[U-Boot] [PATCH v1] mmc: sdhci: SDHCI controllers also need power

[Andy Shevchenko]

On Thu, Apr 6, 2017 at 6:44 AM, Simon Glass <sjg at chromium.org> wrote:
> On 1 April 2017 at 07:11, Andy Shevchenko
> <andriy.shevchenko at linux.intel.com> wrote:
>> On Fri, 2017-03-31 at 22:24 -0600, Simon Glass wrote:
>>> On 20 March 2017 at 06:51, Andy Shevchenko
>>> <andriy.shevchenko at linux.intel.com> wrote:
>>> > On Sun, 2017-03-19 at 20:30 -0600, Simon Glass wrote:
>>> > > On 15 March 2017 at 12:25, Andy Shevchenko
>>> > > <andriy.shevchenko at linux.intel.com> wrote:

>>> > > > +       board_mmc_power_init();

>>> > > You should be using driver model for this (CONFIG_DM_MMC*).
>>> >
>>> > I didn't get this part. It's used by the driver (tangier_sdhci) as
>>> > far
>>> > as I understand.

>> Oh, we are talking about host controller's power management which is
>> done using PMU (power management unit) inside SoC. It's *not* a power
>> regulator.
>>
>> Above is clearly about card power management, which we also have (in
>> case of Wi-Fi), but it's not applicable for eMMC soldered on the module.
>
> Still if the eMMC is soldered on, it needs power, right? What is the
> distinction?

It's irrelevant to this patch and discussion.

> In any case we cannot call board code from the driver with DM - it's
> just not how things work. So can you init it in your board_init() code
> perhaps, if you can't use a power driver?

I didn't get this either.

It means that PMU driver should *not* go with DM model then or what?

>>> > >  or do this in
>>> > > the board code.
>>> >
>>> > How? It's already board code that powers on the controller. If you
>>> > look
>>> > at mmc_init() it does this. SDHCI on the other hand doesn't which is
>>> > for
>>> > my opinion is a bug. Otherwise why is the difference between
>>> > initialization sequence of MMC and SHDCI controllers?
>>>
>>> There should not really be a different I think, except that with
>>> driver model we want to use drivers for power rather than hard-coding
>>> things in custom code.
>>
>> I totally agree with this, though since we have no clear PCI
>> implementation on that board (*) we can't have good described PCI power
>> management for it.
>>
>> (*) It's called "fake PCI" meaning it mimics PCI programming interface
>> while being not 100% compatible with PCI specification on hardware and
>> firmware levels.
>>
>> So, for now I have been seeing no alternatives than my initial approach,
>> though I'm all ears for better solution.
>

> Well you can create a regulator driver which has a single regulator to
> handle whatever needs doing to enable MMC power.

No. It looks like you are mixing two power controls: card itself and
host controller. They are using quite different mechanisms to be
powered on.
We are talking here about *host* controller power flow.

And still there is no clarification why MMC flow calls board code and
on the other hand you made an objectiion to do the same for SDHCI.

I still do not see better solution as mine initial one, otherwise
above question should be clarified first.

-- 
With Best Regards,
Andy Shevchenko