On Mon, Jul 10, 2017 at 6:06 PM, Darren Hart <dvhart@xxxxxxxxxxxxx> wrote:
> On Mon, Jul 10, 2017 at 05:20:43PM +0300, Andy Shevchenko wrote:
>> On Mon, 2017-07-10 at 16:15 +0200, Carlo Caione wrote:
>> > Hi,
>> > We are working on an Asus Z550M shipping a baytrail processor. From
>> > the 4.11 kernel we noticed that the system is not bootable anymore
>> > since it hangs during boot when probing the r8169 driver, not even a
>> > trace is available.
>> >
>> > We bisected this problem down to commit 282a4e4 ("platform/x86: Enable
>> > Atom PMC platform clocks").
>> >
>> > We suspected that the problem is that one of the PMC clocks is being
>> > used by the Ethernet board as XTAL clock and since it is not
>> > explicitly claimed by the driver, it is gated at boot by the clock
>> > framework, causing the system to hang.
>> >
>> > We have a quirk downstream in place where we basically modified the
>> > r8169 driver to claim the 25MHz pmc_plt_clk_4 clock, and this seems to
>> > work fine, but we really want to find a more upstreamable and
>> > definitive solution.
>>
>> Can you copy in-place the hack patch you have?
>>
>> > The best solution would probably be avoiding to gate the clocks at all
>> > when booting if these are being already used by the firmware, but IIUC
>> > this information is not always available in the enable clock register.
>>
>> Yes, sounds sane.
>
> Looking back, I've seen two instances that appear related to this patch
> series. This one, and the one reported by Enric (on Cc) regarding the
> Acer C200 audio.
>
> Enric, did your issue get resolved?
>
> In those two cases, are we able to determine programmatically if the
> clock is already in use by the firmware? (via the enabled register I
> presume?)
Just tested this and the answer is no.
__clk_is_enabled() on the pmc_plt_clk_4 clock before
clk_prepare_enable() returns 0.
--
Carlo Caione | +39.340.80.30.096 | Endless
