[PATCH v2 0/4] Consolidate DIV_ROUND_CLOSEST_ULL()

[PATCH v2 0/4] Consolidate DIV_ROUND_CLOSEST_ULL()

[Javi Merino]

The kernel has grown a number of different implementations of
DIV_ROUND_CLOSEST_ULL().  That is, a macro that does the same as
DIV_ROUND_CLOSEST() but with the first operand being an unsigned long
long.  That means that you have to do the division using do_div()
instead of using the C division operator '/'.

This series move the implementation in
drivers/gpu/drm/i915/intel_drv.h to linux/kernel.h and then removes
the other similar implementations of the same code in
drivers/clk/bcm/clk-kona.h, drivers/cpuidle/governors/menu.c and
drivers/media/dvb-frontends/cxd2820r_priv.h in favor of the one in
kernel.h

Changes since v1:
  - inlcude linux/kernel.h in drivers/gpu/drm/i915/intel_panel.c
    instead of drivers/gpu/drm/i915/intel_drv.h as Emil Velikov
    suggests
  - Avoid evaluating 'divisor' twice

Javi Merino (4):
  kernel.h: Implement DIV_ROUND_CLOSEST_ULL
  clk: bcm/kona: use DIV_ROUND_CLOSEST_ULL()
  cpuidle: menu: use DIV_ROUND_CLOSEST_ULL()
  media: cxd2820r: use DIV_ROUND_CLOSEST_ULL()

 drivers/clk/bcm/clk-kona.c                  | 28 +++++++---------------------
 drivers/clk/bcm/clk-kona.h                  |  1 -
 drivers/cpuidle/governors/menu.c            |  8 +-------
 drivers/gpu/drm/i915/intel_drv.h            |  3 ---
 drivers/gpu/drm/i915/intel_panel.c          |  1 +
 drivers/media/dvb-frontends/cxd2820r_c.c    |  2 +-
 drivers/media/dvb-frontends/cxd2820r_core.c |  6 ------
 drivers/media/dvb-frontends/cxd2820r_priv.h |  2 --
 drivers/media/dvb-frontends/cxd2820r_t.c    |  2 +-
 drivers/media/dvb-frontends/cxd2820r_t2.c   |  2 +-
 include/linux/kernel.h                      | 12 ++++++++++++
 11 files changed, 24 insertions(+), 43 deletions(-)

-- 
1.9.1

[PATCH v2 1/4] kernel.h: Implement DIV_ROUND_CLOSEST_ULL

[Javi Merino]

We have grown a number of different implementations of
DIV_ROUND_CLOSEST_ULL throughout the kernel.  Move the i915 one to
kernel.h so that it can be reused.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/gpu/drm/i915/intel_drv.h   |  3 ---
 drivers/gpu/drm/i915/intel_panel.c |  1 +
 include/linux/kernel.h             | 12 ++++++++++++
 3 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index eef79ccd0b7c..ba243db35840 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -36,9 +36,6 @@
 #include <drm/drm_dp_mst_helper.h>
 #include <drm/drm_rect.h>
 
-#define DIV_ROUND_CLOSEST_ULL(ll, d)	\
-({ unsigned long long _tmp = (ll)+(d)/2; do_div(_tmp, d); _tmp; })
-
 /**
  * _wait_for - magic (register) wait macro
  *
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index d8686ce89160..08532d4ffe0a 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -30,6 +30,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/kernel.h>
 #include <linux/moduleparam.h>
 #include "intel_drv.h"
 
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d6d630d31ef3..3a5b48e52a9e 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -103,6 +103,18 @@
 		(((__x) - ((__d) / 2)) / (__d));	\
 }							\
 )
+/*
+ * Same as above but for u64 dividends. divisor must be a 32-bit
+ * number.
+ */
+#define DIV_ROUND_CLOSEST_ULL(x, divisor)(		\
+{							\
+	typeof(divisor) __d = divisor;			\
+	unsigned long long _tmp = (x) + (__d) / 2;	\
+	do_div(_tmp, __d);				\
+	_tmp;						\
+}							\
+)
 
 /*
  * Multiplies an integer by a fraction, while avoiding unnecessary
-- 
1.9.1

[PATCH v2 2/4] clk: bcm/kona: use DIV_ROUND_CLOSEST_ULL()

[Javi Merino]

Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
implementation and use the kernel one.

