From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=192.198.163.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792485090; b=OZTHKBlL403CkzM5xGZKlc/B0lhAHWQ5zI4qdLnlpNNJ0vjhPgc+meOuoJh3oXQEuhGs 6KBBzAkD+vmW7Wiqlc4hZKRo9my+GvWRN6cfjvqveF+CFmessDvh4PqTTY10Oqm0OD9bB DdULQVKTbc4GYOkDo80N9cCgk1spV2mSD6Wlfif9s0Pt2zhNX2WsGUjYBAbvS5moSIYGl x4tfxrAKzolnLQ3bWUCoNvTkgQwOrjrVhcGcW46b6BhsRUFZPw0ZeIm6ibaY/z7y5Qklv hEmRcT+7v66TT4xOJmV1t3RY+iFQQGGduBlLbNwQfIK4TEL/kvtPnyDvsTdfuMYqy2w== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792485090; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To:Organization; bh=s+1oChBSSokuHupQL3Eas8zUsbYR10ns8xAR8Q/zsUk=; b=jdulvYn3n2mo36iD3z8N1SHTZt00bJV2uKSv+c9vn2FFIkPCGqdiu76ZQfY1CJajyPdI xse58p15fWJyd6tXfTlTvH5SvexC5s/dQ5Njt9TltaTXpW+AzYGxY2YYAOgr05fXu4xLS hvdvMWESXQzkvauWxFR3aE83Lev8j3t1gzJRT8K95KpLI3sLlh9jSfqCKICGE6ejEovT+ Bq88QsonTgZkUaxxEAvhWIve+Pdx5Mtml+XuI83aLZw6eVe5AFIf1vND2A2OwJ/rm4B8J m5EOlw4bIsle6PkMm9VlpdDW19Pt/Z4gkIPqOWZGR8Vksfy0k0VK1ZiYa2bndXLBoIQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=KIZtFHFU; arc=none smtp.remote-ip=192.198.163.18 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.18]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2B44360A2606; Tue, 20 Oct 2026 08:31:29 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2B44360A2606 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=KIZtFHFU DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792485090; x=1824021090; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=ZXAjazWBp88/eOGpDfVPxZYET8/clYWgR4YQVUXPHLg=; b=KIZtFHFU01o08O+Zkhx/xPUYV/iGvNbtkFoyBznZ2rcPaKQeFH1Y3w/z SjuYure56YmZ0OFIGjh+ctWy3MNpfxUHg9nes7nNgGyoJJqV5E8CAmKXi qPYsGvkSr1lU+XgO9sT9lF8InteT31oLgMvtW5f5C/J/cQxQV37Irl9eW I6dj71HcC5G42sN9YdkWQoUsOi4mWMZ0mSiM+sCyawJRi3tl45MtKJfhM MLG8AhBVFwZTA4wx6biYZQv8pe9S6T8DHjkJXSjGpahXPSmPAPRFuPDnF JYfP+obSOT6Hxi/P7LJ9dOLnVzShdScunVwZoDkregLpvm6InSxDNR77f g==; X-CSE-ConnectionGUID: IoP0EOCoRNeCcq2Nhg2MCw== X-CSE-MsgGUID: F7irHwbWQrC3ua35ZvIBxw== X-IronPort-AV: E=McAfee;i="6800,10657,11940"; a="1209387" X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="1209387" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2026 01:31:29 -0700 X-CSE-ConnectionGUID: GkX5RfzGSyakXA5bt9nYFw== X-CSE-MsgGUID: vTIs+iXPRM6JRkmHX8MA2A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,168,1787036400"; d="scan'208";a="3161125" Received: from ettammin-mobl3.ger.corp.intel.com (HELO localhost) ([10.245.244.72]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Oct 2026 01:31:26 -0700 Date: Tue, 20 Oct 2026 11:31:23 +0300 From: Andy Shevchenko To: Jiri Slaby Cc: Vinicius Pedrosa , linux-serial@vger.kernel.org, gregkh@linuxfoundation.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, ilpo.jarvinen@linux.intel.com, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sunxi@lists.linux.dev, Andre Przywara , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Enzo Adriano Subject: Re: [PATCH v2 2/4] serial: 8250_dw: Only accept a contiguous DLF readback Message-ID: References: X-Mailing-List: linux-serial@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Tue, Oct 20, 2026 at 08:11:06AM +0200, Jiri Slaby wrote: > On 19. 10. 26, 22:06, Vinicius Pedrosa wrote: ... > > - if (reg) { > > + /* > > + * DLF is a bit field starting at bit 0, so a real one reads back as > > + * 2^n - 1. Any other value means this offset is something else. > > + */ > > + if (reg && !(reg & (reg + 1))) { > > Do I understand correctly, that this equivalent to: > if (is_power_of_2(reg + 1)) > ? Yes, and since we check for reg to be "not zero", this will work the rest. -- With Best Regards, Andy Shevchenko