Messages in this thread | | | Date | Thu, 14 Apr 2016 09:02:30 -0700 | From | Tony Lindgren <> | Subject | Re: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs |
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* Keerthy <j-keerthy@ti.com> [160413 22:00]: > pcs_parse_bits_in_pinctrl_entry uses ffs which gives bit indices > ranging from 1 to MAX. This leads to a corner case where we try to request > the pin number = MAX and fails. > > bit_pos value is being calculted using ffs. pin_num_from_lsb uses > bit_pos value. pins array is populated with: > > pin + pin_num_from_lsb. > > The above is 1 more than usual bit indices as bit_pos uses ffs to compute > first set bit. Hence the last of the pins array is populated with the MAX > value and not MAX - 1 which causes error when we call pin_request. > > mask_pos is rightly calculated as ((pcs->fmask) << (bit_pos - 1)) > Consequently val_pos and submask are correct. > > Hence use __ffs which gives (ffs(x) - 1) as the first bit set. > > fixes: 4e7e8017a8 ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules") > Signed-off-by: Keerthy <j-keerthy@ti.com> > --- > > Changes in v2: > > * Changed pcs->fshift to use __ffs instead of ffs to be consistent.
Thanks for updating it, looks good to me and still works here:
Acked-by: Tony Lindgren <tony@atomide.com>
> Boot tesed on da850-evm and checked the pinctrl sysfs nodes. > > drivers/pinctrl/pinctrl-single.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c > index fb126d5..cf9bafa 100644 > --- a/drivers/pinctrl/pinctrl-single.c > +++ b/drivers/pinctrl/pinctrl-single.c > @@ -1280,9 +1280,9 @@ static int pcs_parse_bits_in_pinctrl_entry(struct pcs_device *pcs, > > /* Parse pins in each row from LSB */ > while (mask) { > - bit_pos = ffs(mask); > + bit_pos = __ffs(mask); > pin_num_from_lsb = bit_pos / pcs->bits_per_pin; > - mask_pos = ((pcs->fmask) << (bit_pos - 1)); > + mask_pos = ((pcs->fmask) << bit_pos); > val_pos = val & mask_pos; > submask = mask & mask_pos; > > @@ -1852,7 +1852,7 @@ static int pcs_probe(struct platform_device *pdev) > ret = of_property_read_u32(np, "pinctrl-single,function-mask", > &pcs->fmask); > if (!ret) { > - pcs->fshift = ffs(pcs->fmask) - 1; > + pcs->fshift = __ffs(pcs->fmask); > pcs->fmax = pcs->fmask >> pcs->fshift; > } else { > /* If mask property doesn't exist, function mux is invalid. */ > -- > 1.9.1 >
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