From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f50.google.com (mail-wr1-f50.google.com [209.85.221.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 570CF3043C6 for ; Fri, 14 Nov 2025 09:59:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763114391; cv=none; b=XFt/pZYnaMO4A6paO8s+PJSy7tPrgBd33noDx0JYG9OsvR+WIHfZ9NKxnUWnP5rHudpMep8EBKUiVmU6PWY17bzmJkW23rPHXe49G9q3xyxYrtYz+2QXLAqkeW4BTkbp8AbfUc3dv6bG8XaX4dzsKTdHZ1PuQLVP+KQmx78eOVs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763114391; c=relaxed/simple; bh=DHf7STu3fVuI0v0oulr9m9V/jFgWRVRL6YvEAHPEjVY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=lTLV6LNjdhal6r07oF5i8rQfSKx7KF77pbs2NtJ4/d425NXsXQh5jvX26mH7MXFmv1yqrNgWjUyfAsqX3Rb2AqHULfWIG9ocOnRNEuupETdZ3MSjqaJjICQyOrKNCxBPIUwtVidwPm1id9vNvX1U72JU+SMU9exV4EeAu0tlOaQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=RD53t3h8; arc=none smtp.client-ip=209.85.221.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="RD53t3h8" Received: by mail-wr1-f50.google.com with SMTP id ffacd0b85a97d-42b2e9ac45aso1203202f8f.0 for ; Fri, 14 Nov 2025 01:59:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1763114388; x=1763719188; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=nrQJj+UBZFNYF2dhW3PzZmg/h3v8iAh4uR7Mb9IBPf8=; b=RD53t3h885AXokyYceQkXKqhE+pJWNkvaS/jADy94wwCEpx2LjUlzVyB5VVbNIZT5v TL+rxM3ei9PxMoDbHUXL9ARlqmGDPZK759R65fh4eHB4xSxHejHc7opWKx2DNhws4R0M 3hjyJfxVsHG84tsJXn1RSkGuQT09AUtbTE4DWfyiWG/mT3RqaxBnIdIZuCjm5O4y44oj tKC3S3uYCFYauvLi3QSVhs0hLL07iDBxlon+TNYrAymQWmX/ReGErVh0dqtKiBRZYOCT NdarqRBqEmxBXWFxBI8EMJdUcYeu5SUfoiLD98qZuX3muHyUiVqyF0jHbv8gIho20N2p Q6Ew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763114388; x=1763719188; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=nrQJj+UBZFNYF2dhW3PzZmg/h3v8iAh4uR7Mb9IBPf8=; b=XI/oV8sg5TjCWHiQX9JqtpJgbkzvpiedw6aD3OtmagPww5nzkSE1HvWluf5oKLNyJu QQ3Iu3jMP7d5cNP47r65/T1J86Ynj97EbwBM/1TJ/RiqnwR70mV2+WLMyyX8Rb0t+JJe DVESl/mNu+hWiFHChtUn8FfRFPJkq/09lqz8PeBotPq/g2if3AovAGEkyFnqe60oZwBL aMV2eOvB8IRoUsMo77mqEJOHHMv1ETyTzDAg00DkiW+ojAsS5ssbWwl6aPPmQBdCappK 8HlxNa6SqnVhAz56LjqmSweoW7RSFLjt39Zvd5KRXGYCAUokwhG4D6yjB4lshhgPctTW xk/Q== X-Forwarded-Encrypted: i=1; AJvYcCVkgbMXMPSIj74A09yafz1Ix0oYkKk6/fSngqinv8LJFKIT2MmR+4siIHtTUzG8ZNTkOA1kuYUdOYoyc4c=@vger.kernel.org X-Gm-Message-State: AOJu0YxX1t3MYnGMg/iCnOlfY5aMKvucn55DnrZvMFIHG30ExeIkCDBF 6N/J7YpoyTwwwGf/LpJQB2sdCqOoIZaVocehOLfRZ4aeHwKH84FUi01M6hDoXIhVLM5WN3zz5dO ix5NmIvs= X-Gm-Gg: ASbGnctEyXRXyYuQ4N/I4HPjWAHu/vBDspZ3Li8/2TL4Ftz+lXiretrxTbKU38YuN7H 18kc+l9DEdoopDckcsWmuWrn+0bZm/GpOe7wZKeEP/bz+zzg8XeRY1isQsOpU1HdpzNdhZFGvmn CutwLmjDsmCX0jhW5xE6Vdl2JulJWPVKicSEBK+lEuQJJQZCRzwg+XJ9/JJ8FRmW12gLmC9Mfk4 7ucTUctKHwiopb39irx7MFt4txtOtuZLWRw5LUCWci5aFveLAbG6AyiyQApWdzJevEAirso3DvI VZHMqzkvT/SXTQZmCe5WJ6dUgEjucHKrf8wiirZd7MP4SLLCy+dE/tyAXk/gTkpI2emA64WOkbG pvlHL2J/vR2kxbELbpy7+FXVun5VtKVAo3OtRHLHCZTtxlwdYkPSWpDHsN6KZJwbDj6NaIFVdpS