On 6/21/2023 4:45 PM, Mika Westerberg wrote:
> On Wed, Jun 21, 2023 at 05:37:22AM -0500, Sanjay R Mehta wrote:
>> From: Sanath S <Sanath.S@xxxxxxx>
>>
>> Since TMU is enabled by default on Intel SOCs for USB4 before Alpine
>> Ridge, explicit enabling or disabling of TMU is not required.
>>
>> However, the current implementation of enabling or disabling TMU based
>> on CLx state is inadequate as not all SOCs with CLx disabled have TMU
>> enabled by default, such as AMD Yellow Carp and Pink Sardine.
>>
>> To address this, a quirk named "QUIRK_TMU_DEFAULT_ENABLED" is
>> implemented to skip the enabling or disabling of TMU for SOCs where it
>> is already enabled by default, such as Intel SOCs prior to Alpine Ridge.
>
> If it is enabled by default "enabling" it again should not be a problem.
> Can you elaborate this more?
Although that is correct, Mika, we are facing an issue of display
flickering on Alpine Ridge and older device routers, from the second
hotplug onwards. This issue arises as the TMU is enabled and disabled
for each plug and unplug.
Upon reviewing the old code, it appears that this issue was already
addressed with the following code block:
/*
* No need to enable TMU on devices that don't support CLx since on
* these devices e.g. Alpine Ridge and earlier, the TMU mode HiFi
* bi-directional is enabled by default.
*/
if (!tb_switch_is_clx_supported(sw))
return 0;
However, it seems that this code has been removed in recent changes, as
the CLX-related code has been moved to a different file.
Canonical has also reported this issue and has tested this patch that
appears to resolve the issue..
If you agree, I will send the V2 patch which will address the comments
from Greg.