Cc: Mike Turquette <mturquette@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Alex Elder <elder@linaro.org>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/clk/bcm/clk-kona.c | 28 +++++++---------------------
 drivers/clk/bcm/clk-kona.h |  1 -
 2 files changed, 7 insertions(+), 22 deletions(-)

diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
index 05abae89262e..a0ef4f75d457 100644
--- a/drivers/clk/bcm/clk-kona.c
+++ b/drivers/clk/bcm/clk-kona.c
@@ -15,6 +15,7 @@
 #include "clk-kona.h"
 
 #include <linux/delay.h>
+#include <linux/kernel.h>
 
 /*
  * "Policies" affect the frequencies of bus clocks provided by a
@@ -51,21 +52,6 @@ static inline u32 bitfield_replace(u32 reg_val, u32 shift, u32 width, u32 val)
 
 /* Divider and scaling helpers */
 
-/*
- * Implement DIV_ROUND_CLOSEST() for 64-bit dividend and both values
- * unsigned.  Note that unlike do_div(), the remainder is discarded
- * and the return value is the quotient (not the remainder).
- */
-u64 do_div_round_closest(u64 dividend, unsigned long divisor)
-{
-	u64 result;
-
-	result = dividend + ((u64)divisor >> 1);
-	(void)do_div(result, divisor);
-
-	return result;
-}
-
 /* Convert a divider into the scaled divisor value it represents. */
 static inline u64 scaled_div_value(struct bcm_clk_div *div, u32 reg_div)
 {
@@ -87,7 +73,7 @@ u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value, u32 billionths)
 	combined = (u64)div_value * BILLION + billionths;
 	combined <<= div->u.s.frac_width;
 
-	return do_div_round_closest(combined, BILLION);
+	return DIV_ROUND_CLOSEST_ULL(combined, BILLION);
 }
 
 /* The scaled minimum divisor representable by a divider */
@@ -731,7 +717,7 @@ static unsigned long clk_recalc_rate(struct ccu_data *ccu,
 		scaled_rate = scale_rate(pre_div, parent_rate);
 		scaled_rate = scale_rate(div, scaled_rate);
 		scaled_div = divider_read_scaled(ccu, pre_div);
-		scaled_parent_rate = do_div_round_closest(scaled_rate,
+		scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate,
 							scaled_div);
 	} else  {
 		scaled_parent_rate = scale_rate(div, parent_rate);
@@ -743,7 +729,7 @@ static unsigned long clk_recalc_rate(struct ccu_data *ccu,
 	 * rate.
 	 */
 	scaled_div = divider_read_scaled(ccu, div);
-	result = do_div_round_closest(scaled_parent_rate, scaled_div);
+	result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, scaled_div);
 
 	return (unsigned long)result;
 }
@@ -790,7 +776,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
 		scaled_rate = scale_rate(pre_div, parent_rate);
 		scaled_rate = scale_rate(div, scaled_rate);
 		scaled_pre_div = divider_read_scaled(ccu, pre_div);
-		scaled_parent_rate = do_div_round_closest(scaled_rate,
+		scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate,
 							scaled_pre_div);
 	} else {
 		scaled_parent_rate = scale_rate(div, parent_rate);
@@ -802,7 +788,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
 	 * the best we can do.
 	 */
 	if (!divider_is_fixed(div)) {
-		best_scaled_div = do_div_round_closest(scaled_parent_rate,
+		best_scaled_div = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate,
 							rate);
 		min_scaled_div = scaled_div_min(div);
 		max_scaled_div = scaled_div_max(div);
@@ -815,7 +801,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
 	}
 
