[U-Boot] [PATCH 1/2] ARM: tegra: Add e2220-1170 board

[Stephen Warren]

On 07/30/2015 12:23 PM, Simon Glass wrote:
> Hi Stephen,
>
> On 30 July 2015 at 12:13, Stephen Warren <swarren at wwwdotorg.org> wrote:
>> On 07/29/2015 05:02 PM, Simon Glass wrote:
>>>
>>> Hi Stephen,
>>>
>>> On 29 July 2015 at 13:48, Stephen Warren <swarren at wwwdotorg.org> wrote:

>>>> diff --git a/board/nvidia/e2220-1170/e2220-1170.c
>>>> b/board/nvidia/e2220-1170/e2220-1170.c
>>
>>>> +void pin_mux_mmc(void)
>>>> +{
>>>> +       struct udevice *dev;
>>>> +       uchar val;
>>>> +       int ret;
>>>> +
>>>> +       /* Turn on MAX77620 LDO2 to 3.3V for SD card power */
>>>> +       ret = i2c_get_chip_for_busnum(0, 0x3c, 1, &dev);
>>>> +       if (ret) {
>>>> +               printf("%s: Cannot find MAX77620 I2C chip\n", __func__);
>>>> +               return;
>>>> +       }
>>>> +       val = 0xf2;
>>>> +       ret = dm_i2c_write(dev, 0x27, &val, 1);
>>>> +       if (ret)
>>>> +               printf("i2c_write 0 0x3c 0x27 failed: %d\n", ret);
>>>
>>>
>>> Shouldn't this be in a PMIC driver?
>>
>>
>> I think the overall amount of code contained in U-Boot ends up being a lot
>> smaller this way; it simply and directly performs some necessary I2C writes,
>> and V2 contains better comments describing the operation. This avoids all
>> the overhead of creating a PMIC driver and instantiating it etc. This code
>> is also consistent in style with many other Tegra boards. I'm rather
>> inclined to leave this as-is unless there's some particular advantage you
>> can state to creating a PMIC driver (I had thought of that original, but
>> shied away from the large overhead/infrastructure involved with that.)
>
> If this is the only write that happens to the PMIC then that is fine.
> But when you add other things, won't we need to adjust more things?

I believe for the set of peripherals we're likely to support in U-Boot, 
this is enough. On the off-chance we add HDMI or USB3 host support, 
perhaps we'll need more regulators, but that's not something that's 
likely to happen soon.