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([2600:8803:e7e4:500:5bfd:a817:5527:c417]) by smtp.gmail.com with ESMTPSA id 00721157ae682-7af3d1c07absm67668977b3.19.2026.04.14.06.21.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Apr 2026 06:21:01 -0700 (PDT) Message-ID: <70eb71c1-d239-4618-a12b-e64fff8e54d2@baylibre.com> Date: Tue, 14 Apr 2026 08:21:00 -0500 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] iio: dac: Fix passing uninitialized vref1_uV for no Vref1 case To: Andy Shevchenko , Ariana Lazar Cc: Jonathan Cameron , =?UTF-8?Q?Nuno_S=C3=A1?= , Andy Shevchenko , Jonathan Cameron , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, Dan Carpenter References: <20260414-mcp47feb02-fix4-v1-1-9d71badfd25e@microchip.com> Content-Language: en-US From: David Lechner In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/14/26 7:48 AM, Andy Shevchenko wrote: > On Tue, Apr 14, 2026 at 03:33:38PM +0300, Ariana Lazar wrote: >> Initialize vref1_uV variable to 0 before calling >> mcp47feb02_init_ch_scales() in mcp47feb02_probe() to avoid passing an >> uninitialized value when have_ext_vref1 is false. > > ... > >> + vref1_uV = 0; >> if (chip_features->have_ext_vref1) { > > I'm wondering what will happen if we do the below unconditionally? > >> ret = devm_regulator_get_enable_read_voltage(dev, "vref1"); > > If we have no regulator, we get a dummy one, right? What is the voltage will > be? 0? It will fail with -EINVAL because dummy regulator doesn't have a voltage specified anywhere. > >> if (ret > 0) { >> vref1_uV = ret; >> data->use_vref1 = true; >> } else { >> - vref1_uV = 0; >> dev_dbg(dev, "using internal band gap as voltage reference 1.\n"); >> dev_dbg(dev, "Vref1 is unavailable.\n"); >> } >