From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.18]) (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 C83BB331A7E; Wed, 28 Jan 2026 10:53:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769597594; cv=none; b=l+PfvE7f0BzOsuES+3vU+DDG6kW+qKJXhGXyoKVeFSaS8VcJBmfpzraSlXd3z6gOuG2LyfQBvko7WiK/Ajp/CBCMUkld7trsjER7UctuN5+eAf27RfvmvSn6GV5ngyjgmR11d8CcYj948jBKawrgmrFU1tFL22CH9+4ZI1Xy69Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769597594; c=relaxed/simple; bh=/FkjHkx1esFcrGWS2v6HOpdOvnS0GlFCAc7PMUMlCBs=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version:Content-Type; b=I8IoI2rGr334p5h084ZDRPpnBajrgF19YJlrtywrmdAW7w/p1TH006QsUgLKiUMDpFLovSPsM2TcwEKIC10soVLhW1IS0+XM5ZtkBwbRr1mF/b+ubeomV7PpFQXe7dr/KjHpafaqKTUNZOb7cN1gs5hssDdMKR0RPCvhGDO/tbE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=NobReLzo; arc=none smtp.client-ip=198.175.65.18 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) header.d=intel.com header.i=@intel.com header.b="NobReLzo" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1769597593; x=1801133593; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=/FkjHkx1esFcrGWS2v6HOpdOvnS0GlFCAc7PMUMlCBs=; b=NobReLzofwxF6VaQcAC3SPhGdxsxlfOZ+yUCcprXX52X4oHrxjc5wVyi UiL7fWAHNFz7MbzR9uP1DkL1MNmXYKOrDq4JwZSKUqW5+hP5W1hrMRc/z rSFuu8efYGjnv80hY1E4fsiv5SrOoKcRyBVkLfsrufqfyHF0ZV8yd0H5K YaD9M898AkRJEDRgs5wwdzFRkp3D5DPzPej8qE/l3Kt19Qt8NiA1G4Cu8 j81kGO2rqiWI8UlcE1EDOlEtrpnhAAYiFyuxj4Py5ngNmL4oc0QPP9IIK //nlc3Haup1Z88/olktoySLvkOcFKdErl/c1gaMH2vCqYG/6mU/TWQUEP Q==; X-CSE-ConnectionGUID: HhVyEfOdQ7eS8FBfXggwxA== X-CSE-MsgGUID: 0z2qUV78RaqmR0fDYwsl3Q== X-IronPort-AV: E=McAfee;i="6800,10657,11684"; a="70848791" X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="70848791" Received: from orviesa004.jf.intel.com ([10.64.159.144]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 02:53:12 -0800 X-CSE-ConnectionGUID: ovW0u+ECQoufSNpx8KZjwg== X-CSE-MsgGUID: u5DU4QxtQJmY5yvitTJLIQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.21,258,1763452800"; d="scan'208";a="212787993" Received: from ijarvine-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.245.14]) by orviesa004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2026 02:53:09 -0800 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= To: Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, Andy Shevchenko , qianfan Zhao , Adriana Nicolae Cc: linux-kernel@vger.kernel.org, "Bandal, Shankar" , "Murthy, Shanth" , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Subject: [PATCH v2 0/7] 8250 DW UART fixes when under constant Rx pressure Date: Wed, 28 Jan 2026 12:52:54 +0200 Message-Id: <20260128105301.1869-1-ilpo.jarvinen@linux.intel.com> X-Mailer: git-send-email 2.39.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hi all, Here are fixes to 8250 DW UART conditions that mostly occur in scenarios under constant Rx pressure which are made complicated by BUSY handling of DW UARTs (used when !uart_16550_compatible). A few of the changes touch also 8250_port but it's mostly moving existing code around (except for the extra synchronize_irq() in shutdown). I'll do UART_IIR_RX_TIMEOUT move to switch/case separately from this fix series and a few other cleanups Andy brought up. v2: - Added Fixes tags pointing DW & INTC10EE introducing commits - Added Cc stable to prerequisite patches - Separate adding serial8250_handle_irq_locked() to own patch - Put new exports to SERIAL_8250 namespace (eventually all 8250 exports should move there, but out-of-scope for this series) - Changes to no_int_count - Change type to u8 - Use modulo in increment, add a define for it - Perform kick only on 4th NO_INT - Use serial_port_in/out() throughout the series - Add FIXME comments to ndelay(frame_time) about very low baud rates - Add cleanup.h - Tweak lockdep.h place among misordered includes - Wording tweaks to changelogs and comments Ilpo Järvinen (7): serial: 8250: Protect LCR write in shutdown serial: 8250_dw: Avoid unnecessary LCR writes serial: 8250: Add serial8250_handle_irq_locked() serial: 8250_dw: Rework dw8250_handle_irq() locking and IIR handling serial: 8250_dw: Rework IIR_NO_INT handling to stop interrupt storm serial: 8250: Add late synchronize_irq() to shutdown to handle DW UART BUSY serial: 8250_dw: Ensure BUSY is deasserted drivers/tty/serial/8250/8250.h | 25 +++ drivers/tty/serial/8250/8250_dw.c | 309 ++++++++++++++++++++++------ drivers/tty/serial/8250/8250_port.c | 69 ++++--- include/linux/serial_8250.h | 1 + 4 files changed, 313 insertions(+), 91 deletions(-) base-commit: 8f0b4cce4481fb22653697cced8d0d04027cb1e8 -- 2.39.5