Re: [PATCH v6 2/2] Input: isa1200 - new driver for Imagis ISA1200

[Dmitry Torokhov]

Hi Svyatoslav,

On Wed, Jun 17, 2026 at 10:05:27AM +0300, Svyatoslav Ryhel wrote:
> From: Linus Walleij <linusw@xxxxxxxxxx>
> 
> The ISA1200 is a haptic feedback unit from Imagis Technology using two
> motors for haptic feedback in mobile phones. Used in many mobile devices
> c. 2012 including Samsung Galxy S Advance GT-I9070 (Janice), Samsung Beam
> GT-I8350 (Gavini), LG Optimus 4X P880 and LG Optimus Vu P895.
> 
> The exact datasheet for the ISA1200 is not available; all data was modeled
> based on available downstream kernel sources for various devices and
> fragments of information scattered across the internet.
> 
> Tested-by: Linus Walleij <linusw@xxxxxxxxxx> # GT-I9070 Janice
> Signed-off-by: Linus Walleij <linusw@xxxxxxxxxx>
> Co-developed-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>
> Signed-off-by: Svyatoslav Ryhel <clamor95@xxxxxxxxx>


Sashiko convinced me that using mutex_trylock() in the playback work
handler will result in dropping requests and that we are safe not taking
the lock there at all. Can you please try the following modification?

diff --git a/drivers/input/misc/isa1200.c b/drivers/input/misc/isa1200.c
index c61adc4b605c..fb7f68fa0a2b 100644
--- a/drivers/input/misc/isa1200.c
+++ b/drivers/input/misc/isa1200.c
@@ -253,15 +253,12 @@ static void isa1200_stop(struct isa1200 *isa)
 static void isa1200_play_work(struct work_struct *work)
 {
 	struct isa1200 *isa = container_of(work, struct isa1200, play_work);
-	struct input_dev *input = isa->input;
-
-	scoped_guard(mutex_try, &input->mutex) {
-		if (!isa->suspended) {
-			if (isa->level)
-				isa1200_start(isa);
-			else
-				isa1200_stop(isa);
-		}
+
+	if (!READ_ONCE(isa->suspended)) {
+		if (isa->level)
+			isa1200_start(isa);
+		else
+			isa1200_stop(isa);
 	}
 }
 

If this works no need to resend, I'll fold on my side.

Thanks.

-- 
Dmitry