linux-kernel - Re: [PATCH v2 3/5] ARM: mvebu: set SW polling as SDHCI card detection on A388-GP

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Date:	Fri, 9 Oct 2015 12:16:39 +0200
From:	Marcin Wojtas <mw@...ihalf.com>
To:	Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Cc:	linux-kernel@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
	Andrew Lunn <andrew@...n.ch>,
	Jason Cooper <jason@...edaemon.net>,
	Gregory Clément 
	<gregory.clement@...e-electrons.com>, nadavh@...vell.com,
	Lior Amsalem <alior@...vell.com>,
	Tawfik Bayouk <tawfik@...vell.com>,
	Grzegorz Jaszczyk <jaz@...ihalf.com>
Subject: Re: [PATCH v2 3/5] ARM: mvebu: set SW polling as SDHCI card detection
 on A388-GP

Hi Thomas,


2015-10-09 9:52 GMT+02:00 Thomas Petazzoni
<thomas.petazzoni@...e-electrons.com>:
> Dear Marcin Wojtas,
>
> On Fri,  9 Oct 2015 03:03:53 +0200, Marcin Wojtas wrote:
>> The newest revisions of A388-GP (v1.5 and higher) support only
>> DAT3-based card detection. Revisions < v1.5 based on GPIO detection
>> via I2C expander, but this solution is supposed to be deprecated on
>> new boards. In order to satisfy all type of hardware this commit
>> changes card detection to use software polling mechanism.
>>
>> Signed-off-by: Marcin Wojtas <mw@...ihalf.com>
>
> Can we add a comment on the DT that explains why SW polling is used,
> and which other mechanism can be used depending on the board revision?

Sure, good idea. Do you think the below would be sufficient?
sdhci@...00 {
    pinctrl-names = "default";
    pinctrl-0 = <&sdhci_pins>;
    no-1-8-v;
    /*
     * A388-GP board v1.5 and higher replace
     * hitherto card detection method based on GPIO
     * with the one using DAT3 pin. As they are
     * incompatible, software-based polling is
     * enabled with 'broken-cd' property. For boards
     * older than v1.5 it can be replaced with:
     * 'cd-gpios = <&expander0 5 GPIO_ACTIVE_LOW>;',
     * whereas for the newer ones following can be
     * used instead:
     * 'dat3-cd;'
     * 'cd-inverted;'
     */
broken-cd;
wp-inverted;
bus-width = <8>;
status = "okay";
};

Best regards,
Marcin
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