* Keerthy <j-keerthy@xxxxxx> [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@xxxxxx>
> ---
>
> 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@xxxxxxxxxxx>
> 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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