Re: [Patch v1 3/5] drm/amdkfd: Introduce debugfs option to disable baco

From: "Bhardwaj, Rajneesh" <rajneesh.bhardwaj@amd.com>
To: Alex Deucher <alexdeucher@gmail.com>
Cc: "Deucher, Alexander" <Alexander.Deucher@amd.com>,
	"Kuehling, Felix" <Felix.Kuehling@amd.com>,
	amd-gfx list <amd-gfx@lists.freedesktop.org>
Subject: Re: [Patch v1 3/5] drm/amdkfd: Introduce debugfs option to disable baco
Date: Thu, 30 Jan 2020 14:05:21 -0500	[thread overview]
Message-ID: <01c4cef2-dd70-b556-18ce-de9fc16ffd7b@amd.com> (raw)
In-Reply-To: <CADnq5_N+cMAWFyi0GdUer0AkU2LNSjrnb7i9Z4O07CR5V04FaQ@mail.gmail.com>

Hi Alex

Thanks for your time and feedback!

On 1/28/2020 3:22 PM, Alex Deucher wrote:
> [CAUTION: External Email]
>
> On Mon, Jan 27, 2020 at 8:30 PM Rajneesh Bhardwaj
> <rajneesh.bhardwaj@amd.com> wrote:
>> When BACO is enabled by default, sometimes it can cause additional
>> trouble to debug KFD issues. This debugfs override allows to temporarily
>> disable BACO for debug purpose without having to reboot the machine.
>>
>> However, in some cases one suspend-resume cycle might be needed if
>> the device is already runtime suspended.
>>
>> e.g
>>
>> sudo rtcwake -m < mem or freeze > -s 15
>>
>> or
>>
>> by triggering autosuspend event from user space, by doing something
>> like:
>>
>> echo 6000 > /sys/bus/pci/devices/0000\:03\:00.0/power/autosuspend_delay_ms
>>
>>      Usage:
>>
>> echo 0 > /sys/kernel/debug/kfd/enable_baco and run
>> cat /sys/kernel/debug/kfd/baco_status to verify whether BACO is
>> enabled or disabled by kfd driver.
>>
>> It should be noted that while enabling baco again via kfd override, we
>> must do the following steps:
>>
>> 1. echo 0 > /sys/kernel/debug/kfd/enable_baco
>> 2. sudo rtcwake -m < mem > -s 15
>>
>> In this case, we need GPU to be fully reset which is done by BIOS. This
>> is not possible in case of S2idle i.e. freeze so we must use mem for
>> sleep.
>>
> I think we can drop this patch in favor of just using the standard
> runtime pm control.  E.g.,
> /sys/class/drm/card0/device/power/control

Sure, i was using the /sys/bus/pci way to do it and found it was not 
easy. Since this sysfs exists, will drop the patch.

Regards

Rajneesh

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