On 30/05/2023 13:20, Konrad Dybcio wrote:
The downstream kernel employs the concept of "keeping the bus alive" by voting for the minimum (XO/19.2MHz) rate at all times on certain (well, most) buses. This is a very important thing to have, as if we either have a lackluster/wrong DT that doesn't specify a (high enough) vote on a certain bus, we may lose access to the entire bus altogether. This is very apparent when we only start introducing interconnect support on a given platform and haven't yet introduced voting on all peripherals. The same can happen if we only have a single driver casting a vote on a certain bus and that driver exits/crashes/suspends. The keepalive vote is limited to the ACTIVE bucket, as keeping a permanent vote on the SLEEP one could prevent the platform from properly entering low power mode states. Introduce the very same concept, with a slight twist: the vendor kernel checks whether the rate is zero before setting the minimum vote, but that's rather silly, as in doing so we're at the mercy of CCF. Instead, explicitly clamp the rates to always be >= 19.2 MHz for providers with keep_alive=true. Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx> --- drivers/interconnect/qcom/icc-rpm.c | 10 ++++++++++ drivers/interconnect/qcom/icc-rpm.h | 3 +++ 2 files changed, 13 insertions(+)
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> -- With best wishes Dmitry
