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([2600:8803:e7e4:500:4c09:7c6b:bc48:f2f7]) by smtp.gmail.com with ESMTPSA id 586e51a60fabf-4160cf239e0sm12546081fac.1.2026.03.02.06.54.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Mar 2026 06:54:53 -0800 (PST) Message-ID: <2e4acc5f-2079-4160-a4d3-6453b48eef03@baylibre.com> Date: Mon, 2 Mar 2026 08:54:52 -0600 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: accel: adxl380: fix FIFO watermark bit 8 always written as 0 To: Andy Shevchenko Cc: Antoniu Miclaus , Lars-Peter Clausen , Michael Hennerich , Ramona Gradinariu , Jonathan Cameron , =?UTF-8?Q?Nuno_S=C3=A1?= , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260227124305.55271-1-antoniu.miclaus@analog.com> <84fae6b8-d188-4e5c-af06-b342f3d27514@baylibre.com> Content-Language: en-US From: David Lechner In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/2/26 1:56 AM, Andy Shevchenko wrote: > On Sat, Feb 28, 2026 at 10:50:00AM -0600, David Lechner wrote: >> On 2/27/26 6:43 AM, Antoniu Miclaus wrote: > > ... > >>> + !!(fifo_samples & BIT(8)))); >> >> Technically, this works, but in terms of understanding the code I think >> fifo_samples >= BIT(8) would make more sense. >> >> fifo_samples is a count, not bit flags. > > I even would prefer to see in such a case > > fifo_samples > (BIT(8) - 1) > > that it will define the maximum that fits the HW, or plain number > > fifo_samples > 127 > Now that I looked at the dataheet, I get Jonathan's point. The reason this is here is that we are filling in a 9-bit value using 8-bit registers, so the MSB goes in a different register. So actually, it would probably make the most sense to write it as `fifo_samples >> 8`.