Re: [PATCH v5 1/1] mmc: mtk-sd: reduce CIT for better performance

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

On 6/06/23 14:32, Wenbin Mei wrote:
> CQHCI_SSC1 indicates to CQE the polling period to use when using periodic
> SEND_QUEUE_STATUS(CMD13) polling.
> Since MSDC CQE uses msdc_hclk as ITCFVAL, so driver should use hclk
> frequency to get the actual time.
> The default value 0x1000 that corresponds to 150us for MediaTek SoCs, let's
> decrease it to 0x40 that corresponds to 2.35us, which can improve the
> performance of some eMMC devices.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Wenbin Mei <wenbin.mei@mediatek.com>

For cqhci:

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
> the previous patche link:
> v4: https://patchwork.kernel.org/project/linux-mediatek/patch/20230605121442.23622-1-wenbin.mei@mediatek.com/
> v3: https://patchwork.kernel.org/project/linux-mediatek/patch/20230605060107.22044-1-wenbin.mei@mediatek.com/
> v2: https://patchwork.kernel.org/project/linux-mediatek/patch/20230510015851.11830-1-wenbin.mei@mediatek.com/
> v1: https://patchwork.kernel.org/project/linux-mediatek/patch/20230419063048.10516-1-wenbin.mei@mediatek.com/
> ---
>  drivers/mmc/host/cqhci.h  |  2 ++
>  drivers/mmc/host/mtk-sd.c | 47 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
> 
> diff --git a/drivers/mmc/host/cqhci.h b/drivers/mmc/host/cqhci.h
> index ba9387ed90eb..e35c655edefc 100644
> --- a/drivers/mmc/host/cqhci.h
> +++ b/drivers/mmc/host/cqhci.h
> @@ -23,6 +23,8 @@
>  /* capabilities */
>  #define CQHCI_CAP			0x04
>  #define CQHCI_CAP_CS			0x10000000 /* Crypto Support */
> +#define CQHCI_CAP_ITCFMUL		GENMASK(15, 12)
> +#define CQHCI_ITCFMUL(x)		FIELD_GET(CQHCI_CAP_ITCFMUL, (x))
>  
>  /* configuration */
>  #define CQHCI_CFG			0x08
> diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
> index 8ce864169986..b582f19f82f2 100644
> --- a/drivers/mmc/host/mtk-sd.c
> +++ b/drivers/mmc/host/mtk-sd.c
> @@ -473,6 +473,7 @@ struct msdc_host {
>  	struct msdc_tune_para def_tune_para; /* default tune setting */
>  	struct msdc_tune_para saved_tune_para; /* tune result of CMD21/CMD19 */
>  	struct cqhci_host *cq_host;
> +	u32 cq_ssc1_time;
>  };
>  
>  static const struct mtk_mmc_compatible mt2701_compat = {
> @@ -2450,9 +2451,50 @@ static void msdc_hs400_enhanced_strobe(struct mmc_host *mmc,
>  	}
>  }
>  
> +static void msdc_cqe_cit_cal(struct msdc_host *host, u64 timer_ns)
> +{
> +	struct mmc_host *mmc = mmc_from_priv(host);
> +	struct cqhci_host *cq_host = mmc->cqe_private;
> +	u8 itcfmul;
> +	unsigned long hclk_freq;
> +	u64 value;
> +
> +	/*
> +	 * On MediaTek SoCs the MSDC controller's CQE uses msdc_hclk as ITCFVAL
> +	 * so we multiply/divide the HCLK frequency by ITCFMUL to calculate the
> +	 * Send Status Command Idle Timer (CIT) value.
> +	 */
> +	hclk_freq = clk_get_rate(host->h_clk);
> +	itcfmul = CQHCI_ITCFMUL(cqhci_readl(cq_host, CQHCI_CAP));
> +	switch (itcfmul) {
> +	case 0x0:
> +		do_div(hclk_freq, 1000);
> +		break;
> +	case 0x1:
> +		do_div(hclk_freq, 100);
> +		break;
> +	case 0x2:
> +		do_div(hclk_freq, 10);
> +		break;
> +	case 0x3:
> +		break;
> +	case 0x4:
> +		hclk_freq = hclk_freq * 10;
> +		break;
> +	default:
> +		host->cq_ssc1_time = 0x40;
> +		return;
> +	}
> +
> +	value = hclk_freq * timer_ns;
> +	do_div(value, 1000000000);
> +	host->cq_ssc1_time = value;
> +}
> +
>  static void msdc_cqe_enable(struct mmc_host *mmc)
>  {
>  	struct msdc_host *host = mmc_priv(mmc);
> +	struct cqhci_host *cq_host = mmc->cqe_private;
>  
>  	/* enable cmdq irq */
>  	writel(MSDC_INT_CMDQ, host->base + MSDC_INTEN);
> @@ -2462,6 +2504,9 @@ static void msdc_cqe_enable(struct mmc_host *mmc)
>  	msdc_set_busy_timeout(host, 20 * 1000000000ULL, 0);
>  	/* default read data timeout 1s */
>  	msdc_set_timeout(host, 1000000000ULL, 0);
> +
> +	/* Set the send status command idle timer */
> +	cqhci_writel(cq_host, host->cq_ssc1_time, CQHCI_SSC1);
>  }
>  
>  static void msdc_cqe_disable(struct mmc_host *mmc, bool recovery)
> @@ -2803,6 +2848,8 @@ static int msdc_drv_probe(struct platform_device *pdev)
>  		/* cqhci 16bit length */
>  		/* 0 size, means 65536 so we don't have to -1 here */
>  		mmc->max_seg_size = 64 * 1024;
> +		/* Reduce CIT to 0x40 that corresponds to 2.35us */
> +		msdc_cqe_cit_cal(host, 2350);
>  	}
>  
>  	ret = devm_request_irq(&pdev->dev, host->irq, msdc_irq,


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