On Wed, Aug 28, 2019 at 04:52:20PM +0800, Zhang Rui wrote: > On Fri, 2019-06-14 at 12:52 +0200, Daniel Lezcano wrote: > > Hi Nathan, > > > > On 13/06/2019 23:12, Nathan Huckleberry wrote: > > > Clang produces the following warning > > > > > > vers/thermal/rcar_gen3_thermal.c:147:33: warning: shifting a > > > negative > > > signed value is undefined [-Wshift-negative-value] / (ptat[0] - > > > ptat[2])) + > > > FIXPT_INT(TJ_3); ^~~~~~~~~~~~~~~ > > > drivers/thermal/rcar_gen3_thermal.c:126:29 > > > note: expanded from macro 'FIXPT_INT' #define FIXPT_INT(_x) ((_x) > > > << > > > FIXPT_SHIFT) ~~~~ ^ drivers/thermal/rcar_gen3_thermal.c:150:18: > > > warning: > > > shifting a negative signed value is undefined [-Wshift-negative- > > > value] > > > tsc->tj_t - FIXPT_INT(TJ_3)); ~~~~~~~~~~~~^~~~~~~~~~~~~~~~ > > > > > > Upon further investigating it looks like there is no real reason > > > for > > > TJ_3 to be -41. Usages subtract -41, code would be cleaner to just > > > add. > > > > All the code seems broken regarding the negative value shifting as > > the > > macros pass an integer: > > > > eg. > > tsc->coef.a2 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]), > > tsc->tj_t - FIXPT_INT(ths_tj_1)); > > > > thcode[1] is always < than thcode[0], > > > > thcode[1] - thcode[0] < 0 > > > > FIXPT_INT(thcode[1] - thcode[0]) is undefined > > > > > > Is it done on purpose FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]) ? > > > > Try developing the macro with the coef.a2 computation ... > > > > The code quality of this driver could be better, it deserves a rework > > IMHO ... > > > > I suggest to revert: > > > > 4eb39f79ef443fa566d36bd43f1f578d5c140305 > > bdc4480a669d476814061b4da6bb006f7048c8e5 > > 6a310f8f97bb8bc2e2bb9db6f49a1b8678c8d144 > > > > Rework the coefficient computation and re-introduce what was reverted > > in > > a nicer way. > > Sounds reasonable to me. > > Yoshihiro, > can you please clarify on this? Or else I will revert the above commits > first? > > Also CC Wolfram Sang, the driver author.
CCing Simon Horman who worked with Kaneko-san on these changes.
> thanks,
> rui
> >
> >
> > > Fixes: 4eb39f79ef44 ("thermal: rcar_gen3_thermal: Update value of
> > > Tj_1")
> > > Cc: clang-built-li...@googlegroups.com
> > > Link: https://github.com/ClangBuiltLinux/linux/issues/531
> > > Signed-off-by: Nathan Huckleberry <nh...@google.com>
> > > ---
> > > drivers/thermal/rcar_gen3_thermal.c | 8 ++++----
> > > 1 file changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/thermal/rcar_gen3_thermal.c
> > > b/drivers/thermal/rcar_gen3_thermal.c
> > > index a56463308694..f4b4558c08e9 100644
> > > --- a/drivers/thermal/rcar_gen3_thermal.c
> > > +++ b/drivers/thermal/rcar_gen3_thermal.c
> > > @@ -131,7 +131,7 @@ static inline void
> > > rcar_gen3_thermal_write(struct rcar_gen3_thermal_tsc *tsc,
> > > #define RCAR3_THERMAL_GRAN 500 /* mili Celsius */
> > >
> > > /* no idea where these constants come from */
> > > -#define TJ_3 -41
> > > +#define TJ_3 41
> > >
> > > static void rcar_gen3_thermal_calc_coefs(struct
> > > rcar_gen3_thermal_tsc *tsc,
> > > int *ptat, const int *thcode,
> > > @@ -144,11 +144,11 @@ static void
> > > rcar_gen3_thermal_calc_coefs(struct rcar_gen3_thermal_tsc *tsc,
> > > * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it
> > > unscaled
> > > */
> > > tsc->tj_t = (FIXPT_INT((ptat[1] - ptat[2]) * 157)
> > > - / (ptat[0] - ptat[2])) + FIXPT_INT(TJ_3);
> > > + / (ptat[0] - ptat[2])) - FIXPT_INT(TJ_3);
> > >
> > > tsc->coef.a1 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[2]),
> > > - tsc->tj_t - FIXPT_INT(TJ_3));
> > > - tsc->coef.b1 = FIXPT_INT(thcode[2]) - tsc->coef.a1 * TJ_3;
> > > + tsc->tj_t + FIXPT_INT(TJ_3));
> > > + tsc->coef.b1 = FIXPT_INT(thcode[2]) + tsc->coef.a1 * TJ_3;
> > >
> > > tsc->coef.a2 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]),
> > > tsc->tj_t - FIXPT_INT(ths_tj_1));
> > >
> >
> >
>
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