linux-kernel - Re: [PATCH V5 14/26] mmc: sdhci-uhs2: add set

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Message-ID: <f8b3feee-8372-a469-1853-45fb2738740d@intel.com>
Date:   Tue, 1 Nov 2022 19:14:00 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Victor Shih <victorshihgli@...il.com>, ulf.hansson@...aro.org
Cc:     linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
        benchuanggli@...il.com, HL.Liu@...esyslogic.com.tw,
        Greg.tu@...esyslogic.com.tw, takahiro.akashi@...aro.org,
        dlunev@...omium.org, Victor Shih <victor.shih@...esyslogic.com.tw>,
        Ben Chuang <ben.chuang@...esyslogic.com.tw>
Subject: Re: [PATCH V5 14/26] mmc: sdhci-uhs2: add set_timeout()

On 19/10/22 14:06, Victor Shih wrote:
> From: AKASHI Takahiro <takahiro.akashi@...aro.org>
> 
> This is a UHS-II version of sdhci's set_timeout() operation.
> 
> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
> ---
>  drivers/mmc/host/sdhci-uhs2.c | 85 +++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci-uhs2.h |  1 +
>  2 files changed, 86 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-uhs2.c b/drivers/mmc/host/sdhci-uhs2.c
> index 4dc3e904d7d2..2b90e5308764 100644
> --- a/drivers/mmc/host/sdhci-uhs2.c
> +++ b/drivers/mmc/host/sdhci-uhs2.c
> @@ -196,6 +196,91 @@ void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode,
>  }
>  EXPORT_SYMBOL_GPL(sdhci_uhs2_set_power);
>  
> +static u8 sdhci_calc_timeout_uhs2(struct sdhci_host *host, u8 *cmd_res,
> +				  u8 *dead_lock)
> +{
> +	u8 count;
> +	unsigned int cmd_res_timeout, dead_lock_timeout, current_timeout;
> +
> +	/*
> +	 * If the host controller provides us with an incorrect timeout
> +	 * value, just skip the check and use 0xE.  The hardware may take
> +	 * longer to time out, but that's much better than having a too-short
> +	 * timeout value.
> +	 */
> +	if (host->quirks & SDHCI_QUIRK_BROKEN_TIMEOUT_VAL) {
> +		*cmd_res = 0xE;
> +		*dead_lock = 0xE;
> +		return 0xE;
> +	}

Let's skip quirks you don't need for now.

> +
> +	/* timeout in us */
> +	cmd_res_timeout = 5 * 1000;
> +	dead_lock_timeout = 1 * 1000 * 1000;
> +
> +	/*
> +	 * Figure out needed cycles.
> +	 * We do this in steps in order to fit inside a 32 bit int.
> +	 * The first step is the minimum timeout, which will have a
> +	 * minimum resolution of 6 bits:
> +	 * (1) 2^13*1000 > 2^22,
> +	 * (2) host->timeout_clk < 2^16
> +	 *     =>
> +	 *     (1) / (2) > 2^6
> +	 */
> +	count = 0;
> +	current_timeout = (1 << 13) * 1000 / host->timeout_clk;
> +	while (current_timeout < cmd_res_timeout) {
> +		count++;
> +		current_timeout <<= 1;
> +		if (count >= 0xF)
> +			break;
> +	}
> +
> +	if (count >= 0xF) {
> +		DBG("%s: Too large timeout 0x%x requested for CMD_RES!\n",
> +		    mmc_hostname(host->mmc), count);
> +		count = 0xE;
> +	}
> +	*cmd_res = count;
> +
> +	count = 0;
> +	current_timeout = (1 << 13) * 1000 / host->timeout_clk;
> +	while (current_timeout < dead_lock_timeout) {
> +		count++;
> +		current_timeout <<= 1;
> +		if (count >= 0xF)
> +			break;
> +	}
> +
> +	if (count >= 0xF) {
> +		DBG("%s: Too large timeout 0x%x requested for DEADLOCK!\n",
> +		    mmc_hostname(host->mmc), count);
> +		count = 0xE;
> +	}
> +	*dead_lock = count;
> +
> +	return count;
> +}
> +
> +static void __sdhci_uhs2_set_timeout(struct sdhci_host *host)
> +{
> +	u8 cmd_res, dead_lock;
> +
> +	sdhci_calc_timeout_uhs2(host, &cmd_res, &dead_lock);
> +	cmd_res |= dead_lock << SDHCI_UHS2_TIMER_CTRL_DEADLOCK_SHIFT;

GENMASK() and FIELD_PREP() please

> +	sdhci_writeb(host, cmd_res, SDHCI_UHS2_TIMER_CTRL);
> +}
> +
> +void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd)
> +{
> +	__sdhci_set_timeout(host, cmd);
> +
> +	if (host->mmc->flags & MMC_UHS2_SUPPORT)

	if (sdhci_uhs2_mode(host))

> +		__sdhci_uhs2_set_timeout(host);
> +}
> +EXPORT_SYMBOL_GPL(sdhci_uhs2_set_timeout);
> +
>  /*****************************************************************************\
>   *                                                                           *
>   * MMC callbacks                                                             *
> diff --git a/drivers/mmc/host/sdhci-uhs2.h b/drivers/mmc/host/sdhci-uhs2.h
> index 3179915f7f79..5ea235b14108 100644
> --- a/drivers/mmc/host/sdhci-uhs2.h
> +++ b/drivers/mmc/host/sdhci-uhs2.h
> @@ -215,5 +215,6 @@ bool sdhci_uhs2_mode(struct sdhci_host *host);
>  void sdhci_uhs2_reset(struct sdhci_host *host, u16 mask);
>  void sdhci_uhs2_set_power(struct sdhci_host *host, unsigned char mode,
>  			  unsigned short vdd);
> +void sdhci_uhs2_set_timeout(struct sdhci_host *host, struct mmc_command *cmd);
>  
>  #endif /* __SDHCI_UHS2_H */