On 11/9/2024 2:22 AM, Konrad Dybcio wrote:
On 7.11.2024 8:36 AM, Krishna Kurapati wrote:
Enabling U1 and U2 power-saving states can lead to stability and
performance issues, particularly for latency-sensitive or high-
throughput applications. These low-power link states are intended
to reduce power consumption by allowing the device to enter partial
low-power modes during idle periods. However, they can sometimes
result in unexpected behavior. Over the years, some of the issues
seen are as follows:
1. In device mode of operation, when UVC is active, enabling U1/U2
is sometimes causing packets drops due to delay in entry/exit of
intermittent low power states. These packet drops are often reflected
as Missed Isochronous transfers as the controller was not able to
send the packet in that microframe interval and hence glitches are
seen on the final transmitted video output.
2. On QCS6490-Rb3Gen2 Vision kit, ADB connection is heavily unstable
when U1/U2 is enabled. Often when link enters U2, there is a re-
enumeration seen and device is unusable for many use cases.
Would be nice to enable it on there too, then ;)
Generally per-file commits are preferred to make potential reverts
easier down the road
Hi Konrad,
I agree with you. After the SoB and the "---", I added a paragraph
mentioning that if this RFC patch looks fine, I will send a series and
make this change for all SM and QCS targets.
Let me know if the above commit text makes sense. Although I don't have
all the debug details, I didn't want others in the community face the
issues we faced and hence the patch.
Regards,
Krishna,
