[PATCH V5 1/2] ufs: core: Add CPU latency QoS support for ufs driver

[Peter Wang (王信友)]

On Wed, 2023-12-13 at 18:13 +0530, Maramaina Naresh wrote:
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>  Register ufs driver to CPU latency PM QoS framework to improve
> ufs device random io performance.
> 
> PM QoS initialization will insert new QoS request into the CPU
> latency QoS list with the maximum latency PM_QOS_DEFAULT_VALUE
> value.
> 
> UFS driver will vote for performance mode on scale up and power
> save mode for scale down.
> 
> If clock scaling feature is not enabled then voting will be based
> on clock on or off condition.
> 
> Provided sysfs interface to enable/disable PM QoS feature.
> 
> tiotest benchmark tool io performance results on sm8550 platform:
> 
> 1. Without PM QoS support
> 	Type (Speed in)    | Average of 18 iterations
> 	Random Write(IPOS) | 41065.13
> 	Random Read(IPOS)  | 37101.3
> 
> 2. With PM QoS support
> 	Type (Speed in)    | Average of 18 iterations
> 	Random Write(IPOS) | 46784.9
> 	Random Read(IPOS)  | 42943.4
> (Improvement with PM QoS = ~15%).
> 

Reviewed-by: Peter Wang <peter.wang at mediatek.com>