Messages in this thread Patch in this message | | | From | Uwe Kleine-König <> | Subject | [PATCH RFC] pwm: keembay: Fix build failure with -Os | Date | Mon, 16 Nov 2020 10:08:04 +0100 |
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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
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