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* [PATCH RFC] pwm: keembay: Fix build failure with -Os
       [not found] <202011160303.qi5aRChY-lkp@intel.com>
@ 2020-11-16  9:08 ` Uwe Kleine-König
  2020-11-17 17:29   ` Ayyathurai, Vijayakannan
                     ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Uwe Kleine-König @ 2020-11-16  9:08 UTC (permalink / raw)
  To: Vijayakannan Ayyathurai, Thierry Reding
  Cc: kbuild-all, Linux Memory Management List, Lai, Poey Seng,
	Vineetha G. Jaya Kumaran, Andy Shevchenko, linux-kernel, kernel,
	kernel test robot

The driver used this construct:

	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)

	static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
						   u32 val, u32 offset)
	{
		u32 buff = readl(priv->base + offset);

		buff = u32_replace_bits(buff, val, mask);
		writel(buff, priv->base + offset);
	}

	...
	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
					KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));

With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
triggers:

	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-keembay.c:16:
	In function ‘field_multiplier’,
	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
	  119 |   __bad_mask();
	      |   ^~~~~~~~~~~~
	In function ‘field_multiplier’,
	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
	  119 |   __bad_mask();
	      |   ^~~~~~~~~~~~

The compiler doesn't seem to be able to notice that with field being
0x3ffffff the expression

	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
		__bad_mask();

can be optimized away.

So use __always_inline and document the problem in a comment to fix
this.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
Hello,

I'm not sure this is the right fix. Maybe the bitfield stuff can be
changed somehow to make this problem go away, too?

Best regards
Uwe

 drivers/pwm/pwm-keembay.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pwm/pwm-keembay.c b/drivers/pwm/pwm-keembay.c
index 2b6dd070daa4..cdfdef66ff8e 100644
--- a/drivers/pwm/pwm-keembay.c
+++ b/drivers/pwm/pwm-keembay.c
@@ -63,7 +63,12 @@ static int keembay_clk_enable(struct device *dev, struct clk *clk)
 	return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
 }
 
-static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
+/*
+ * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
+ * "__always_inline" this fails to compile because the compiler doesn't notice
+ * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
+ */
+static __always_inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
 					   u32 val, u32 offset)
 {
 	u32 buff = readl(priv->base + offset);
-- 
2.28.0


^ permalink raw reply related	[flat|nested] 7+ messages in thread

* RE: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-16  9:08 ` [PATCH RFC] pwm: keembay: Fix build failure with -Os Uwe Kleine-König
@ 2020-11-17 17:29   ` Ayyathurai, Vijayakannan
  2020-11-18  9:48     ` Uwe Kleine-König
  2020-11-18 10:06   ` Uwe Kleine-König
  2020-11-18 18:00   ` Thierry Reding
  2 siblings, 1 reply; 7+ messages in thread
From: Ayyathurai, Vijayakannan @ 2020-11-17 17:29 UTC (permalink / raw)
  To: Uwe Kleine-König, Thierry Reding
  Cc: kbuild-all, Linux Memory Management List, Lai, Poey Seng,
	Andy Shevchenko, linux-kernel, kernel, lkp

Hi Uwe,

> From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Sent: Monday, 16 November, 2020 5:08 PM
> Subject: [PATCH RFC] pwm: keembay: Fix build failure with -Os
> 
> The driver used this construct:
> 
> 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> 
> 	static inline void keembay_pwm_update_bits(struct keembay_pwm
> *priv, u32 mask,
> 						   u32 val, u32 offset)
> 	{
> 		u32 buff = readl(priv->base + offset);
> 
> 		buff = u32_replace_bits(buff, val, mask);
> 		writel(buff, priv->base + offset);
> 	}
> 
> 	...
> 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> 					KMB_PWM_LEADIN_OFFSET(pwm-
> >hwpwm));
> 
> With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> triggers:
> 
> 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-
> keembay.c:16:
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at
> /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at
> /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 
> The compiler doesn't seem to be able to notice that with field being
> 0x3ffffff the expression
> 
> 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> 		__bad_mask();
> 
> can be optimized away.
> 
> So use __always_inline and document the problem in a comment to fix
> this.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

Thank you for spending time in resolving this build failure.

