From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-101.mailbox.org (mout-p-101.mailbox.org [80.241.56.151]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABBF630C377; Thu, 18 Sep 2025 13:42:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.151 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758202979; cv=none; b=sN1NrJXv9zRregZnnlbrglaqmBZuOrt7pD8jbmUNb6vFSSa199pQAHjc+0YpPnfd+0aDkvbM4DX/eWwcj6LFvx6tVutl3S3WaogrscxM204Lvni9DMTOHpq5eRZFAbqng5JGO/PswBD3/wRYX3xXX5i8R20lQ0vPMOU806meeZY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758202979; c=relaxed/simple; bh=GZe0sxEXk98WkzIWcVhMeCE+7L1gNGBRs4YCaaFsMZg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ffCsiJu8Wk8x1XTz+TCYJvy4MmpSnRxivAmC+33lZDupaurVEYSoWkpP8Hxq9btOoNfzGHTDR/PHImIAw6wdoJiuzwcjdz43ypecJVmow98NGyU4e9FbH6uCa7lEJlINBoKicXoafBPKiZ+n9x4e+leQcWzP6bDzHzlcRxsFSng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org; spf=pass smtp.mailfrom=mailbox.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=VFy57kr/; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b=KUIa3cke; arc=none smtp.client-ip=80.241.56.151 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=mailbox.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mailbox.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="VFy57kr/"; dkim=pass (2048-bit key) header.d=mailbox.org header.i=@mailbox.org header.b="KUIa3cke" Received: from smtp1.mailbox.org (smtp1.mailbox.org [IPv6:2001:67c:2050:b231:465::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-101.mailbox.org (Postfix) with ESMTPS id 4cSGzg5yQ1z9s2t; Thu, 18 Sep 2025 15:42:55 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1758202975; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gZ8xuaSg+Y3ak/XhVzDYdGSf9qdz/gdxWVoVCqGy8fY=; b=VFy57kr/2A5GstTpO1JvK1gKFqdohwlNfxIuGAQgBJoFc7qd/OWIaEgV5PYPVB8xXRQpQr XEbpoxnkS9p3MEApR7bxc6gAHOoM1JRaDG2/+01SoNqYREHpjnbb0pQ7GqRKE96HccSJPP 1hvRYKPYZlU6LZLM0E7C7S+4OUxlsPUeXPaqH2K2ccZn8dsBR7kdCnM5Jen9J/suuW/2bd Sc6bNFTed6w/WgwptL/b2w1HzKXqwjCXbxKWAQ/E6mscmFEKrwSifNfh20S5oUrymwGqAt Crj8wCqMG5hgnGCLzLMGkKw7IESLxp+Ke35eXm5np9YA7oMCXmS/ipCHc6W+Ug== Authentication-Results: outgoing_mbo_mout; dkim=pass header.d=mailbox.org header.s=mail20150812 header.b=KUIa3cke; spf=pass (outgoing_mbo_mout: domain of marek.vasut@mailbox.org designates 2001:67c:2050:b231:465::1 as permitted sender) smtp.mailfrom=marek.vasut@mailbox.org Message-ID: <353db156-e518-49c8-96ac-bd138ee64a01@mailbox.org> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mailbox.org; s=mail20150812; t=1758202973; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gZ8xuaSg+Y3ak/XhVzDYdGSf9qdz/gdxWVoVCqGy8fY=; b=KUIa3ckeXWsC2EMndtGsI8JVBZZTgBP6J9EFKmPQ/h1r8mfDFT4UxgoQOE48dVSWJwgqxx AXFWtIdgOdHERsb+00jZ+6dgWhC6cZuTW8m/erhtSwGhGBjowTqOCt+my9qcmaMO2tppth U+1tn+12vCDQJba5jsx80nbWLBcWvmUCTtVdwPf7QqGXwanOaTges+x/8NZaLy5ZLKLfoa Onl/vkS9eeVMWADJNPC6HdwEGPF7LhNNIQYi5TLlCjmKxtuV/nssEI0Y+jGtdOqRxZxj+4 J3uyroZAZN1bHBZ833+kZOz8/aXtijbGcNtzdRWSaX4WUK5kwcaBZ3XAPaKI2g== Date: Thu, 18 Sep 2025 15:42:52 +0200 Precedence: bulk X-Mailing-List: linux-clk@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH] clk: renesas: cpg-mssr: Read back reset registers to assure values latched To: "Lad, Prabhakar" , Marek Vasut Cc: linux-clk@vger.kernel.org, Geert Uytterhoeven , Michael Turquette , Stephen Boyd , linux-renesas-soc@vger.kernel.org References: <20250918030723.331634-1-marek.vasut+renesas@mailbox.org> Content-Language: en-US From: Marek Vasut In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-MBO-RS-META: h5d8tsnith6i63wqmopobtg47ngkp9g1 X-MBO-RS-ID: 99ac9da3a84910e1d60 X-Rspamd-Queue-Id: 4cSGzg5yQ1z9s2t On 9/18/25 1:11 PM, Lad, Prabhakar wrote: Hello Prabhakar, >> diff --git a/drivers/clk/renesas/renesas-cpg-mssr.c b/drivers/clk/renesas/renesas-cpg-mssr.c >> index 65dfaceea71f..7b52e8235984 100644 >> --- a/drivers/clk/renesas/renesas-cpg-mssr.c >> +++ b/drivers/clk/renesas/renesas-cpg-mssr.c >> @@ -688,6 +688,7 @@ static int cpg_mssr_reset(struct reset_controller_dev *rcdev, >> >> /* Reset module */ >> writel(bitmask, priv->pub.base0 + priv->reset_regs[reg]); >> + readl(priv->pub.base0 + priv->reset_regs[reg]); > Fyi on the RZ/T2H and RZ/N2H SoCs which uses the same driver we need > to read the reset register `7` times and confirm [0] (as mentioned in > the HW manual). So after reading do we want to confirm the bit is > set/clear? This is interesting, I wonder if the readback is something more common to this reset controller. Why 7 times ? Is this documented in one of the HW manuals ? Are those public and can you share a link to them , with the specific chapter or page I should read about this 7 times read requirement ?