[U-Boot] [PATCH u-boot-spi 1/1] spi: mvebu_a3700_spi: Fix clock prescale computation

[Marek Behún]

:) probably yes

On Wed, 17 Jul 2019 18:21:35 +0200
Stefan Roese <sr at denx.de> wrote:

> On 17.07.19 16:58, Marek Behún wrote:
> > The prescaler value computation can yield wrong result if given
> > 0x1f at the beginning: the value is computed to be 0x20, but the
> > maximum value the register can hold 0x1f, so the actual stored
> > value in this case is 0, which is obviously wrong. The first
> > condition should also take care of the 0x1f value.  
> 
> Wouldn't it be better to max the value after the calculation (see
> below)...
>   
> > Signed-off-by: Marek Behún <marek.behun at nic.cz>
> > ---
> >   drivers/spi/mvebu_a3700_spi.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/spi/mvebu_a3700_spi.c
> > b/drivers/spi/mvebu_a3700_spi.c index feeafdceaa..cc73ff3fee 100644
> > --- a/drivers/spi/mvebu_a3700_spi.c
> > +++ b/drivers/spi/mvebu_a3700_spi.c
> > @@ -181,7 +181,7 @@ static int mvebu_spi_set_speed(struct udevice
> > *bus, uint hz) data = readl(&reg->cfg);
> >   
> >   	prescale = DIV_ROUND_UP(clk_get_rate(&plat->clk), hz);
> > -	if (prescale > 0x1f)
> > +	if (prescale >= 0x1f)
> >   		prescale = 0x1f;
> >   	else if (prescale > 0xf)
> >   		prescale = 0x10 + (prescale + 1) / 2;  
> 
> Something like this:
> 
> 	if (prescale > 0xf)
>    		prescale = 0x10 + (prescale + 1) / 2;
> 	prescale = min(prescale, 0x1f);
> 
> ?
> 
> Thanks,
> Stefan