I shall prepare and share the next version of patch with your approach.
 
> ---
> Hello,
> 
> I'm not sure this is the right fix. Maybe the bitfield stuff can be
> changed somehow to make this problem go away, too?
> 
> Best regards
> Uwe
> 
>  drivers/pwm/pwm-keembay.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pwm/pwm-keembay.c b/drivers/pwm/pwm-keembay.c
> index 2b6dd070daa4..cdfdef66ff8e 100644
> --- a/drivers/pwm/pwm-keembay.c
> +++ b/drivers/pwm/pwm-keembay.c
> @@ -63,7 +63,12 @@ static int keembay_clk_enable(struct device *dev,
> struct clk *clk)
>  	return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
>  }
> 
> -static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32
> mask,
> +/*
> + * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
> + * "__always_inline" this fails to compile because the compiler doesn't notice
> + * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
> + */
> +static __always_inline void keembay_pwm_update_bits(struct
> keembay_pwm *priv, u32 mask,
>  					   u32 val, u32 offset)
>  {
>  	u32 buff = readl(priv->base + offset);
> --
> 2.28.0

Thanks,
Vijay

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-17 17:29   ` Ayyathurai, Vijayakannan
@ 2020-11-18  9:48     ` Uwe Kleine-König
  0 siblings, 0 replies; 7+ messages in thread
From: Uwe Kleine-König @ 2020-11-18  9:48 UTC (permalink / raw)
  To: Ayyathurai, Vijayakannan
  Cc: Thierry Reding, kbuild-all, lkp, linux-kernel,
	Linux Memory Management List, kernel, Andy Shevchenko, Lai,
	Poey Seng

[-- Attachment #1: Type: text/plain, Size: 2634 bytes --]

On Tue, Nov 17, 2020 at 05:29:01PM +0000, Ayyathurai, Vijayakannan wrote:
> Hi Uwe,
> 
> > From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > Sent: Monday, 16 November, 2020 5:08 PM
> > Subject: [PATCH RFC] pwm: keembay: Fix build failure with -Os
> > 
> > The driver used this construct:
> > 
> > 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> > 
> > 	static inline void keembay_pwm_update_bits(struct keembay_pwm
> > *priv, u32 mask,
> > 						   u32 val, u32 offset)
> > 	{
> > 		u32 buff = readl(priv->base + offset);
> > 
> > 		buff = u32_replace_bits(buff, val, mask);
> > 		writel(buff, priv->base + offset);
> > 	}
> > 
> > 	...
> > 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> > 					KMB_PWM_LEADIN_OFFSET(pwm-
> > >hwpwm));
> > 
> > With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> > triggers:
> > 
> > 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-
> > keembay.c:16:
> > 	In function ‘field_multiplier’,
> > 	    inlined from ‘keembay_pwm_update_bits’ at
> > /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> > ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > 	  119 |   __bad_mask();
> > 	      |   ^~~~~~~~~~~~
> > 	In function ‘field_multiplier’,
> > 	    inlined from ‘keembay_pwm_update_bits’ at
> > /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> > ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > 	  119 |   __bad_mask();
> > 	      |   ^~~~~~~~~~~~
> > 
> > The compiler doesn't seem to be able to notice that with field being
> > 0x3ffffff the expression
> > 
> > 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> > 		__bad_mask();
> > 
> > can be optimized away.
> > 
> > So use __always_inline and document the problem in a comment to fix
> > this.
> > 
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> 
> Thank you for spending time in resolving this build failure.
> 
> I shall prepare and share the next version of patch with your approach.

