From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: [PATCH V6] serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers Date: Mon, 21 Apr 2014 13:39:01 -0600 Message-ID: <535573D5.9050805@wwwdotorg.org> References: <20140417060644.27329.31663.stgit@yunodevel> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from avon.wwwdotorg.org ([70.85.31.133]:41274 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750973AbaDUTpP (ORCPT ); Mon, 21 Apr 2014 15:45:15 -0400 In-Reply-To: <20140417060644.27329.31663.stgit@yunodevel> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Yoshihiro YUNOMAE , Greg Kroah-Hartman , Heikki Krogerus , Stephen Warren , Alan Cc: Jingoo Han , linux-kernel@vger.kernel.org, Hidehiro Kawai , linux-serial@vger.kernel.org, yrl.pp-manager.tt@hitachi.com, Masami Hiramatsu , Aaron Sierra , Jiri Slaby On 04/17/2014 12:06 AM, Yoshihiro YUNOMAE wrote: > Add tunable RX interrupt trigger I/F of FIFO buffers. > Serial devices are used as not only message communication devices but control > or sending communication devices. For the latter uses, normally small data > will be exchanged, so user applications want to receive data unit as soon as > possible for real-time tendency. If we have a sensor which sends a 1 byte data > each time and must control a device based on the sensor feedback, the RX > interrupt should be triggered for each data. > > According to HW specification of serial UART devices, RX interrupt trigger > can be changed, but the trigger is hard-coded. For example, RX interrupt trigger > in 16550A can be set to 1, 4, 8, or 14 bytes for HW, but current driver sets > the trigger to only 8bytes. > > This patch makes some devices change RX interrupt trigger from userland. Reviewed-by: Stephen Warren