Re: [PATCH 2/6] phy: improved lookup method

Kishon Vijay Abraham I
2014-09-12T14:46:12Z

Hi,

On Friday 12 September 2014 07:37 PM, Heikki Krogerus wrote:
> On Thu, Sep 11, 2014 at 09:03:06PM +0530, Kishon Vijay Abraham I wrote:
>>> +static struct phy *phy_find(struct device *dev, const char *con_id)
>>> +{
>>> + const char *dev_id = dev ? dev_name(dev) : NULL;
>>> + int match, best_found = 0, best_possible = 0;
>>> + struct phy *phy = ERR_PTR(-ENODEV);
>>> + struct phy_lookup *p, *pl = NULL;
>>> +
>>> + if (dev_id)
>>> + best_possible += 2;
>>> + if (con_id)
>>> + best_possible += 1;
>>> +
>>> + list_for_each_entry(p, &phys, node) {
>>> + match = 0;
>>> + if (p->dev_id) {
>>> + if (!dev_id || strcmp(p->dev_id, dev_id))
>>> + continue;
>>> + match += 2;
>>> + }
>>> + if (p->con_id) {
>>> + if (!con_id || strcmp(p->con_id, con_id))
>>> + continue;
>>> + match += 1;
>>> + }
>>> +
>>> + if (match > best_found) {
>>> + pl = p;
>>> + if (match != best_possible)
>>> + best_found = match;
>>> + else
>>> + break;
>>> + }
>>> + }
>>> +
>>> + if (pl) {
>>> + struct class_dev_iter iter;
>>> + struct device *phy_dev;
>>> +
>>> + class_dev_iter_init(&iter, phy_class, NULL, NULL);
>>> + while ((phy_dev = class_dev_iter_next(&iter))) {
>>> + if (!strcmp(dev_name(phy_dev), pl->phy_name)) {
>>
>> I'm not sure how it'll work with systems which has multiple PHYs since the "id"
>> component of the device is determined purely in runtime.
>>
>> I'd assume we'll be constantly patching the lookup data for non-dt boot :-/
>
> I'm sorry but I don't think I understand (I must be a bit tired
> today)? Could you please elaborate?

Assume you have 2 phys in your system..
static struct phy_lookup usb_lookup = {
.phy_name = "phy-usb.0",
.dev_id = "usb.0",
.con_id = "usb",
};

static struct phy_lookup sata_lookup = {
.phy_name = "sata-usb.1",
.dev_id = "sata.0",
.con_id = "sata",
};

First you do modprobe phy-usb, the probe of USB PHY driver gets invoked and it
creates the PHY. The phy-core will find a free id (now it will be 0) and then
name the phy as phy-usb.0.
Then with modprobe phy-sata, the phy-core will create phy-sata.1.

This is an ideal case where the .phy_name in phy_lookup matches.

Consider if the order is flipped and the user does modprobe phy-sata first. The
phy_names won't match anymore (the sata phy device name would be "sata-usb.0").

Thanks
Kishon