 	/* OK, figure out the resulting rate */
-	result = do_div_round_closest(scaled_parent_rate, best_scaled_div);
+	result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, best_scaled_div);
 
 	if (scaled_div)
 		*scaled_div = best_scaled_div;
diff --git a/drivers/clk/bcm/clk-kona.h b/drivers/clk/bcm/clk-kona.h
index 2537b3072910..6849a64baf6d 100644
--- a/drivers/clk/bcm/clk-kona.h
+++ b/drivers/clk/bcm/clk-kona.h
@@ -503,7 +503,6 @@ extern struct clk_ops kona_peri_clk_ops;
 
 /* Externally visible functions */
 
-extern u64 do_div_round_closest(u64 dividend, unsigned long divisor);
 extern u64 scaled_div_max(struct bcm_clk_div *div);
 extern u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value,
 				u32 billionths);
-- 
1.9.1

[PATCH v2 3/4] cpuidle: menu: use DIV_ROUND_CLOSEST_ULL()

[Javi Merino]

Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
implementation and use the kernel one.

Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/cpuidle/governors/menu.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 40580794e23d..b8a5fa15ca24 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -190,12 +190,6 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
 
 static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
 
-/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
-static u64 div_round64(u64 dividend, u32 divisor)
-{
-	return div_u64(dividend + (divisor / 2), divisor);
-}
-
 /*
  * Try detecting repeating patterns by keeping track of the last 8
  * intervals, and checking if the standard deviation of that set
@@ -317,7 +311,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
 	 * operands are 32 bits.
 	 * Make sure to round up for half microseconds.
 	 */
-	data->predicted_us = div_round64((uint64_t)data->next_timer_us *
+	data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us *
 					 data->correction_factor[data->bucket],
 					 RESOLUTION * DECAY);
 
-- 
1.9.1

[PATCH v2 4/4] media: cxd2820r: use DIV_ROUND_CLOSEST_ULL()

[Javi Merino]

Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
implementation and use the kernel one.

Cc: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: Antti Palosaari <crope@iki.fi>
Reviewed-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 drivers/media/dvb-frontends/cxd2820r_c.c    | 2 +-
 drivers/media/dvb-frontends/cxd2820r_core.c | 6 ------
 drivers/media/dvb-frontends/cxd2820r_priv.h | 2 --
 drivers/media/dvb-frontends/cxd2820r_t.c    | 2 +-
 drivers/media/dvb-frontends/cxd2820r_t2.c   | 2 +-
 5 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/drivers/media/dvb-frontends/cxd2820r_c.c b/drivers/media/dvb-frontends/cxd2820r_c.c
index 149fdca3fb44..72b0e2db3aab 100644
--- a/drivers/media/dvb-frontends/cxd2820r_c.c
+++ b/drivers/media/dvb-frontends/cxd2820r_c.c
@@ -79,7 +79,7 @@ int cxd2820r_set_frontend_c(struct dvb_frontend *fe)
 
 	num = if_freq / 1000; /* Hz => kHz */
 	num *= 0x4000;
-	if_ctl = 0x4000 - cxd2820r_div_u64_round_closest(num, 41000);
+	if_ctl = 0x4000 - DIV_ROUND_CLOSEST_ULL(num, 41000);
 	buf[0] = (if_ctl >> 8) & 0x3f;
 	buf[1] = (if_ctl >> 0) & 0xff;
 
diff --git a/drivers/media/dvb-frontends/cxd2820r_core.c b/drivers/media/dvb-frontends/cxd2820r_core.c
index 422e84bbb008..490e090048ef 100644
--- a/drivers/media/dvb-frontends/cxd2820r_core.c
+++ b/drivers/media/dvb-frontends/cxd2820r_core.c
@@ -244,12 +244,6 @@ error:
 	return ret;
 }
 
