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Sun, 25 Oct 2026 03:17:10 -0700 (PDT) Received: from systembl0wer ([2a02:8308:4092:11f0::f9f]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e3ece5e4asm9068776f8f.59.2026.10.25.03.17.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 25 Oct 2026 03:17:10 -0700 (PDT) Date: Sun, 25 Oct 2026 11:17:08 +0100 From: Joshua Crofts To: David Carlier Cc: Jonathan Cameron , Ariana Lazar , David Lechner , Nuno =?UTF-8?B?U8Oh?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] iio: dac: mcp47feb02: reject out-of-range raw values Message-ID: <20261025111708.233f7fb8@systembl0wer> In-Reply-To: <20261024214423.865635-1-devnexen@gmail.com> References: <20261024214423.865635-1-devnexen@gmail.com> X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sat, 24 Oct 2026 22:44:23 +0100 David Carlier wrote: > mcp47feb02_write_raw() writes the user supplied raw value to the DAC > register without checking it against the chip resolution. The parts > are 8, 10 or 12 bit, and the bits above the resolution are not > implemented, so writing 300 to out_voltage0_raw on an 8-bit part sets > the output to code 44 instead of failing, and -1 is written as 0xffff. > > The out-of-range value is also cached in dac_data, so it is written > back on resume and stored to EEPROM by store_eeprom. > > Return -EINVAL for values outside [0, 2^resolution - 1]. > > Found by code inspection. Build tested with W=1 (=m and =y) only; > no hardware was available for runtime testing. This should go under the ---. > Fixes: bf394cc80369 ("iio: dac: adding support for Microchip MCP47FEB02") > Cc: stable@vger.kernel.org > Assisted-by: LLM This tag has been deprecated. Otherwise LGTM. Reviewed-by: Joshua Crofts -- Kind regards, Joshua Crofts