kXazaFPfYsgBMLLX/i X-Google-Smtp-Source: AGHT+IHr/RGTftbN2wZlrzbDKOZVG2oNeQkhL8m189JNVIJ0i0dp6Io7uXTllB06dYu72314ISgwTQ== X-Received: by 2002:a05:6000:2c09:b0:429:c2fb:c268 with SMTP id ffacd0b85a97d-42b5959ec5amr2193055f8f.56.1763114387741; Fri, 14 Nov 2025 01:59:47 -0800 (PST) Received: from [192.168.1.3] ([185.48.77.170]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42b53f17cbfsm8780535f8f.35.2025.11.14.01.59.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 14 Nov 2025 01:59:47 -0800 (PST) Message-ID: <67142b63-b413-4ed6-8526-b18b38667d42@linaro.org> Date: Fri, 14 Nov 2025 09:59:46 +0000 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 v4 13/13] coresight: docs: Document etm4x timestamp interval option To: Randy Dunlap Cc: coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, Suzuki K Poulose , Mike Leach , Alexander Shishkin , Jonathan Corbet , Leo Yan References: <20251112-james-cs-syncfreq-v4-0-165ba21401dc@linaro.org> <20251112-james-cs-syncfreq-v4-13-165ba21401dc@linaro.org> <0eb1a2b7-8064-4ac5-bcf8-b4898a8b5ac7@infradead.org> Content-Language: en-US From: James Clark In-Reply-To: <0eb1a2b7-8064-4ac5-bcf8-b4898a8b5ac7@infradead.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14/11/2025 5:02 am, Randy Dunlap wrote: > > > On 11/12/25 7:22 AM, James Clark wrote: >> Document how the new field is used, maximum value and the interaction >> with SYNC timestamps. >> >> Signed-off-by: James Clark >> --- >> Documentation/trace/coresight/coresight.rst | 15 +++++++++++++-- >> 1 file changed, 13 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/trace/coresight/coresight.rst b/Documentation/trace/coresight/coresight.rst >> index 806699871b80..80b5ed09d69b 100644 >> --- a/Documentation/trace/coresight/coresight.rst >> +++ b/Documentation/trace/coresight/coresight.rst >> @@ -613,8 +613,19 @@ They are also listed in the folder /sys/bus/event_source/devices/cs_etm/format/ >> - Session local version of the system wide setting: :ref:`ETM_MODE_RETURNSTACK >> ` >> * - timestamp >> - - Session local version of the system wide setting: :ref:`ETMv4_MODE_TIMESTAMP >> - ` >> + - Controls generation and interval of timestamps. >> + >> + 0 = off, 1 = maximum interval .. 15 = minimum interval. >> + >> + Values 1 - 14 use a counter that decrements every cycle to generate a >> + timestamp on underflow. The reload value for the counter is 2 raised to >> + the power of timestamp interval - 1. If the value is 1 then the reload >> + value is 1, if the value is 11 then the reload value is 1024 etc. > > value = 11: 2^11-1 = 2047 > > Maybe add some parens? > > Will do. I had them but I removed them because it was in a sentence so it made it look like a side note. I think I'll change from words to symbols: The reload value for the counter is 2 ^ (interval - 1). Thanks James