Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1378480 > unrolled thread

[PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs

Back to article view | Back to linux.kernel

Contents

  [PATCH v2]  pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs Keerthy <j-keerthy@ti.com> - 2016-04-14 07:10 +0200
    Re: [PATCH v2]  pinctrl: pinctrl-single: Fix  pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs Tony Lindgren <tony@atomide.com> - 2016-04-14 18:10 +0200
    Re: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry  to use __ffs than ffs Linus Walleij <linus.walleij@linaro.org> - 2016-04-15 11:30 +0200
      Re: [PATCH v2] pinctrl: pinctrl-single: Fix  pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs Tony Lindgren <tony@atomide.com> - 2016-04-15 17:30 +0200

#1378480 — [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs

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.

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

[toc] | [next] | [standalone]

#1379062 — Re: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs

* 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
> 

[toc] | [prev] | [next] | [standalone]

#1379636 — Re: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs

On Thu, Apr 14, 2016 at 6:59 AM, Keerthy <j-keerthy@ti.com> wrote:

> 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.
>
> Boot tesed on da850-evm and checked the pinctrl sysfs nodes.

Patch applied for fixes with Tony's ACK.

Should it also be tagged for stable?

Yours,
Linus Walleij

[toc] | [prev] | [next] | [standalone]

#1379919 — Re: [PATCH v2] pinctrl: pinctrl-single: Fix pcs_parse_bits_in_pinctrl_entry to use __ffs than ffs

* Linus Walleij <linus.walleij@linaro.org> [160415 02:29]:
> On Thu, Apr 14, 2016 at 6:59 AM, Keerthy <j-keerthy@ti.com> wrote:
> 
> > 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.
> >
> > Boot tesed on da850-evm and checked the pinctrl sysfs nodes.
> 
> Patch applied for fixes with Tony's ACK.
> 
> Should it also be tagged for stable?

Probably a good idea, I can see somebody pulling hair out because
of this in various product trees.

Regards,

Tony

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web