From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 7A61A313540; Sun, 2 Aug 2026 18:25:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785695158; cv=none; b=iJtOZogVun36oeg+En8HT5gDwe5MWLRV+yUqQTJUhSJloAVHF7bbbnGaNSErv90f8PRVbuSPdzbytpLuJdVTpUxFfLwJAXvsyrjMrhnm8JiBQ7rZL5phmcZ3+a4DqSZIBB0NEPlEXtXASzQbLtEPNLNnT1XSQVMbavXN36PLsgs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785695158; c=relaxed/simple; bh=nI6hYgiZL53MWkJ6lVpWk5WJHEi/CCIiDxFGtTQ/jPA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YX/N1Yio2W4PxQvIpXyeXsMZfaD4rQvnkStCzBxgci5gPq7kzFYR3CgZnDBUOiMhKmzpBRzhK65AbOanduYVoCEHNTiwsd1cKht+ce2vfaAa2zpZUwNL8PsvmVGWiHkytP999U70PuzdSjF6cRSfshZ84cuT+wa11LPcgIX3gVk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=odnu2zPa; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="odnu2zPa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67A4E1F000E9; Sun, 2 Aug 2026 18:25:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785695157; bh=FvAvKNtFxAQpyl2sYFkjf13f9im8eEYRafZC6/one0A=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=odnu2zPapITvyfVNiRpW09j/ahlNM6xu+xIk7YcNoEAIqM4au2ycBoccuv4KZ7AIy XNunVn+RVeKeYXrvQxt0pTNPlIXmhvmv00D8Lrt1Do5dwgfEbb1LO2FTMvIiQho8VD Y7bJFhwWRbKlGY5Tdu6YQeqfkTQrFedNBtV0OJG9MdPvcIUgwK/IVRdq2eSXqyVg9o rdoevWxpZjwVpSaCG3oToc8hzgso8vhp+cWuJkG8AZEN4ozqREsEOa9JWe/j6rvupc zzi7W857uCTOeX6Ufh7wZc/dfK2L8Z05JbTxwbVqm7gFPrydtwIL25jFYNyzZbTPOU 4R9Q1ZX+y65IQ== Date: Sun, 2 Aug 2026 19:25:51 +0100 From: Jonathan Cameron To: David Lechner Cc: Cong Nguyen , Matteo Martelli , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Ariana Lazar Subject: Re: [PATCH] iio: adc: pac1921: fix wrong channel used in trigger handler read Message-ID: <20260802192551.76ab4a2b@jic23-huawei> In-Reply-To: <06f059d0-ac5f-408e-81ed-220f4cb1daf5@baylibre.com> References: <20260802071246.62046-1-congnt264@gmail.com> <06f059d0-ac5f-408e-81ed-220f4cb1daf5@baylibre.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 2 Aug 2026 10:48:26 -0500 David Lechner wrote: > On 8/2/26 2:12 AM, Cong Nguyen wrote: > > pac1921_trigger_handler() walks the enabled channels with > > iio_for_each_active_channel(), which yields the scan index (bit) of each > > active channel, while ch is a separate counter used to pack the samples > > contiguously into the scan buffer. > > > > The register to read was looked up with the packing counter instead of > > the scan index: > > > > ret = pac1921_read_res(priv, idev->channels[ch].address, &val); > > > > pac1921_channels[] is ordered by scan index, so channels[bit] is the > > channel that is actually enabled, whereas channels[ch] is merely the > > ch-th array entry. These coincide only when the enabled channels form a > > contiguous prefix (e.g. all channels enabled). With a sparse scan mask - > > for example when only the power channel (scan index 3) is enabled - the > > handler reads the wrong register (VBUS instead of VPOWER) and pushes it > > to userspace as the enabled channel's data. > > > > Index the channel array by the scan index (bit) to read the correct > > register, keeping ch only for contiguous packing into the scan buffer. > > > > Fixes: 371f778b83cd ("iio: adc: add support for pac1921") > > Cc: stable@vger.kernel.org > > Assisted-by: Claude:claude-opus-4 > > Signed-off-by: Cong Nguyen > > --- > > drivers/iio/adc/pac1921.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/iio/adc/pac1921.c b/drivers/iio/adc/pac1921.c > > index bce7185953ec..0037509503ed 100644 > > --- a/drivers/iio/adc/pac1921.c > > +++ b/drivers/iio/adc/pac1921.c > > @@ -1037,7 +1037,7 @@ static irqreturn_t pac1921_trigger_handler(int irq, void *p) > > iio_for_each_active_channel(idev, bit) { > > u16 val; > > > > - ret = pac1921_read_res(priv, idev->channels[ch].address, &val); > > + ret = pac1921_read_res(priv, idev->channels[bit].address, &val); > > if (ret) > > goto done; > > > > Looks correct. > > Reviewed-by: David Lechner +CC Ariana who is dealing with similar parts and might be able to sanity check this. FWIW looks correct to me too. Jonathan >