I don't understand this last sentence. IMHO there is currently nothing
you have to do for this problem. You can send an Ack however if you want
to.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-16  9:08 ` [PATCH RFC] pwm: keembay: Fix build failure with -Os Uwe Kleine-König
  2020-11-17 17:29   ` Ayyathurai, Vijayakannan
@ 2020-11-18 10:06   ` Uwe Kleine-König
  2020-11-18 17:41     ` Ayyathurai, Vijayakannan
  2020-11-18 18:00   ` Thierry Reding
  2 siblings, 1 reply; 7+ messages in thread
From: Uwe Kleine-König @ 2020-11-18 10:06 UTC (permalink / raw)
  To: Vijayakannan Ayyathurai, Thierry Reding
  Cc: kbuild-all, kernel test robot, linux-kernel,
	Linux Memory Management List, Vineetha G. Jaya Kumaran, kernel,
	Andy Shevchenko, Lai, Poey Seng, linux-pwm

[-- Attachment #1: Type: text/plain, Size: 2448 bytes --]

[Cc: += linux-pwm which I forgot for the initial submission]

Hello,

On Mon, Nov 16, 2020 at 10:08:04AM +0100, Uwe Kleine-König wrote:
> The driver used this construct:
> 
> 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> 
> 	static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
> 						   u32 val, u32 offset)
> 	{
> 		u32 buff = readl(priv->base + offset);
> 
> 		buff = u32_replace_bits(buff, val, mask);
> 		writel(buff, priv->base + offset);
> 	}
> 
> 	...
> 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> 					KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
> 
> With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> triggers:
> 
> 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-keembay.c:16:
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 
> The compiler doesn't seem to be able to notice that with field being
> 0x3ffffff the expression
> 
> 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> 		__bad_mask();
> 
> can be optimized away.
> 
> So use __always_inline and document the problem in a comment to fix
> this.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
> Hello,
> 
> I'm not sure this is the right fix. Maybe the bitfield stuff can be
> changed somehow to make this problem go away, too?

Note, this patch

Fixes: cdbea243f419 ("pwm: Add PWM driver for Intel Keem Bay")

so this isn't critical for v5.10.

@thierry: If this is ok for you and Vijayakannan, you can squash this
into the original commit.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | https://www.pengutronix.de/ |

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* RE: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-18 10:06   ` Uwe Kleine-König
@ 2020-11-18 17:41     ` Ayyathurai, Vijayakannan
  2020-11-18 18:01       ` Thierry Reding
  0 siblings, 1 reply; 7+ messages in thread
From: Ayyathurai, Vijayakannan @ 2020-11-18 17:41 UTC (permalink / raw)
  To: Uwe Kleine-König, Thierry Reding
  Cc: kbuild-all, lkp, linux-kernel, Linux Memory Management List,
	kernel, Andy Shevchenko, Lai, Poey Seng, linux-pwm

Hi Thierry,

> From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> Subject: Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
> 
> [Cc: += linux-pwm which I forgot for the initial submission]
> 
> Hello,
> 
> On Mon, Nov 16, 2020 at 10:08:04AM +0100, Uwe Kleine-König wrote:
> > The driver used this construct:
> >
> > 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> >
> > 	static inline void keembay_pwm_update_bits(struct keembay_pwm
> *priv, u32 mask,
> > 						   u32 val, u32 offset)
> > 	{
> > 		u32 buff = readl(priv->base + offset);
> >
> > 		buff = u32_replace_bits(buff, val, mask);
> > 		writel(buff, priv->base + offset);
> > 	}
> >
> > 	...
> > 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> > 					KMB_PWM_LEADIN_OFFSET(pwm-
> >hwpwm));
> >
> > With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> > triggers:
> >
> > 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-
> keembay.c:16:
> > 	In function ‘field_multiplier’,
> > 	    inlined from ‘keembay_pwm_update_bits’ at
> /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > 	  119 |   __bad_mask();
> > 	      |   ^~~~~~~~~~~~
> > 	In function ‘field_multiplier’,
> > 	    inlined from ‘keembay_pwm_update_bits’ at
> /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > 	  119 |   __bad_mask();
> > 	      |   ^~~~~~~~~~~~
> >
> > The compiler doesn't seem to be able to notice that with field being
> > 0x3ffffff the expression
> >
> > 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> > 		__bad_mask();
> >
> > can be optimized away.
> >
> > So use __always_inline and document the problem in a comment to fix
> > this.
> >
> > Reported-by: kernel test robot <lkp@intel.com>
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > ---
> > Hello,
> >
> > I'm not sure this is the right fix. Maybe the bitfield stuff can be
> > changed somehow to make this problem go away, too?
> 
> Note, this patch
> 
> Fixes: cdbea243f419 ("pwm: Add PWM driver for Intel Keem Bay")
> 
> so this isn't critical for v5.10.
> 
> @thierry: If this is ok for you and Vijayakannan, you can squash this
> into the original commit.
> 

