[U-Boot] [PATCH v2 15/40] power: Add AMS AS3722 PMIC support

[Thierry Reding]

On Wed, Aug 27, 2014 at 07:26:12AM +0200, Heiko Schocher wrote:
> Hello Thierry,
> 
> Am 26.08.2014 17:34, schrieb Thierry Reding:
[...]
> >+int as3722_init(struct as3722 **pmicp, const void *fdt)
> >+{
> >+	struct as3722 *pmic =&as3722_pmic;
> >+	int count, nodes[1], i;
> >+	int err;
> >+
> >+	count = fdtdec_find_aliases_for_id(fdt, NULL, COMPAT_AMS_AS3722,
> >+					   nodes, ARRAY_SIZE(nodes));
> >+	for (i = 0; i<  count; i++) {
> >+		int parent = fdt_parent_offset(fdt, nodes[i]), bus;
> >+		struct i2c_adapter *adapter;
> >+		fdt_addr_t address;
> >+		u8 id, revision;
> >+
> >+		bus = i2c_get_bus_num_fdt(parent);
> >+		if (bus<  0) {
> >+			error("invalid bus %d", bus);
> >+			continue;
> >+		}
> >+
> >+		address = fdtdec_get_addr(fdt, nodes[i], "reg");
> >+		if (address == FDT_ADDR_T_NONE) {
> >+			error("slave address not found");
> >+			continue;
> >+		}
> >+
> >+		adapter = i2c_adapter_get(bus);
> >+		if (!adapter) {
> >+			error("I2C adapter for bus %d not found", bus);
> >+			continue;
> >+		}
> 
> Why is i2c_set_bus_num() not enough for you? Why introducing a new
> API? If another uses this PMIC behind a i2c mux, this driver maybe
> not work correctly.

As I explained earlier, I think requiring users to manually micro-manage
the I2C busses is a bad idea. It's very tedious and error prone. It does
also mean that every patch needs to be carefully checked that the I2C
API is used correctly. The intent of the i2c_client API was to introduce
a higher-level object that people can use and that does the bulk of the
work behind the scenes rather than duplicating it all over the place. It
is true that perhaps it currently doesn't work well with I2C muxes. But
the advantage is that when it does, it does so for everybody that uses
it.

Thierry
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