| Message ID | 1460530865-29085-1-git-send-email-j-keerthy@ti.com |
|---|---|
| State | New |
| Headers | show |
* Keerthy <j-keerthy@ti.com> [160413 00:03]: > 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. Hmm that sounds like a bug to me, just one comment below. > --- a/drivers/pinctrl/pinctrl-single.c > +++ b/drivers/pinctrl/pinctrl-single.c > @@ -1323,9 +1323,9 @@ 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; Can you please also change the pcs->fshift = ffs(pcs->fmask) - 1 to use __ffs to avoid confusion? Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c index 748c047..897b89b 100644 --- a/drivers/pinctrl/pinctrl-single.c +++ b/drivers/pinctrl/pinctrl-single.c @@ -1323,9 +1323,9 @@ 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;
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> --- Boot tested on da850-evm drivers/pinctrl/pinctrl-single.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)