From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A85D0185084; Wed, 3 Jul 2024 11:20:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005629; cv=none; b=daNZg8XLJyaRyKxugTs7MNr/5XeS9Di9Nir3L84VtlMOLS3UArtiVf0wUfAzGJdQrRb3FoPePKaX3K+QeEWUTlHVnDyHeoZ1f2uqFatuvcqIIoQXMb/xeorUs5x7MU0qrPlJibxx6eVUxYpYPP9+1QvfuHYUtEJ1FOQajLgNX2Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720005629; c=relaxed/simple; bh=psqAzXUUlSMXPmTCD01YeEynih1bCzOtk4+rDakCfCY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Cvkarss8JIJjqAhSCd7J89xQef8/FG9WZPDrYQVnK8NCxUAcfJMP6cD1IfULIstpYKOlP5RRNZPWkhcOy8TcuEOmCHiMlfrdv9M6VANzGxVc6YGPNEPD/jU7DLW4vHgFNjnlQgcgEuhuL98MrZYcsE80qtEPdF+SwipW6cQ6ckU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Hh5pzRKS; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Hh5pzRKS" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27700C2BD10; Wed, 3 Jul 2024 11:20:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1720005629; bh=psqAzXUUlSMXPmTCD01YeEynih1bCzOtk4+rDakCfCY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hh5pzRKS/J9wLCK4Rv4s4eKeKB7w2OJSApOvlrcwKLT8ZrbMd5QnwqcnV0vqRbP4D h8iGgF8dCM0fHasahDfDHbwRhd3/R0SFp8lQi4wUXtt9GKJuW5WRYi2IvBWqKkqG3U wv/AaSz7QybMA+ksyDPWRhI0ia103SFiCz91m4gA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marc Ferland , Stable@vger.kernel.org, Jonathan Cameron Subject: [PATCH 5.15 112/356] iio: dac: ad5592r: fix temperature channel scaling value Date: Wed, 3 Jul 2024 12:37:28 +0200 Message-ID: <20240703102917.335828113@linuxfoundation.org> X-Mailer: git-send-email 2.45.2 In-Reply-To: <20240703102913.093882413@linuxfoundation.org> References: <20240703102913.093882413@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Marc Ferland commit 279428df888319bf68f2686934897301a250bb84 upstream. The scale value for the temperature channel is (assuming Vref=2.5 and the datasheet): 376.7897513 When calculating both val and val2 for the temperature scale we use (3767897513/25) and multiply it by Vref (here I assume 2500mV) to obtain: 2500 * (3767897513/25) ==> 376789751300 Finally we divide with remainder by 10^9 to get: val = 376 val2 = 789751300 However, we return IIO_VAL_INT_PLUS_MICRO (should have been NANO) as the scale type. So when converting the raw temperature value to the 'processed' temperature value we will get (assuming raw=810, offset=-753): processed = (raw + offset) * scale_val = (810 + -753) * 376 = 21432 processed += div((raw + offset) * scale_val2, 10^6) += div((810 + -753) * 789751300, 10^6) += 45015 ==> 66447 ==> 66.4 Celcius instead of the expected 21.5 Celsius. Fix this issue by changing IIO_VAL_INT_PLUS_MICRO to IIO_VAL_INT_PLUS_NANO. Fixes: 56ca9db862bf ("iio: dac: Add support for the AD5592R/AD5593R ADCs/DACs") Signed-off-by: Marc Ferland Link: https://lore.kernel.org/r/20240501150554.1871390-1-marc.ferland@sonatest.com Cc: Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/dac/ad5592r-base.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/iio/dac/ad5592r-base.c +++ b/drivers/iio/dac/ad5592r-base.c @@ -411,7 +411,7 @@ static int ad5592r_read_raw(struct iio_d s64 tmp = *val * (3767897513LL / 25LL); *val = div_s64_rem(tmp, 1000000000LL, val2); - return IIO_VAL_INT_PLUS_MICRO; + return IIO_VAL_INT_PLUS_NANO; } mutex_lock(&st->lock);