From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: [PATCH 2/2] mmc: sdhci: DT: Allow to specify that no write protect signal is present Date: Tue, 05 May 2015 11:04:48 +0200 Message-ID: <554887B0.4020407@metafoo.de> References: <1430214020-16816-1-git-send-email-lars@metafoo.de> <1430214020-16816-2-git-send-email-lars@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Ulf Hansson Cc: Mike Looijmans , linux-mmc , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala List-Id: devicetree@vger.kernel.org On 05/05/2015 10:36 AM, Ulf Hansson wrote: [...] >> diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt >> index 438899e..b068549 100644 >> --- a/Documentation/devicetree/bindings/mmc/mmc.txt >> +++ b/Documentation/devicetree/bindings/mmc/mmc.txt >> @@ -21,6 +21,7 @@ Optional properties: >> below for the case, when a GPIO is used for the CD line >> - wp-inverted: when present, polarity on the WP line is inverted. See the note >> below for the case, when a GPIO is used for the WP line >> +- disable-wp: When set no physical WP line is present > > This requires some additional explanation, I believe. I assume this > property is only relevant for those controllers that have internal > logic to handle WP!? Yes, currently drivers for controllers that have a built-in WP detection logic typically assume that if no WP GPIO is specified the built-in WP logic should be used. But for some of them the value returned by the internal detection logic will be bogus if there is no WP signal connected. So we need a way to specify that that there is no WP signal and the internal detection logic shouldn't be used either. > > For those that uses GPIO, this can't ever be a correct configuration. Right? It wouldn't make much sense to use it with a GPIO based detection logic, since you simply don't specify the wp-gpio property if it is not present. One the other hand it wouldn't cause any harm to specify it in addition to not specifying the wp-gpios property. How about: - disable-wp: When set no physical WP line is present. This property should only be specified when the controller has a dedicated write-protect detection logic. If a GPIO is used for write-protect detection logic is used it is sufficient to not specify wp-gpios property in the absence of a WP line. [...] -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html