Re: [PATCH 2/2] usb: gadget: f_mass_storage: Optimize schedule() call

[Mattijs Korpershoek <mkorpershoek@kernel.org>]

Hi Patrice,

Thank you for the patch and sorry for the review delays.

On Mon, Aug 17, 2026 at 17:41, Patrice Chotard <patrice.chotard@foss.st.com> wrote:

> schedule was added in sleep_thread() by commit 4b6a3e860878
> ("usb: gadget: f_mass_storage: Add schedule() in sleep_thread()").
> to ensure that watchdog is still reset periodically even on platform
> that doesn't implement g_dnl_board_usb_cable_connected() and in case USB
> cable is not connected.
>
> Instead of calling schedule() for each for() loop iteration, call
> schedule() only in case g_dnl_board_usb_cable_connected() is not
> overloaded, in this particular case, g_dnl_board_usb_cable_connected()'s
> return value is -EOPNOTSUPP.
>
> Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
> ---
>  drivers/usb/gadget/f_mass_storage.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/gadget/f_mass_storage.c b/drivers/usb/gadget/f_mass_storage.c
> index 621852080e2..f467693d2cb 100644
> --- a/drivers/usb/gadget/f_mass_storage.c
> +++ b/drivers/usb/gadget/f_mass_storage.c
> @@ -651,6 +651,7 @@ static void busy_indicator(void)
>  static int sleep_thread(struct fsg_common *common)
>  {
>  	int i = 0, k = 0;
> +	int ret;
>  
>  	/* Wait until a signal arrives or we are woken up */
>  	for (;;) {
> @@ -673,13 +674,15 @@ static int sleep_thread(struct fsg_common *common)
>  				return -EPIPE;
>  
>  			/* Check cable connection */
> -			if (!g_dnl_board_usb_cable_connected())
> +			ret = g_dnl_board_usb_cable_connected();
> +			if (!ret)
>  				return -EIO;
> +			if (ret == -EOPNOTSUPP)
> +				schedule();

What happens on boards that override g_dnl_board_usb_cable_connected()
that return a positive value?

Per my understanding, schedule() will never be called, and the watchdog
will be triggered at some point, no?

>  
>  			k = 0;
>  		}
>  
> -		schedule();
>  		dm_usb_gadget_handle_interrupts(udcdev);
>  	}
>  	common->thread_wakeup_needed = 0;
>
> -- 
> 2.43.0