On Thursday, September 06, 2018, Guenter Roeck wrote:
> > > + u16 counter;
> > > +
> > > + if (priv->cks == CKS_4BIT) {
> > > + counter = DIV_ROUND_UP((timeout * rate), 4194304) + 1;
> >
> > two spaces ?
> >
> > Also, I am not sure how this prevents overflows. Was't the concern
> > that timeout * rate might overflow an int ?
Actually, I don't have to care about math overflows for large timeout
values because the driver sets a max timeout value.
if (priv->cks == CKS_4BIT) {
/* Assume slowest clock rate possible (CKS=0xF) */
priv->wdev.max_timeout = (4194304 * U8_MAX) / rate;
So if a user sends a timeout greater than that, the upper layer returns
'Invalid argument' before it ever gets to the driver.
I guess that technically means I don't really have to do the
if (counter > 256)
counter = 256;
either because I will never get a timeout value greater than my max.
(but, I might keep it in there anyway)
Chris