-/* 64 bit div with round closest, like DIV_ROUND_CLOSEST but 64 bit */
-u32 cxd2820r_div_u64_round_closest(u64 dividend, u32 divisor)
-{
-	return div_u64(dividend + (divisor / 2), divisor);
-}
-
 static int cxd2820r_set_frontend(struct dvb_frontend *fe)
 {
 	struct cxd2820r_priv *priv = fe->demodulator_priv;
diff --git a/drivers/media/dvb-frontends/cxd2820r_priv.h b/drivers/media/dvb-frontends/cxd2820r_priv.h
index 7ff5f60c83e1..4b428959b16e 100644
--- a/drivers/media/dvb-frontends/cxd2820r_priv.h
+++ b/drivers/media/dvb-frontends/cxd2820r_priv.h
@@ -64,8 +64,6 @@ int cxd2820r_wr_reg_mask(struct cxd2820r_priv *priv, u32 reg, u8 val,
 int cxd2820r_wr_regs(struct cxd2820r_priv *priv, u32 reginfo, u8 *val,
 	int len);
 
-u32 cxd2820r_div_u64_round_closest(u64 dividend, u32 divisor);
-
 int cxd2820r_wr_regs(struct cxd2820r_priv *priv, u32 reginfo, u8 *val,
 	int len);
 
diff --git a/drivers/media/dvb-frontends/cxd2820r_t.c b/drivers/media/dvb-frontends/cxd2820r_t.c
index 51401d036530..008cb2ac8480 100644
--- a/drivers/media/dvb-frontends/cxd2820r_t.c
+++ b/drivers/media/dvb-frontends/cxd2820r_t.c
@@ -103,7 +103,7 @@ int cxd2820r_set_frontend_t(struct dvb_frontend *fe)
 
 	num = if_freq / 1000; /* Hz => kHz */
 	num *= 0x1000000;
-	if_ctl = cxd2820r_div_u64_round_closest(num, 41000);
+	if_ctl = DIV_ROUND_CLOSEST_ULL(num, 41000);
 	buf[0] = ((if_ctl >> 16) & 0xff);
 	buf[1] = ((if_ctl >>  8) & 0xff);
 	buf[2] = ((if_ctl >>  0) & 0xff);
diff --git a/drivers/media/dvb-frontends/cxd2820r_t2.c b/drivers/media/dvb-frontends/cxd2820r_t2.c
index 9c0c4f42175c..35fe364c7182 100644
--- a/drivers/media/dvb-frontends/cxd2820r_t2.c
+++ b/drivers/media/dvb-frontends/cxd2820r_t2.c
@@ -120,7 +120,7 @@ int cxd2820r_set_frontend_t2(struct dvb_frontend *fe)
 
 	num = if_freq / 1000; /* Hz => kHz */
 	num *= 0x1000000;
-	if_ctl = cxd2820r_div_u64_round_closest(num, 41000);
+	if_ctl = DIV_ROUND_CLOSEST_ULL(num, 41000);
 	buf[0] = ((if_ctl >> 16) & 0xff);
 	buf[1] = ((if_ctl >>  8) & 0xff);
 	buf[2] = ((if_ctl >>  0) & 0xff);
-- 
1.9.1

Re: [PATCH v2 1/4] kernel.h: Implement DIV_ROUND_CLOSEST_ULL

[Jeff Epler]

[for just patch 1/4; I didn't look as closely at the others]
Reviewed-by: Jeff Epler <jepler@unpythonic.net>

...with one half of a caveat (rounded up?): Like most or all of the
originals, and like DIV_ROUND_CLOSEST just above it in kernel.h, the new
code gives an incorrect answer if the temporary overflows at
+	unsigned long long _tmp = (x) + (__d) / 2;

As a doc improvement a remark could be added to a number of these
functions, but there's little reason for that to be part of this series.

