Re: [PATCH] mmc: sdhc: Add PM QoS support for mmc driver

[Adrian Hunter <adrian.hunter@intel.com>]

On 1/11/24 04:44, Madhusudhan Sana wrote:
> Register mmc driver to CPU latency PM QoS framework to improve
> mmc device io performance.

Not sure host controller drivers should really be manipulating
cpu_latency_qos in order to squeeze a bit more I/O performance.

> 
> Signed-off-by: Madhusudhan Sana <quic_msana@quicinc.com>
> ---
>  drivers/mmc/host/sdhci.c | 47 ++++++++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci.h |  4 ++++
>  2 files changed, 51 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f4a7733a8ad2..ffcc9544a3df 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -359,6 +359,46 @@ static void sdhci_config_dma(struct sdhci_host *host)
>  	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>  }
>  
> +/*
> + * sdhci_pm_qos_init - initialize PM QoS request
> + */
> +void sdhci_pm_qos_init(struct sdhci_host *host)
> +{
> +	if (host->pm_qos_enable)
> +		return;
> +
> +	cpu_latency_qos_add_request(&host->pm_qos_req, PM_QOS_DEFAULT_VALUE);
> +
> +	if (cpu_latency_qos_request_active(&host->pm_qos_req))
> +		host->pm_qos_enable = true;
> +}
> +
> +/*
> + * sdhci_pm_qos_exit - remove request from PM QoS
> + */
> +void sdhci_pm_qos_exit(struct sdhci_host *host)
> +{
> +	if (!host->pm_qos_enable)
> +		return;
> +
> +	cpu_latency_qos_remove_request(&host->pm_qos_req);
> +	host->pm_qos_enable = false;
> +}
> +
> +/*
> + * sdhci_pm_qos_update - update PM QoS request
> + * @on - True, vote for perf PM QoS mode
> + *     - False, vote for power save mode.
> + */
> +static void sdhci_pm_qos_update(struct sdhci_host *host, bool on)
> +{
> +	if (!host->pm_qos_enable)
> +		return;
> +
> +	cpu_latency_qos_update_request(&host->pm_qos_req, on ?
> +						0 : PM_QOS_DEFAULT_VALUE);
> +}
> +
>  static void sdhci_init(struct sdhci_host *host, int soft)
>  {
>  	struct mmc_host *mmc = host->mmc;
> @@ -384,6 +424,9 @@ static void sdhci_init(struct sdhci_host *host, int soft)
>  		host->reinit_uhs = true;
>  		mmc->ops->set_ios(mmc, &mmc->ios);
>  	}
> +
> +	sdhci_pm_qos_init(host);
> +	sdhci_pm_qos_update(host, true);
>  }
>  
>  static void sdhci_reinit(struct sdhci_host *host)
> @@ -2072,6 +2115,7 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>  
>  	clk = sdhci_calc_clk(host, clock, &host->mmc->actual_clock);
>  	sdhci_enable_clk(host, clk);
> +	sdhci_pm_qos_update(host, true);
>  }
>  EXPORT_SYMBOL_GPL(sdhci_set_clock);
>  
> @@ -3811,6 +3855,7 @@ int sdhci_suspend_host(struct sdhci_host *host)
>  		sdhci_writel(host, 0, SDHCI_SIGNAL_ENABLE);
>  		free_irq(host->irq, host);
>  	}
> +	sdhci_pm_qos_update(host, false);
>  
>  	return 0;
>  }
> @@ -3873,6 +3918,7 @@ int sdhci_runtime_suspend_host(struct sdhci_host *host)
>  	spin_lock_irqsave(&host->lock, flags);
>  	host->runtime_suspended = true;
>  	spin_unlock_irqrestore(&host->lock, flags);
> +	sdhci_pm_qos_update(host, false);
>  
>  	return 0;
>  }
> @@ -4987,6 +5033,7 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>  	if (host->use_external_dma)
>  		sdhci_external_dma_release(host);
>  
> +	sdhci_pm_qos_exit(host);
>  	host->adma_table = NULL;
>  	host->align_buffer = NULL;
>  }
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index cd0e35a80542..685036ed888b 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -16,6 +16,7 @@
>  #include <linux/io.h>
>  #include <linux/leds.h>
>  #include <linux/interrupt.h>
> +#include <linux/devfreq.h>
>  
>  #include <linux/mmc/host.h>
>  
> @@ -675,6 +676,9 @@ struct sdhci_host {
>  
>  	u64			data_timeout;
>  
> +	struct pm_qos_request pm_qos_req;	/* PM QoS request handle */
> +	bool pm_qos_enable;			/* flag to check PM QoS is enable */
> +
>  	unsigned long private[] ____cacheline_aligned;
>  };
>