linux-kernel - [PATCH RESEND] tsl2550: fix lux1

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Date:   Fri,  2 Dec 2016 12:36:41 -0800
From:   Matt Ranostay <matt@...ostay.consulting>
To:     linux-kernel@...r.kernel.org
Cc:     Matt Ranostay <matt@...ostay.consulting>,
        Arnd Bergmann <arnd@...db.de>,
        Drew Fustini <pdp7pdp7@...il.com>
Subject: [PATCH RESEND] tsl2550: fix lux1_input error in low light

ADC channel 0 photodiode detects both infrared + visible light,
but ADC channel 1 just detects infrared. However, the latter is a bit
more sensitive in that range so complete darkness or low light causes
a error condition in which the chan0 - chan1 is negative that
results in a -EAGAIN.

This patch changes the resulting lux1_input sysfs attribute message from
"Resource temporarily unavailable" to a user-grokable lux value of 0.

Cc: Arnd Bergmann <arnd@...db.de>
Cc: Drew Fustini <pdp7pdp7@...il.com>
Signed-off-by: Matt Ranostay <matt@...ostay.consulting>
---
 drivers/misc/tsl2550.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/tsl2550.c b/drivers/misc/tsl2550.c
index 87a13374fdc0..eb5761067310 100644
--- a/drivers/misc/tsl2550.c
+++ b/drivers/misc/tsl2550.c
@@ -177,7 +177,7 @@ static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
 		} else
 			lux = 0;
 	else
-		return -EAGAIN;
+		return 0;

 	/* LUX range check */
 	return lux > TSL2550_MAX_LUX ? TSL2550_MAX_LUX : lux;
-- 
2.7.4