I am ok with Uwe approach.
I have compiled the change and tested in Keembay board as well.

> Best regards
> Uwe
> 
> --
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | https://www.pengutronix.de/ |

Thanks,
Vijay

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-16  9:08 ` [PATCH RFC] pwm: keembay: Fix build failure with -Os Uwe Kleine-König
  2020-11-17 17:29   ` Ayyathurai, Vijayakannan
  2020-11-18 10:06   ` Uwe Kleine-König
@ 2020-11-18 18:00   ` Thierry Reding
  2 siblings, 0 replies; 7+ messages in thread
From: Thierry Reding @ 2020-11-18 18:00 UTC (permalink / raw)
  To: Uwe Kleine-König
  Cc: Vijayakannan Ayyathurai, kbuild-all,
	Linux Memory Management List, Lai, Poey Seng,
	Vineetha G. Jaya Kumaran, Andy Shevchenko, linux-kernel, kernel,
	kernel test robot

[-- Attachment #1: Type: text/plain, Size: 2125 bytes --]

On Mon, Nov 16, 2020 at 10:08:04AM +0100, Uwe Kleine-König wrote:
> The driver used this construct:
> 
> 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> 
> 	static inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
> 						   u32 val, u32 offset)
> 	{
> 		u32 buff = readl(priv->base + offset);
> 
> 		buff = u32_replace_bits(buff, val, mask);
> 		writel(buff, priv->base + offset);
> 	}
> 
> 	...
> 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> 					KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
> 
> With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> triggers:
> 
> 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-keembay.c:16:
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 	In function ‘field_multiplier’,
> 	    inlined from ‘keembay_pwm_update_bits’ at /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to ‘__bad_mask’ declared with attribute error: bad bitfield mask
> 	  119 |   __bad_mask();
> 	      |   ^~~~~~~~~~~~
> 
> The compiler doesn't seem to be able to notice that with field being
> 0x3ffffff the expression
> 
> 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> 		__bad_mask();
> 
> can be optimized away.
> 
> So use __always_inline and document the problem in a comment to fix
> this.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
> Hello,
> 
> I'm not sure this is the right fix. Maybe the bitfield stuff can be
> changed somehow to make this problem go away, too?
> 
> Best regards
> Uwe
> 
>  drivers/pwm/pwm-keembay.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

Applied, thanks.

Thierry

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^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
  2020-11-18 17:41     ` Ayyathurai, Vijayakannan
@ 2020-11-18 18:01       ` Thierry Reding
  0 siblings, 0 replies; 7+ messages in thread
From: Thierry Reding @ 2020-11-18 18:01 UTC (permalink / raw)
  To: Ayyathurai, Vijayakannan
  Cc: Uwe Kleine-König, kbuild-all, lkp, linux-kernel,
	Linux Memory Management List, kernel, Andy Shevchenko, Lai,
	Poey Seng, linux-pwm

