Re: [PATCH 1/3] spi: spi-gpio: actually delay in spidelay()

[Sascha Hauer <s.hauer@pengutronix.de>]

On Thu, Sep 26, 2024 at 07:55:35AM +0200, Ahmad Fatoum wrote:
> On 25.09.24 16:06, Sascha Hauer wrote:
> > spidelay() currently only is a no-op dummy function. Actually delay in
> > this function to avoid spi-gpio being faster than specified.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  drivers/spi/gpio_spi.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/spi/gpio_spi.c b/drivers/spi/gpio_spi.c
> > index e5664df3fe..a71b4eddab 100644
> > --- a/drivers/spi/gpio_spi.c
> > +++ b/drivers/spi/gpio_spi.c
> > @@ -48,7 +48,10 @@ static inline int getmiso(const struct spi_device *spi)
> >  	return !!gpio_get_value(priv->data->miso);
> >  }
> >  
> > -#define spidelay(nsecs) do { } while (0)
> > +static inline void spidelay(unsigned int nsecs)
> > +{
> > +	udelay(max(1U, nsecs / 1000));
> 
> Why delay 1us at least? Why not use ndelay?

I was under the assumption that we don't have ndelay(). We do have it,
will use it instead.

Sascha

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