linux-kernel - Re: [PATCH v2] mmc: sdhci-sprd: Wait until DLL locked after being configured

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Message-ID: <847b5295-ba23-107c-6fee-4e766a86ce7a@intel.com>
Date:   Mon, 27 Sep 2021 08:48:31 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Chunyan Zhang <zhang.lyra@...il.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     linux-mmc@...r.kernel.org, Baolin Wang <baolin.wang7@...il.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>,
        zhenxiong.lai@...soc.com, yuelin.tang@...soc.com,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] mmc: sdhci-sprd: Wait until DLL locked after being
 configured

On 26/09/21 12:28 pm, Chunyan Zhang wrote:
> From: Zhenxiong Lai <zhenxiong.lai@...soc.com>
> 
> According to the specification, DLL status has to be locked before using it.
> 
> Signed-off-by: Zhenxiong Lai <zhenxiong.lai@...soc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>

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

> ---
> Changes since v1:
> * Use read_poll_timeout() instead of while loop.
> ---
>  drivers/mmc/host/sdhci-sprd.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-sprd.c b/drivers/mmc/host/sdhci-sprd.c
> index 11e375579cfb..f33e9349e4e6 100644
> --- a/drivers/mmc/host/sdhci-sprd.c
> +++ b/drivers/mmc/host/sdhci-sprd.c
> @@ -8,6 +8,7 @@
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/highmem.h>
> +#include <linux/iopoll.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> @@ -39,6 +40,9 @@
>  #define  SDHCI_SPRD_BIT_POSRD_DLY_INV		BIT(21)
>  #define  SDHCI_SPRD_BIT_NEGRD_DLY_INV		BIT(29)
>  
> +#define SDHCI_SPRD_REG_32_DLL_STS0	0x210
> +#define SDHCI_SPRD_DLL_LOCKED		BIT(18)
> +
>  #define SDHCI_SPRD_REG_32_BUSY_POSI		0x250
>  #define  SDHCI_SPRD_BIT_OUTR_CLK_AUTO_EN	BIT(25)
>  #define  SDHCI_SPRD_BIT_INNR_CLK_AUTO_EN	BIT(24)
> @@ -256,6 +260,15 @@ static void sdhci_sprd_enable_phy_dll(struct sdhci_host *host)
>  	sdhci_writel(host, tmp, SDHCI_SPRD_REG_32_DLL_CFG);
>  	/* wait 1ms */
>  	usleep_range(1000, 1250);
> +
> +	if (read_poll_timeout(sdhci_readl, tmp, (tmp & SDHCI_SPRD_DLL_LOCKED),
> +		2000, USEC_PER_SEC, false, host, SDHCI_SPRD_REG_32_DLL_STS0)) {
> +		pr_err("%s: DLL locked fail!\n", mmc_hostname(host->mmc));
> +		pr_info("%s: DLL_STS0 : 0x%x, DLL_CFG : 0x%x\n",
> +			 mmc_hostname(host->mmc),
> +			 sdhci_readl(host, SDHCI_SPRD_REG_32_DLL_STS0),
> +			 sdhci_readl(host, SDHCI_SPRD_REG_32_DLL_CFG));
> +	}
>  }
>  
>  static void sdhci_sprd_set_clock(struct sdhci_host *host, unsigned int clock)
>