Jeff

Re: [PATCH v2 2/4] clk: bcm/kona: use DIV_ROUND_CLOSEST_ULL()

[Alex Elder]

On 03/24/2015 09:03 AM, Javi Merino wrote:
> Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
> implementation and use the kernel one.
> 
> Cc: Mike Turquette <mturquette@linaro.org>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: Alex Elder <elder@linaro.org>

Acked-by: Alex Elder <elder@linaro.org>

> Signed-off-by: Javi Merino <javi.merino@arm.com>
> ---
>  drivers/clk/bcm/clk-kona.c | 28 +++++++---------------------
>  drivers/clk/bcm/clk-kona.h |  1 -
>  2 files changed, 7 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
> index 05abae89262e..a0ef4f75d457 100644
> --- a/drivers/clk/bcm/clk-kona.c
> +++ b/drivers/clk/bcm/clk-kona.c
> @@ -15,6 +15,7 @@
>  #include "clk-kona.h"
>  
>  #include <linux/delay.h>
> +#include <linux/kernel.h>
>  
>  /*
>   * "Policies" affect the frequencies of bus clocks provided by a
> @@ -51,21 +52,6 @@ static inline u32 bitfield_replace(u32 reg_val, u32 shift, u32 width, u32 val)
>  
>  /* Divider and scaling helpers */
>  
> -/*
> - * Implement DIV_ROUND_CLOSEST() for 64-bit dividend and both values
> - * unsigned.  Note that unlike do_div(), the remainder is discarded
> - * and the return value is the quotient (not the remainder).
> - */
> -u64 do_div_round_closest(u64 dividend, unsigned long divisor)
> -{
> -	u64 result;
> -
> -	result = dividend + ((u64)divisor >> 1);
> -	(void)do_div(result, divisor);
> -
> -	return result;
> -}
> -
>  /* Convert a divider into the scaled divisor value it represents. */
>  static inline u64 scaled_div_value(struct bcm_clk_div *div, u32 reg_div)
>  {
> @@ -87,7 +73,7 @@ u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value, u32 billionths)
>  	combined = (u64)div_value * BILLION + billionths;
>  	combined <<= div->u.s.frac_width;
>  
> -	return do_div_round_closest(combined, BILLION);
> +	return DIV_ROUND_CLOSEST_ULL(combined, BILLION);
>  }
>  
>  /* The scaled minimum divisor representable by a divider */
> @@ -731,7 +717,7 @@ static unsigned long clk_recalc_rate(struct ccu_data *ccu,
>  		scaled_rate = scale_rate(pre_div, parent_rate);
>  		scaled_rate = scale_rate(div, scaled_rate);
>  		scaled_div = divider_read_scaled(ccu, pre_div);
> -		scaled_parent_rate = do_div_round_closest(scaled_rate,
> +		scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate,
>  							scaled_div);
>  	} else  {
>  		scaled_parent_rate = scale_rate(div, parent_rate);
> @@ -743,7 +729,7 @@ static unsigned long clk_recalc_rate(struct ccu_data *ccu,
>  	 * rate.
>  	 */
>  	scaled_div = divider_read_scaled(ccu, div);
> -	result = do_div_round_closest(scaled_parent_rate, scaled_div);
> +	result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, scaled_div);
>  
>  	return (unsigned long)result;
>  }
> @@ -790,7 +776,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
>  		scaled_rate = scale_rate(pre_div, parent_rate);
>  		scaled_rate = scale_rate(div, scaled_rate);
>  		scaled_pre_div = divider_read_scaled(ccu, pre_div);
> -		scaled_parent_rate = do_div_round_closest(scaled_rate,
> +		scaled_parent_rate = DIV_ROUND_CLOSEST_ULL(scaled_rate,
>  							scaled_pre_div);
>  	} else {
>  		scaled_parent_rate = scale_rate(div, parent_rate);
> @@ -802,7 +788,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
>  	 * the best we can do.
>  	 */
>  	if (!divider_is_fixed(div)) {
> -		best_scaled_div = do_div_round_closest(scaled_parent_rate,
> +		best_scaled_div = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate,
>  							rate);
>  		min_scaled_div = scaled_div_min(div);
>  		max_scaled_div = scaled_div_max(div);
> @@ -815,7 +801,7 @@ static long round_rate(struct ccu_data *ccu, struct bcm_clk_div *div,
>  	}
>  
>  	/* OK, figure out the resulting rate */
> -	result = do_div_round_closest(scaled_parent_rate, best_scaled_div);
> +	result = DIV_ROUND_CLOSEST_ULL(scaled_parent_rate, best_scaled_div);
>  
>  	if (scaled_div)
>  		*scaled_div = best_scaled_div;
> diff --git a/drivers/clk/bcm/clk-kona.h b/drivers/clk/bcm/clk-kona.h
> index 2537b3072910..6849a64baf6d 100644
> --- a/drivers/clk/bcm/clk-kona.h
> +++ b/drivers/clk/bcm/clk-kona.h
> @@ -503,7 +503,6 @@ extern struct clk_ops kona_peri_clk_ops;
>  
>  /* Externally visible functions */
>  
> -extern u64 do_div_round_closest(u64 dividend, unsigned long divisor);
>  extern u64 scaled_div_max(struct bcm_clk_div *div);
>  extern u64 scaled_div_build(struct bcm_clk_div *div, u32 div_value,
>  				u32 billionths);
> 

