Re: [PATCH] [RESEND] mmc: sdhci-pci-gli: Improve Random 4K Read Performance of GL9763E

[Adrian Hunter]

On 24/06/21 6:25 am, Renius Chen wrote:
> During a sequence of random 4K read operations, the performance will be
> reduced due to spending much time on entering/exiting the low power state
> between requests. We disable the low power state negotiation of GL9763E
> during a sequence of random 4K read operations to improve the performance
> and enable it again after the operations have finished.
> 
> Signed-off-by: Renius Chen <reniuschengl@xxxxxxxxx>
> ---
>  drivers/mmc/host/sdhci-pci-gli.c | 86 ++++++++++++++++++++++++++++++++
>  1 file changed, 86 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-pci-gli.c b/drivers/mmc/host/sdhci-pci-gli.c
> index 302a7579a9b3..0105f728ccc4 100644
> --- a/drivers/mmc/host/sdhci-pci-gli.c
> +++ b/drivers/mmc/host/sdhci-pci-gli.c
> @@ -88,6 +88,9 @@
>  #define PCIE_GLI_9763E_SCR	 0x8E0
>  #define   GLI_9763E_SCR_AXI_REQ	   BIT(9)
>  
> +#define PCIE_GLI_9763E_CFG       0x8A0
> +#define   GLI_9763E_CFG_LPSN_DIS   BIT(12)
> +
>  #define PCIE_GLI_9763E_CFG2      0x8A4
>  #define   GLI_9763E_CFG2_L1DLY     GENMASK(28, 19)
>  #define   GLI_9763E_CFG2_L1DLY_MID 0x54
> @@ -691,6 +694,86 @@ static void sdhci_gl9763e_dumpregs(struct mmc_host *mmc)
>  	sdhci_dumpregs(mmc_priv(mmc));
>  }
>  
> +static void gl9763e_request(struct mmc_host *mmc, struct mmc_request *mrq)
> +{
> +	struct sdhci_host *host = mmc_priv(mmc);
> +	struct mmc_command *cmd;
> +	struct sdhci_pci_slot *slot = sdhci_priv(host);
> +	struct pci_dev *pdev = slot->chip->pdev;
> +	u32 value;
> +	static bool start_4k_r;
> +	static int  continuous_4k_r;

Please do not use static variables.  Instead define a struct for them and
set .priv_size in sdhci_pci_fixes e.g.

struct sdhci_pci_gli {
	static bool start_4k_r;
	static int  continuous_4k_r;
};

const struct sdhci_pci_fixes sdhci_gl9763e = {
	.quirks		= SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC,
	.probe_slot	= gli_probe_slot_gl9763e,
	.ops            = &sdhci_gl9763e_ops,
#ifdef CONFIG_PM_SLEEP
	.resume		= sdhci_cqhci_gli_resume,
	.suspend	= sdhci_cqhci_gli_suspend,
#endif
	.add_host       = gl9763e_add_host,
	.priv_size      = sizeof(struct sdhci_pci_gli);
};

And then you can get a pointer to it:

struct sdhci_pci_gli *sdhci_pci_gli = sdhci_pci_priv(slot);


> +
> +	cmd = (mrq->sbc && !(host->flags & SDHCI_AUTO_CMD23)) ? mrq->sbc : mrq->cmd;

mrq->cmd is always the main command, so why look at mrq->sbc?

> +
> +	if (cmd->opcode == MMC_READ_MULTIPLE_BLOCK) {
> +		if (cmd->data->blocks == 8) {
> +			continuous_4k_r++;
> +
> +			if ((!start_4k_r) && (continuous_4k_r >= 3)) {
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +				value &= ~GLI_9763E_VHS_REV;
> +				value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
> +				value |= GLI_9763E_CFG_LPSN_DIS;
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
> +
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +				value &= ~GLI_9763E_VHS_REV;
> +				value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +				start_4k_r = true;
> +			}
> +		} else {
> +			continuous_4k_r = 0;
> +
> +			if (start_4k_r) {
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +				value &= ~GLI_9763E_VHS_REV;
> +				value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
> +				value &= ~GLI_9763E_CFG_LPSN_DIS;
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
> +
> +				pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +				value &= ~GLI_9763E_VHS_REV;
> +				value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
> +				pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +				start_4k_r = false;
> +			}
> +		}
> +	} else {
> +		continuous_4k_r = 0;
> +
> +		if (start_4k_r)	{
> +			pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +			value &= ~GLI_9763E_VHS_REV;
> +			value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_W);
> +			pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +			pci_read_config_dword(pdev, PCIE_GLI_9763E_CFG, &value);
> +			value &= ~GLI_9763E_CFG_LPSN_DIS;
> +			pci_write_config_dword(pdev, PCIE_GLI_9763E_CFG, value);
> +
> +			pci_read_config_dword(pdev, PCIE_GLI_9763E_VHS, &value);
> +			value &= ~GLI_9763E_VHS_REV;
> +			value |= FIELD_PREP(GLI_9763E_VHS_REV, GLI_9763E_VHS_REV_R);
> +			pci_write_config_dword(pdev, PCIE_GLI_9763E_VHS, value);
> +
> +			start_4k_r = false;
> +		}

The code chunk above is the same as the previous and almost
the same as the one before that.  Please make a separate function

> +	}
> +
> +	sdhci_request(mmc, mrq);
> +}
> +
> +
>  static void sdhci_gl9763e_cqe_pre_enable(struct mmc_host *mmc)
>  {
>  	struct cqhci_host *cq_host = mmc->cqe_private;
> @@ -848,6 +931,9 @@ static int gli_probe_slot_gl9763e(struct sdhci_pci_slot *slot)
>  	gli_pcie_enable_msi(slot);
>  	host->mmc_host_ops.hs400_enhanced_strobe =
>  					gl9763e_hs400_enhanced_strobe;
> +
> +	host->mmc_host_ops.request = gl9763e_request;
> +
>  	gli_set_gl9763e(slot);
>  	sdhci_enable_v4_mode(host);
>  
>