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Mon, 09 Jun 2025 13:37:51 -0700 (PDT) Received: from localhost ([2804:30c:4000:5900:b4c4:6073:1a92:4077]) by smtp.gmail.com with UTF8SMTPSA id a1e0cc1a2514c-87eeaf3b6b0sm246816241.16.2025.06.09.13.37.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Jun 2025 13:37:50 -0700 (PDT) Date: Mon, 9 Jun 2025 17:39:33 -0300 From: Marcelo Schmitt To: Jonathan Cameron Cc: Marcelo Schmitt , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, lars@metafoo.de, Michael.Hennerich@analog.com, dlechner@baylibre.com, nuno.sa@analog.com, andy@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linus.walleij@linaro.org, brgl@bgdev.pl Subject: Re: [PATCH v4 06/11] iio: adc: ad4170: Add support for buffered data capture Message-ID: References: <1e966af21b33b7dd969e1faa8126159c5dc501f7.1748829860.git.marcelo.schmitt@analog.com> <20250607180658.7db5271c@jic23-huawei> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250607180658.7db5271c@jic23-huawei> ... > > diff --git a/drivers/iio/adc/ad4170.c b/drivers/iio/adc/ad4170.c > > index 3d83c3ace569..86ef70acbf21 100644 > > --- a/drivers/iio/adc/ad4170.c > > +++ b/drivers/iio/adc/ad4170.c > > @@ -13,7 +13,11 @@ > > > +static bool ad4170_validate_scan_mask(struct iio_dev *indio_dev, > > + const unsigned long *scan_mask) > > +{ > > + unsigned int masklength = iio_get_masklength(indio_dev); > > If this becomes a useability issue we could probably generative appropriate > available_scan_masks entries and let the demuxer in the IIO core deal with > dropping the unwanted first channel. That might be preferable to just > failing if the channel isn't enabled. Yes, we can do that. I also think that would probably be the preferred way from the user's perspective. Though, that tinkering may result in a few more tens of lines of code, which I'm reluctant to add, given the size of this set. > > As a general rule, I think we've always used validate_scan_mask > to prevent too many channels being turned on, or incompatible sets of channels > rather than to prevent too few being enabled. > > Anyhow that would be a relaxation of constraints so can be done if it > turns out to be needed later. > Added to my list of patch ideas :) > > + > > + /* > > + * The channel sequencer cycles through the enabled channels in > > + * sequential order, from channel 0 to channel 15, bypassing disabled > > + * channels. When more than one channel is enabled, channel 0 must > > + * always be enabled. See datasheet channel_en register description at > > + * page 95. > > + */ > > + if (bitmap_weight(scan_mask, masklength) > 1) > > + return test_bit(0, scan_mask); > > + > > + return bitmap_weight(scan_mask, masklength) == 1; > > +}