Re: [PATCH V2 9/9] spi: bcm2835aux: make the polling duration limits configurable

[Stefan Wahren <stefan.wahren@xxxxxxxx>]

Hi Martin,

Am 24.03.19 um 18:50 schrieb kernel@xxxxxxxxxxxxxxxx:
> From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
>
> Under some circumstances the default 30 us polling limit is not optimal
> and may lead to long delays because we are waiting on an interrupt.
> with this patch we have the possibility to influence this policy.
>
> So make this limit (in us) configurable via a module parameters
> (but also modifyable via /sys/modules/...)
>
> Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
>
> ---
> Changelog:
>   V1 -> V2: remove the dependency on a different patchset focused on
> 	    making cs_change delay configurable
>
> ---
>  drivers/spi/spi-bcm2835aux.c | 25 ++++++++++++++-----------
>  1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
> index d2b58060b333..df065108122b 100644
> --- a/drivers/spi/spi-bcm2835aux.c
> +++ b/drivers/spi/spi-bcm2835aux.c
> @@ -37,6 +37,12 @@
>  #include <linux/spi/spi.h>
>  #include <linux/spinlock.h>
>
> +/* define polling limits */
> +unsigned int polling_limit_us = 30;
> +module_param(polling_limit_us, uint, 0664);
> +MODULE_PARM_DESC(polling_limit_us,
> +		 "time in us to run a transfer in polling mode\n");
> +
could you please document the case polling_limit_us = 0 ?