Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754145AbaDYOZB (ORCPT ); Fri, 25 Apr 2014 10:25:01 -0400 Received: from mail-yh0-f50.google.com ([209.85.213.50]:58536 "EHLO mail-yh0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752901AbaDYOY6 (ORCPT ); Fri, 25 Apr 2014 10:24:58 -0400 Date: Fri, 25 Apr 2014 10:24:30 -0400 (EDT) From: Charles Coldwell To: Jon Ringle cc: Charles Coldwell , "linux-serial@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Greg KH , Alexander Shiyan , Jon Ringle Subject: Re: [PATCH v7 1/2] serial: sc16is7xx In-Reply-To: Message-ID: References: <1398387367-4047-1-git-send-email-jon@ringle.org> User-Agent: Alpine 2.03 (LRH 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 25 Apr 2014, Jon Ringle wrote: > On Fri, Apr 25, 2014 at 9:44 AM, Charles Coldwell wrote: > > On Fri, 25 Apr 2014, Charles Coldwell wrote: > > > >> On Thu, 24 Apr 2014, jon@ringle.org wrote: > >> > >> > diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c > >> > >> Isn't this a lot of duplication? > > > > Actually, the whole thing seems like duplication to me. > > The fact that we need to reach over the SPI/I2C bus makes a big > difference in the way access is handled. > > To achieve acceptable throughput, it is necessary to use threaded irq > and also bulk i2c transfers for RX and TX using > regmap_raw_{read,write}() to optimize the use of the i2c bus. Fair enough, but the 8250 framework does allow you to insert your own irq service routine. "serial8250_default_handle_irq" is the default (unsurprisingly), but if the uart_port has a non-NULL "handle_irq" method it will be faithfully copied into the uart_8250_port "handle_irq" method in 8250_core.c:early_serial_setup. > This is not a good fit for 8250. If that's really true, then I would say it argues in favor of a revision of the 8250 code. Certainly, this is not the last time that a 16550-compatible UART will appear on a non-PCI, non-ISA bus. -- Charles M. Coldwell, W1CMC "Turn on, log in, tune out" Somerville, Massachusetts, New England (FN42kj) GPG ID: 852E052F GPG FPR: 77E5 2B51 4907 F08A 7E92 DE80 AFA9 9A8F 852E 052F -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/