Hi Alexander,
alex.aring@xxxxxxxxx wrote on Mon, 17 Jan 2022 17:52:10 -0500:
> Hi,
>
> On Mon, 17 Jan 2022 at 06:54, Miquel Raynal <miquel.raynal@xxxxxxxxxxx> wrote:
> >
> > These periods are expressed in time units (microseconds) while 40 and 12
> > are the number of symbol durations these periods will last. We need to
> > multiply them both with phy->symbol_duration in order to get these
> > values in microseconds.
> >
> > Fixes: 8c6ad9cc5157 ("ieee802154: Add NXP MCR20A IEEE 802.15.4 transceiver driver")
> > Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
> > ---
> > drivers/net/ieee802154/mcr20a.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/ieee802154/mcr20a.c b/drivers/net/ieee802154/mcr20a.c
> > index f0eb2d3b1c4e..e2c249aef430 100644
> > --- a/drivers/net/ieee802154/mcr20a.c
> > +++ b/drivers/net/ieee802154/mcr20a.c
> > @@ -976,8 +976,8 @@ static void mcr20a_hw_setup(struct mcr20a_local *lp)
> > dev_dbg(printdev(lp), "%s\n", __func__);
> >
> > phy->symbol_duration = 16;
> > - phy->lifs_period = 40;
> > - phy->sifs_period = 12;
> > + phy->lifs_period = 40 * phy->symbol_duration;
> > + phy->sifs_period = 12 * phy->symbol_duration;
>
> I thought we do that now in register_hw(). Why does this patch exist?
The lifs and sifs period are wrong.
Fixing this silently by generalizing the calculation is simply wrong. I
feel we need to do this in order:
1- Fix the period because it is wrong.
2- Now that the period is set to a valid value and the core is able to
do the same operation and set the variables to an identical content,
we can drop these lines from the driver.
#2 being a mechanical change, doing it without #1 means that something
that appears harmless actually changes the behavior of the driver. We
generally try to avoid that, no?
Thanks,
Miquèl
