Re: Reviving the LPSS PWM patches

From: "Kumar, Shobhit" <shobhit.kumar@linux.intel.com>
To: "Lluís Batlle i Rossell" <viric@viric.name>
Cc: russianneuromancer@ya.ru, intel-gfx@lists.freedesktop.org
Subject: Re: Reviving the LPSS PWM patches
Date: Thu, 7 Apr 2016 15:19:04 +0530	[thread overview]
Message-ID: <57062D10.4070401@linux.intel.com> (raw)
In-Reply-To: <20160406105613.GB14854@vicerveza.homeunix.net>

On Wednesday 06 April 2016 04:26 PM, Lluís Batlle i Rossell wrote:
> On Tue, Apr 05, 2016 at 09:06:25PM +0200, Lluís Batlle i Rossell wrote:
>> On Tue, Apr 05, 2016 at 12:39:30PM +0200, Lluís Batlle i Rossell wrote:
>>> On Tue, Apr 05, 2016 at 12:03:44PM +0530, Kumar, Shobhit wrote:
>>>> On Thursday 31 March 2016 03:57 PM, Lluís Batlle i Rossell wrote:
>>>>> Hello,
>>>>>
>>>>> I saw that you did some work for LPSS PWM:
>>>>> https://lists.freedesktop.org/archives/intel-gfx/2016-January/085006.html
>>>
>>> Definitely I was quite blind in my initial attempts at applying the
>>> patches, and gave me the idea that they did not apply in any recent tree.
>>> I've checked that they apply and build over the released 4.5, so I will go
>>> testing that, maybe today. I will report.
>>
>> The screen goes black, as before.
>>
>> I attach the dmesg after applying the four patches (3 + 1) to 4.5.
>> PWM_LPSS=y and PWM_LPSS_PLATFORM=y
>>
>> I also attach a dmesg of a panicked kernel that actually does run in that
>> board, so you can see that it is actually a lpss-pwm case.
>
> I don't see any trace of pwm/lpss in dmesg, so it's normal that i915 fails
> to find it. I wonder if there may be a problem in the ACPI table. I have
> the DSDT and it clearly reports the:
>
> Name (_CID, "80860F09")  // _CID: Compatible ID
> Name (_DDN, "Intel(R) PWM Controller #2 - 80860F09")  // _DDN: DOS Device Name
>
> Which should be the lpss pwm. But somehow it is not loaded, so I guess it
> fails the probing.

Can we put some prints in the probe routines and see whats happening in 
the pwm-lpss-platform.c driver. There is also a PCI PWM LPSS driver - 
pwm-lpss-pci.c Can you also enable that and see if the probe for that is 
being called and successful ?

Regards
Shobhit

>
> Maybe the DSDT is broken, and I should fix and recompile a new one for the
> pwm controller to work? I don't really know how this things work, and
> whether the kernel should report anything special if it were the case of a
> broken DSDT.
>
> Regards,
> Lluḉis.
>
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