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On Wed, Nov 18, 2020 at 05:41:57PM +0000, Ayyathurai, Vijayakannan wrote:
> Hi Thierry,
> 
> > From: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > Subject: Re: [PATCH RFC] pwm: keembay: Fix build failure with -Os
> > 
> > [Cc: += linux-pwm which I forgot for the initial submission]
> > 
> > Hello,
> > 
> > On Mon, Nov 16, 2020 at 10:08:04AM +0100, Uwe Kleine-König wrote:
> > > The driver used this construct:
> > >
> > > 	#define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
> > >
> > > 	static inline void keembay_pwm_update_bits(struct keembay_pwm
> > *priv, u32 mask,
> > > 						   u32 val, u32 offset)
> > > 	{
> > > 		u32 buff = readl(priv->base + offset);
> > >
> > > 		buff = u32_replace_bits(buff, val, mask);
> > > 		writel(buff, priv->base + offset);
> > > 	}
> > >
> > > 	...
> > > 	keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
> > > 					KMB_PWM_LEADIN_OFFSET(pwm-
> > >hwpwm));
> > >
> > > With CONFIG_CC_OPTIMIZE_FOR_SIZE the compiler (here: gcc 10.2.0) this
> > > triggers:
> > >
> > > 	In file included from /home/uwe/gsrc/linux/drivers/pwm/pwm-
> > keembay.c:16:
> > > 	In function ‘field_multiplier’,
> > > 	    inlined from ‘keembay_pwm_update_bits’ at
> > /home/uwe/gsrc/linux/include/linux/bitfield.h:124:17:
> > > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> > ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > > 	  119 |   __bad_mask();
> > > 	      |   ^~~~~~~~~~~~
> > > 	In function ‘field_multiplier’,
> > > 	    inlined from ‘keembay_pwm_update_bits’ at
> > /home/uwe/gsrc/linux/include/linux/bitfield.h:154:1:
> > > 	/home/uwe/gsrc/linux/include/linux/bitfield.h:119:3: error: call to
> > ‘__bad_mask’ declared with attribute error: bad bitfield mask
> > > 	  119 |   __bad_mask();
> > > 	      |   ^~~~~~~~~~~~
> > >
> > > The compiler doesn't seem to be able to notice that with field being
> > > 0x3ffffff the expression
> > >
> > > 	if ((field | (field - 1)) & ((field | (field - 1)) + 1))
> > > 		__bad_mask();
> > >
> > > can be optimized away.
> > >
> > > So use __always_inline and document the problem in a comment to fix
> > > this.
> > >
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > > ---
> > > Hello,
> > >
> > > I'm not sure this is the right fix. Maybe the bitfield stuff can be
> > > changed somehow to make this problem go away, too?
> > 
> > Note, this patch
> > 
> > Fixes: cdbea243f419 ("pwm: Add PWM driver for Intel Keem Bay")
> > 
> > so this isn't critical for v5.10.
> > 
> > @thierry: If this is ok for you and Vijayakannan, you can squash this
> > into the original commit.
> > 
> 
> I am ok with Uwe approach.
> I have compiled the change and tested in Keembay board as well.

I'll take that as a Tested-by. Next time, if you go through the trouble
of testing a patch, make sure to reply with a:

Tested-by: Your Name <your@email.com>

So that patchwork can pick that up and credit you for it.

Thierry

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^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2020-11-18 18:01 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
     [not found] <202011160303.qi5aRChY-lkp@intel.com>
2020-11-16  9:08 ` [PATCH RFC] pwm: keembay: Fix build failure with -Os Uwe Kleine-König
2020-11-17 17:29   ` Ayyathurai, Vijayakannan
2020-11-18  9:48     ` Uwe Kleine-König
2020-11-18 10:06   ` Uwe Kleine-König
2020-11-18 17:41     ` Ayyathurai, Vijayakannan
2020-11-18 18:01       ` Thierry Reding
2020-11-18 18:00   ` Thierry Reding

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