Re: [PATCH v2 3/4] cpuidle: menu: use DIV_ROUND_CLOSEST_ULL()

[Rafael J. Wysocki]

On Tuesday, March 24, 2015 02:03:44 PM Javi Merino wrote:
> Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
> implementation and use the kernel one.

Can you please CC patch [1/4] to me too at least, so I can see how the new
macro is defined without digging it up from the entire firehose of messages
which is the LKML today?

> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Stephen Hemminger <shemminger@linux-foundation.org>
> Signed-off-by: Javi Merino <javi.merino@arm.com>
> ---
>  drivers/cpuidle/governors/menu.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index 40580794e23d..b8a5fa15ca24 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -190,12 +190,6 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
>  
>  static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
>  
> -/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
> -static u64 div_round64(u64 dividend, u32 divisor)
> -{
> -	return div_u64(dividend + (divisor / 2), divisor);
> -}
> -
>  /*
>   * Try detecting repeating patterns by keeping track of the last 8
>   * intervals, and checking if the standard deviation of that set
> @@ -317,7 +311,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
>  	 * operands are 32 bits.
>  	 * Make sure to round up for half microseconds.
>  	 */
> -	data->predicted_us = div_round64((uint64_t)data->next_timer_us *
> +	data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us *
>  					 data->correction_factor[data->bucket],
>  					 RESOLUTION * DECAY);
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.

Re: [PATCH v2 3/4] cpuidle: menu: use DIV_ROUND_CLOSEST_ULL()

[Rafael J. Wysocki]

On Tuesday, March 24, 2015 02:03:44 PM Javi Merino wrote:
> Now that the kernel provides DIV_ROUND_CLOSEST_ULL(), drop the internal
> implementation and use the kernel one.
> 
> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> Cc: Mel Gorman <mgorman@suse.de>
> Cc: Stephen Hemminger <shemminger@linux-foundation.org>
> Signed-off-by: Javi Merino <javi.merino@arm.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

> ---
>  drivers/cpuidle/governors/menu.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
> index 40580794e23d..b8a5fa15ca24 100644
> --- a/drivers/cpuidle/governors/menu.c
> +++ b/drivers/cpuidle/governors/menu.c
> @@ -190,12 +190,6 @@ static DEFINE_PER_CPU(struct menu_device, menu_devices);
>  
>  static void menu_update(struct cpuidle_driver *drv, struct cpuidle_device *dev);
>  
> -/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
> -static u64 div_round64(u64 dividend, u32 divisor)
> -{
> -	return div_u64(dividend + (divisor / 2), divisor);
> -}
> -
>  /*
>   * Try detecting repeating patterns by keeping track of the last 8
>   * intervals, and checking if the standard deviation of that set
> @@ -317,7 +311,7 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
>  	 * operands are 32 bits.
>  	 * Make sure to round up for half microseconds.
>  	 */
> -	data->predicted_us = div_round64((uint64_t)data->next_timer_us *
> +	data->predicted_us = DIV_ROUND_CLOSEST_ULL((uint64_t)data->next_timer_us *
>  					 data->correction_factor[data->bucket],
>  					 RESOLUTION * DECAY);
>  
> 

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.