Re: [PATCH v2 2/3] mmc: core: Add mmc_delay_us() for microsecond precision delays

Sebastian Reichel <[email protected]> Sat, 25 Jul 2026 00:17:10 +0200

Newsgroups	org.kernel.vger.linux-mmc,org.kernel.vger.linux-devicetree,org.kernel.vger.linux-kernel
Message-ID	<amPkAhf_LiXGjzC3@venus>

Hi,

On Wed, Jul 22, 2026 at 03:57:00PM -0500, Judith Mendez wrote:
> Add mmc_delay_us() to support microsecond-granularity delays needed
> in MMC framework. It uses 25% margin consistent with  mmc_delay() for
> timing flexibility.
> 
> Signed-off-by: Judith Mendez <[email protected]>
> ---
> Changes since v1:
> - add patch 2/3
> ---

Looks like you should just use fsleep() from <linux/delay.h>.

Greetings,

-- Sebastian

>  drivers/mmc/core/core.h | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> index a028b48be1644..55e9fb3bab9f7 100644
> --- a/drivers/mmc/core/core.h
> +++ b/drivers/mmc/core/core.h
> @@ -73,6 +73,19 @@ static inline void mmc_delay(unsigned int ms)
>  		msleep(ms);
>  }
>  
> +static inline void mmc_delay_us(unsigned int us)
> +{
> +	if (us < 1000) {
> +		usleep_range(us, us + (us >> 2));
> +	} else {
> +		unsigned int rem_us = us % 1000;
> +
> +		msleep(us / 1000);
> +		if (rem_us)
> +			usleep_range(rem_us, rem_us + (rem_us >> 2));
> +	}
> +}
> +
>  void mmc_rescan(struct work_struct *work);
>  void mmc_start_host(struct mmc_host *host);
>  void __mmc_stop_host(struct mmc_host *host);
> -- 
> 2.54.0
> 
>

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