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.
[...]
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