From: Joshua Crofts <joshua.crofts1@gmail.com>
To: "Tuna Kılıç" <tuna@tunakilic.com>
Cc: "Jonathan Cameron" <jic23@kernel.org>,
"David Lechner" <dlechner@baylibre.com>,
"Nuno Sá" <nuno.sa@analog.com>,
"Andy Shevchenko" <andy@kernel.org>,
linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iio: dac: mcp47a1: Allow full-scale output
Date: Fri, 4 Sep 2026 14:38:48 +0200 [thread overview]
Message-ID: <20260904143848.00000d7d@gmail.com> (raw)
In-Reply-To: <20260904122513.175298-1-tuna@tunakilic.com>
Hi Tuna,
Thanks for the patch!
On Fri, 4 Sep 2026 12:25:17 +0000 (UTC)
Tuna Kılıç <tuna@tunakilic.com> wrote:
> The MCP47A1 has 64 resistors but exposes 65 wiper positions. The valid
> DAC codes are 0 through 64, and code 64 selects VREF.
>
> The driver currently advertises 0 through 63 and uses 64 as the length
> argument to in_range(), which also rejects 64. Therefore userspace
> cannot select full-scale output.
>
> Advertise code 64 and make validation cover all 65 codes. Keep 64 as
> the scale denominator because the output voltage is VREF multiplied by
> the code and divided by 64.
>
> Fixes: 350d1fb9204b ("iio: dac: mcp47a1: add support for new device")
> Signed-off-by: Tuna Kılıç <tuna@tunakilic.com>
> ---
This makes sense, I must've misread the datasheet...
Can I ask how this was found? Manual code analysis or AI?
--
Kind regards,
Joshua Crofts
next prev parent reply other threads:[~2026-09-04 12:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-04 12:25 [PATCH] iio: dac: mcp47a1: Allow full-scale output Tuna Kılıç
2026-09-04 12:38 ` Joshua Crofts [this message]
2026-09-04 12:51 ` Tuna Kılıç
2026-09-06 3:54 ` Jonathan Cameron
2026-09-06 9:08 ` Tuna Kılıç
2026-09-06 17:59 ` Jonathan Cameron
2026-09-06 19:44 ` Joshua Crofts
2026-09-06 21:49 ` Jonathan Cameron
[not found] ` <1788525776688344002.1788525776@tunakilic.com>
2026-09-04 13:03 ` Joshua Crofts
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