On Thu, 06 Jul 2023, Jocelyn Falempe <jfalempe@xxxxxxxxxx> wrote:
> On 04/07/2023 18:45, Jocelyn Falempe wrote:
>> On 04/07/2023 16:54, Jani Nikula wrote:
>>> On Fri, 23 Jun 2023, Jocelyn Falempe <jfalempe@xxxxxxxxxx> wrote:
>>>> Since commit fae7d186403e ("drm/probe-helper: Default to 640x480 if no
>>>> EDID on DP")
>>>> The default resolution is now 640x480 when no monitor is connected.
>>>> But Aspeed graphics is mostly used in servers, where no monitor
>>>> is attached. This also affects the "remote" resolution to 640x480,
>>>> which is
>>>> inconvenient, and breaks the anaconda installer.
>>>> So when no EDID is present, set 1024x768 as preferred resolution.
>>>
>>> This conflates "monitor connected" and "EDID present", which are not
>>> necessarily the same thing.
>>>
>>> The fallback in drm_helper_probe_single_connector_modes() is for no
>>> modes, but connector status is connected or unknown.
>>
>> When debugging the issue, I found it surprising that the status is
>> "connected" when nothing is plugged in the DP port.
>>>
>>> You could add a connector ->detect callback that returns disconnected
>>> when there's no display, and the problem should go away. If there's no
>>> ->detect callback, it'll default to connected.
>>
>> ok, I'll try that. I don't know how the hardware detect something is
>> connected, but looking at the dp code, maybe checking
>> "AST_IO_CRTC_PORT,0xDC, ASTDP_LINK_SUCCESS" would be good enough.
>
> I've tested this approach, and it works.
\o/
> But on the server I'm testing,
> there are VGA and DP output. I think on a server that has only one DP
> output, if no monitor is connected, then no modes will be reported to
> userspace, and the remote BMC may not work ?
I couldn't say, but having the driver lie about the connected status to
make it work feels wrong.
> Also I don't have physical access to the server, so I only tested when
> no monitor is plugged.
>
> I will send shortly a v2 with this change, so others can help me test
> this case.
Thanks,
Jani.
>
> Best regards,
--
Jani Nikula, Intel Open Source Graphics Center
