Re: [PATCH v7][ 3/5] video: mx3fb: Introduce regulator support.

On 03/17/2014 07:20 AM, Sascha Hauer wrote:

On Fri, Mar 14, 2014 at 10:12:47AM +0100, Denis Carikli wrote:

quoted

+		of_property_read_string(display_np, "regulator-name",
+					&regulator_name);
+

[...]

quoted

+	/* In dt mode,
+	 * using devm_regulator_get would require that the proprety referencing
+	 * the regulator phandle has to be inside the mx3fb node.
+	 */
+	if (np) {
+		if (regulator_name)
+			mx3fbi->reg_lcd = regulator_get(NULL, regulator_name);
+
+		if (IS_ERR(mx3fbi->reg_lcd))
+			return PTR_ERR(mx3fbi->reg_lcd);
+	} else {
+		/* Permit that driver without a regulator in non-dt mode */
+		mx3fbi->reg_lcd = regulator_get(dev, "lcd");
+	}

This patch adds regulator support for the display of a i.MX3 IPU. The
problem Denis has to solve here is that he needs to get the regulator,
but the display devicenode doesn't have a struct device associated with
it, so he cannot provide one to regulator_get(). One way out here could
be a of_regulator_get(struct device_node *). Mark, would this be ok with
you?

Here, the display devicenode has no struct device associated with it 
like mentioned above.
Because of that, retriving the regulator from the devicetree, for 
instance like regulator_dev_lookup() does, would require a different 
approach.

As I understand it, what happen in regulator_dev_lookup when 
regulator_get(NULL, regulator_name) is used is the following:

Since the struct device is NULL, it skips the struct device based 
lookup, but also the devicetree lookup (it uses dev->of_node for that)
At the end it falls back on a match on the regulator name to find it.

would keeping regulator_get(NULL, regulator_name); in the driver instead 
be better for now?

Denis.