From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH] TSL2550 driver bugfix Date: Wed, 01 Jul 2009 10:00:56 +0000 Message-ID: <4A4B33D8.1070903@cam.ac.uk> References: <4A4A2FBC.1060804@valueteam.com> <4A4A4036.3000408@cam.ac.uk> <4A4B1A71.20101@valueteam.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A4B1A71.20101-EZxuzQJkuwwybS5Ee8rs3A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Michele De Candia (VT)" Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, giometti-k2GhghHVRtY@public.gmane.org List-Id: linux-i2c@vger.kernel.org Looks good to me. (perhaps a bit more detail in the commit message of the patch?) Acked-by: Jonathan Cameron > Jonathan Cameron wrote: >> Michele De Candia (VT) wrote: >> >>> Hi all, >>> >>> I've tested TSL2550 driver and I've found a bug: when light is off, >>> returned value from tsl2550_calculate_lux function is -1 when it should >>> be 0 (sensor correctly read that light was off). >>> >>> I think the bug is that a zero c0 value (approximated value of ch0) is >>> misinterpreted as an error. >>> I'm attaching you a patch that fixes the bug. >>> >>> Regards, >>> Michele Jr De Candia >>> >> Sounds reasonable, but I think a stray line got away in your patch >> (see below) >> Not to mention, if the c1 <= c0 check is still valid, should you not also >> confirm that c1 == 0 as well? Perhaps reverse the ordering? >> > That's right. A new patch can be found in attachment. >> if (c1 <= c0) >> if(c0) { >> r = c1* 128 / c0; >> lux = ((c0 - c1) * ratio_lut[r]) / 256; >> } else >> lux = 0; >> else >> return -1; >> >> >> Signed-off-by: Michele Jr De Candia >> >> diff --git a/drivers/i2c/chips/tsl2550.c b/drivers/i2c/chips/tsl2550.c >> index 1a9cc13..6bad072 100644 >> --- a/drivers/i2c/chips/tsl2550.c >> +++ b/drivers/i2c/chips/tsl2550.c >> @@ -189,10 +189,16 @@ static int tsl2550_calculate_lux(u8 ch0, u8 ch1) >> u8 r = 128; >> >> /* Avoid division by 0 and count 1 cannot be greater than count 0 */ >> - if (c0 && (c1 <= c0)) >> - r = c1 * 128 / c0; >> - else >> - return -1; >> + if (c0) { >> + if (c1 <= c0) >> + r = c1 * 128 / c0; >> + else >> + return -1; >> + >> + /* Calculate LUX */ >> + lux = ((c0 - c1) * ratio_lut[r]) / 256; >> + } >> + else lux = 0; >> >> >> This last line should have been removed I think? >> /* Calculate LUX */ >> lux = ((c0 - c1) * ratio_lut[r]) / 256; >> >> --- >> Jonathan Cameron >> >> > Than