless@...r.kernel.org,
        linux-kernel@...r.kernel.org, Samuel Ortiz <sameo@...ux.intel.com>,
        Lauro Ramos Venancio <lauro.venancio@...nbossa.org>,
        Aloisio Almeida Jr <aloisio.almeida@...nbossa.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] Make EN2 pin optional in the TRF7970A driver

Hello Rob,

Am 10.02.2017 um 16:51 schrieb Rob Herring:
> On Tue, Feb 07, 2017 at 06:22:04AM +0100, Heiko Schocher wrote:
>> From: Guan Ben <ben.guan@...bosch.com>
>>
>> Make the EN2 pin optional. This is useful for boards,
>> which have this pin fix wired, for example to ground.
>>
>> Signed-off-by: Guan Ben <ben.guan@...bosch.com>
>> Signed-off-by: Mark Jonas <mark.jonas@...bosch.com>
>> Signed-off-by: Heiko Schocher <hs@...x.de>
>>
>> ---
>>
>>   .../devicetree/bindings/net/nfc/trf7970a.txt       |  4 ++--
>>   drivers/nfc/trf7970a.c                             | 26 ++++++++++++----------
>>   2 files changed, 16 insertions(+), 14 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
>> index 32b35a0..5889a3d 100644
>> --- a/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
>> +++ b/Documentation/devicetree/bindings/net/nfc/trf7970a.txt
>> @@ -5,8 +5,8 @@ Required properties:
>>   - spi-max-frequency: Maximum SPI frequency (<= 2000000).
>>   - interrupt-parent: phandle of parent interrupt handler.
>>   - interrupts: A single interrupt specifier.
>> -- ti,enable-gpios: Two GPIO entries used for 'EN' and 'EN2' pins on the
>> -  TRF7970A.
>> +- ti,enable-gpios: One or two GPIO entries used for 'EN' and 'EN2' pins on the
>> +  TRF7970A. EN2 is optional.
>
> Could EN ever be optional/fixed? If so, perhaps deprecate this property
> and do 2 properties, one for each pin.

The hardware I have has the EN2 pin fix connected to ground. Looking
into http://www.ti.com/lit/ds/slos743k/slos743k.pdf page 19 table 6-3
and 6-4 the EN2 pin is a don;t core if EN = 1. If EN = 0 EN2 pin
selects between Power Down and Sleep Mode ... I see no reason why
this is not possible/allowed ...

Hmm.. I do not like the idea of deprecating the "ti,enable-gpios"
property into 2 seperate properties ... but if this would be a reason
for not accepting this patch, I can do this ... How should I name
the 2 new properties?

"ti,pin-enable"  and "ti,pin-enable2" ?

bye,
Heiko
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