Re: fw_devlink breakage on SDM845 / a630 with DSI displays

[Caleb Connolly <caleb@connolly.tech>]

Hi all,

This issue is still occurring on -rc5, breaking display output on the
OnePlus 6, 6T and PocoPhone F1 unless fw_devlink=permissive is set.

I'm not quite sure how I should go about debugging and resolving this,
I'd greatly appreciate any ideas / recommendations as I would really
like to make sure 5.13 doesn't release with broken displays on these
devices.

Thanks,
On 20/05/2021 1:17 am, Caleb Connolly wrote:
>
>
> On 20/05/2021 1:06 am, Saravana Kannan wrote:
>> On Wed, May 19, 2021 at 3:43 PM Caleb Connolly <caleb@connolly.tech> wrote:
>>>
>>> Hi Saravana,
>>>
>>> On 19/05/2021 10:52 pm, Saravana Kannan wrote:
>>>> On Wed, May 19, 2021 at 8:36 AM Rob Clark <robdclark@gmail.com> wrote:
>>>>>
>>>>> + some more folks and msm list..
>>>>>
>>>>> I suppose I didn't hit this because CONFIG_FBDEV_EMULATION is not
>>>>> normally enabled for CrOS.. but I'm not really to familiar with
>>>>> fw_devlink
>>>>>
>>>>> BR,
>>>>> -R
>>>>>
>>>>> On Wed, May 19, 2021 at 8:26 AM Caleb Connolly <caleb@connolly.tech> wrote:
>>>>>>
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Since -rc1 I've been hit by some DRM breakage in freedreno which happens
>>>>>> when fw_devlink=on. It seems to cause some clocks (rcg) to get stuck and
>>>>>> break DSI displays, here's a full log from the OnePlus 6:
>>>>>> https://paste.ubuntu.com/p/8kPx4nFGF5/ (that is with
>>>>>> "deferred_probe_timeout") The PocoPhone F1 also seems to be affected by
>>>>>> this.
>>>>>>
>>>>>> The display will still come up after pressing the power button a few
>>>>>> times, although it will be incredibly slow.
>>>>>>
>>>>>> It's worth noting that the issue only happens with
>>>>>> CONFIG_FBDEV_EMULATION is enabled, I've previously required this to see
>>>>>> kernel logs during boot and general boot splash with postmarketOS.
>>>>>> Without it the display will be stuck on the bootloader splash until I
>>>>>> press the power button and cause it to update once UI (like Phosh) has
>>>>>> started (though this has been the case for quite some time).
>>>>>>
>>>>>> I'd appreciate any help with debugging / resolving this issue, I'm
>>>>>> afraid I haven't been able to determine much from some brief digging.
>>>>>>
>>>>
>>>> Hi Caleb,
>>>>
>>>> Is this a device that's supported upstream? If so, can you please
>>>> point me to the DTS file that corresponds to this board?
>>> The DTS can be found in
>>> arch/arm64/boot/dts/qcom/sdm845-oneplus-common.dtsi (the two devices
>>> "enchilada" and "fajita" share almost all hardware in common).
>>>>
>>>> Also, can you please change all the dev_dbg to dev_info in these
>>>> functions and give me the full boot log?
>>>> device_link_add()
>>>> device_links_check_suppliers()
>>> I've uploaded a log here: https://paste.ubuntu.com/p/8ynFgRWbYW/
>>> For reference, the same but with fw_devlink=permissive:
>>> https://paste.ubuntu.com/p/F2853CphHb/
>>>>
>>>> Can you also tell what device are not probing with fw_devlink=on that
>>>> might be probing with fw_devlink=permissive?
>>> The devices in question are ae00000.mdss, ae94000.dsi and ae01000.mdp.
>>>> You should be able to compare /<debugfs>/devices_deferred to figure that out.
>>> devices_deferred is empty for me,
>>
>> So, ae00000.mdss, ae94000.dsi and ae01000.mdp are probing for =on and
>> =permissive?
>>
>> That's interesting. So maybe fw_devlink is somehow changing the probe
>> order that's causing this? AFAIK, fw_devlink shouldn't cause changes
>> to probe order (it used to, but I've fixed them all).
> Yeah, they always successfully probe, it seems like fw_devlink is
> exposing some racy behaviour somewhere.
>
> The issue happens when initialising the display for framebuffer device
> emulation - with framebuffer emulation disabled it all mostly works as
> expected. With the caveat that there is nothing on the display until the
> device has finished booting AND the user causes a refresh by pressing
> the power button a few times.
>
> Perhaps this early framebuffer driver is causing confusion as it has
> different dependencies than the main driver?
>>
>>> however device_component contains
>>> (only) the following:
>>> oneplus6:/home/user# cat /sys/kernel/debug/device_component/ae00000.mdss
>>> master name                                            status
>>> -------------------------------------------------------------
>>> ae00000.mdss                                            bound
>>>
>>> device name                                            status
>>> -------------------------------------------------------------
>>> ae01000.mdp                                             bound
>>> ae94000.dsi                                             bound
>>> 5000000.gpu                                             bound
>>
>> Sorry, I have no context on this and how to interpret it. I kinda know
>> a little about the component framework, but not much. Is this file the
>> same for =on and =permissive?
> Apologies, I assumed it had something to do with fw_devlink. It's the
> same for both cases yeah.
>>
>> -Saravana
>>
>

--
Kind Regards,
Caleb