Re: [PATCH] mfd: qcom-spmi-pmic: Add support for more chips versions

On 11/6/2014 12:54 AM, Ivan T. Ivanov wrote:

On Wed, 2014-11-05 at 17:36 -0800, Bjorn Andersson wrote:

quoted

On Wed, Nov 5, 2014 at 10:31 AM, Ivan T. Ivanov [off-list ref] wrote:

quoted

On Wed, 2014-11-05 at 10:11 -0800, Bjorn Andersson wrote:

quoted

On Tue, Nov 4, 2014 at 5:33 AM, Ivan T. Ivanov [off-list ref]
wrote:
[..]

quoted

@@ -28,11 +144,27 @@ static int pmic_spmi_probe(struct spmi_device

*sdev)
  {
         struct device_node *root = sdev->dev.of_node;
         struct regmap *regmap;
+       struct property *prop;
+       int major, minor, ret;
+       char *name, compatible[32];

         regmap = devm_regmap_init_spmi_ext(sdev,
&spmi_regmap_config);

Hi Ivan, I have a general question about this driver/layer.
Since the driver is using regmap, why does it need to be 
qcom-*spmi*-pmic ? could we drop the spmi part?
regmap's point is abstraction of  the bus technology, and indeed some 
PMICs use i2c.

quoted

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         if (IS_ERR(regmap))
                 return PTR_ERR(regmap);

+       ret = pmic_spmi_read_revid(regmap, &name, &major, &minor);
+       if (!ret) {
+               snprintf(compatible, ARRAY_SIZE(compatible),
"qcom,%s-v%d.%d",
+                        name, major, minor);
+               prop = kzalloc(sizeof(*prop), GFP_KERNEL);
+               if (prop) {
+                       prop->name = kstrdup("compatible",
GFP_KERNEL);
+                       prop->value = kstrdup(compatible,
GFP_KERNEL);
+                       prop->length = strlen(prop->value);
+                       of_update_property(root, prop);
+               }
+       }
+

Why would you do this?
What benefit does it give to patch the of_node to have a more
specific
compatible?

Some of the child device drivers have to know PMIC chip revision.

So your plan is to have a strstr(parent->compatible, "-v2") there?

Actually also PMIC subtype (pm8841, pm8226...) is also required, so
the plan is to have something like this:

{
         static const struct of_device_id pmic_match_table[] = {
                 { .compatible = "qcom,pm8941-v1.0" },
                 { .compatible = "qcom,pm8841-v0.0" },
                 { }

         };

         const struct of_device_id *match;

         match = of_match_device(pmic_match_table, pdev->dev.parent);
         if (match) {
                 dev_info(&pdev->dev, "%s chip detected\n", match->compatible);
         }
}

quoted

Could you be a little bit more elaborate on what you're trying to do
and which child devices that might be?

For example ADC drivers are required temperature compensation based
on PMIC variant and chip manufacturer.

This patch have one issue, at least :-). Using of_update_property will prevent
driver to be build as module. which, I think, is coming from the fact the
on first load it will modify device compatible property and will be impossible
driver to match device id again. Still thinking how to overcome this.

Regards,
Ivan
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