Re: [E1000-devel] igb driver with Intel Atom Bay Trail issue

[Hans de G. <hde...@re...>]

Hi Andy,

On 28-03-19 15:58, Andy Shevchenko wrote:
> On Thu, Mar 28, 2019 at 03:35:58PM +0100, David Müller wrote:
>> Andy Shevchenko wrote:
>>> On Wed, Mar 27, 2019 at 06:31:19PM +0100, David Müller wrote:
>>>> The pmc_plt_clks may also be used for external hardware purposes without
>>>> the need for a driver involved. So I'm afraid a fix similar to the r8169
>>>> approach will not suit all needs. Please see
>>>> https://www.spinics.net/lists/linux-clk/msg35800.html for details.
>>>
>>> Any driver for device which is using PMC clock should take it into
>>> consideration.
>>
>> I agree that each driver should properly request the clocks and other
>> resources needed.
>>
>> But what if the PMC clock is used by hardware for which no driver is
>> being loaded or needed?
> 
> Perhaps I didn't get a full picture.
> 
> In the original message you referred to igb _driver_ and devices that are not
> working properly after resume.
> 
> The igb driver patching can fix that, right?
> 
> If the driver is not loaded, then the clock is not in use and can be gated,
> correct?
> 
> If there is a connection of this clock to the hardware which is served by
> firmware, then its firmware's deal, no?
> 
> Can you elaborate a bit more the case you are talking about?

In David's case we are talking about a USB hub which needs a pmc-clk
(yes really). Also see me other mail I send about this about 5 minutes
ago.

David's case is the reason why I believe we need a DMI quirk table; and
once we have that I think the board with igb ethernet controllers might
just as well be handled the same way (I already checked it has usable
DMI identifying info).

Regards,

Hans