diff mbox series

Input: ff-core - Correct magnitude setting for rumble compatibility

Message ID 20211130135039.13726-1-ckeepax@opensource.cirrus.com (mailing list archive)
State Accepted
Commit 8c374ef45416281c7172dc29ed438dfb445795f1
Headers show
Series Input: ff-core - Correct magnitude setting for rumble compatibility | expand

Commit Message

Charles Keepax Nov. 30, 2021, 1:50 p.m. UTC
When converting a rumble into a periodic effect, for compatibility,
the magnitude is effectively calculated using:

magnitude = max(strong_rubble / 3 + weak_rubble / 6, 0x7fff);

The rumble magnitudes are both u16 and the resulting magnitude is
s16. The max is presumably an attempt to limit the result of the
calculation to the maximum possible magnitude for the s16 result,
and thus should be a min.

However in the case of strong = weak = 0xffff, the result of the first
part of the calculation is 0x7fff, meaning that the min would be
redundant anyway, so simply remove the current max.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---
 drivers/input/ff-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Dmitry Torokhov Dec. 7, 2021, 7:23 a.m. UTC | #1
On Tue, Nov 30, 2021 at 01:50:39PM +0000, Charles Keepax wrote:
> When converting a rumble into a periodic effect, for compatibility,
> the magnitude is effectively calculated using:
> 
> magnitude = max(strong_rubble / 3 + weak_rubble / 6, 0x7fff);
> 
> The rumble magnitudes are both u16 and the resulting magnitude is
> s16. The max is presumably an attempt to limit the result of the
> calculation to the maximum possible magnitude for the s16 result,
> and thus should be a min.
> 
> However in the case of strong = weak = 0xffff, the result of the first
> part of the calculation is 0x7fff, meaning that the min would be
> redundant anyway, so simply remove the current max.
> 
> Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>

Applied, thank you.
diff mbox series

Patch

diff --git a/drivers/input/ff-core.c b/drivers/input/ff-core.c
index 1cf5deda06e19..fa8d1a4660142 100644
--- a/drivers/input/ff-core.c
+++ b/drivers/input/ff-core.c
@@ -67,7 +67,7 @@  static int compat_effect(struct ff_device *ff, struct ff_effect *effect)
 		effect->type = FF_PERIODIC;
 		effect->u.periodic.waveform = FF_SINE;
 		effect->u.periodic.period = 50;
-		effect->u.periodic.magnitude = max(magnitude, 0x7fff);
+		effect->u.periodic.magnitude = magnitude;
 		effect->u.periodic.offset = 0;
 		effect->u.periodic.phase = 0;
 		effect->u.periodic.envelope.attack_length = 0;