pwm: rockchip: simplify rockchip_pwm_get_state()
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Message ID 20190919091728.24756-1-linux@rasmusvillemoes.dk
State New
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Series
  • pwm: rockchip: simplify rockchip_pwm_get_state()
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Commit Message

Rasmus Villemoes Sept. 19, 2019, 9:17 a.m. UTC
The way state->enabled is computed is rather convoluted and hard to
read - both branches of the if() actually do the exact same thing. So
remove the if(), and further simplify "<boolean condition> ? true :
false" to "<boolean condition>".

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
I stumbled on this while trying to understand how the pwm subsystem
works. This patch is a semantic no-op, but it's also possible that,
say, the first branch simply contains a "double negative" so either
the != should be == or the "false : true" should be "true : false".

 drivers/pwm/pwm-rockchip.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

Comments

Uwe Kleine-K├Ânig Sept. 19, 2019, 11:11 a.m. UTC | #1
On Thu, Sep 19, 2019 at 11:17:27AM +0200, Rasmus Villemoes wrote:
> The way state->enabled is computed is rather convoluted and hard to
> read - both branches of the if() actually do the exact same thing. So
> remove the if(), and further simplify "<boolean condition> ? true :
> false" to "<boolean condition>".
> 
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> I stumbled on this while trying to understand how the pwm subsystem
> works. This patch is a semantic no-op, but it's also possible that,
> say, the first branch simply contains a "double negative" so either
> the != should be == or the "false : true" should be "true : false".

The change looks obviously right, it's a noop.

I share your doubts however. The construct was introduced in commit 
831b2790507b ("pwm: rockchip: Use same PWM ops for each IP") by David
Wu.

Before there were rockchip_pwm_get_state_v1 for the supports_polarity =
false case and rockchip_pwm_get_state_v2 for supports_polarity = true.

In both state->enabled was assigned true if ((val & enable_conf) ==
enable_conf). So I assume everything is fine.

A confirmation by David would be great though.

As a side note: Is there publicly available documentation for this IP?
If a link were added to the driver's header we could check easily
ourselves.

Best regards
Uwe

Patch
diff mbox series

diff --git a/drivers/pwm/pwm-rockchip.c b/drivers/pwm/pwm-rockchip.c
index 51b96cb7dd25..54c6399e3f00 100644
--- a/drivers/pwm/pwm-rockchip.c
+++ b/drivers/pwm/pwm-rockchip.c
@@ -83,12 +83,7 @@  static void rockchip_pwm_get_state(struct pwm_chip *chip,
 	state->duty_cycle =  DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
 
 	val = readl_relaxed(pc->base + pc->data->regs.ctrl);
-	if (pc->data->supports_polarity)
-		state->enabled = ((val & enable_conf) != enable_conf) ?
-				 false : true;
-	else
-		state->enabled = ((val & enable_conf) == enable_conf) ?
-				 true : false;
+	state->enabled = ((val & enable_conf) == enable_conf);
 
 	if (pc->data->supports_polarity) {
 		if (!(val & PWM_DUTY_POSITIVE))