From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755940AbaIQQew (ORCPT ); Wed, 17 Sep 2014 12:34:52 -0400 Received: from www.linutronix.de ([62.245.132.108]:49928 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755744AbaIQQeu (ORCPT ); Wed, 17 Sep 2014 12:34:50 -0400 Message-ID: <5419B825.5000201@linutronix.de> Date: Wed, 17 Sep 2014 18:34:45 +0200 From: Sebastian Andrzej Siewior User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.0 MIME-Version: 1.0 To: Heikki Krogerus CC: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, tony@atomide.com, balbi@ti.com, gregkh@linuxfoundation.org, Alan Cox Subject: Re: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx References: <1410377411-26656-1-git-send-email-bigeasy@linutronix.de> <1410377411-26656-10-git-send-email-bigeasy@linutronix.de> <20140911111721.GB17476@xps8300> <54118AAB.2010205@linutronix.de> In-Reply-To: <54118AAB.2010205@linutronix.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/11/2014 01:42 PM, Sebastian Andrzej Siewior wrote: >> We should add hooks like tx_dma and rx_dma to struct uart_8250_dma so >> that the probe drivers can replace serial8250_tx_dma and >> seria8250_rx_dma, like I think Alan already suggested. > > Okay. Wasn't aware that Alan already suggested that. > I also need a watchdog timer for TX since it seems that on omap3 the > DMA engine suddenly forgets to continue with DMA… > > If this is really what we want, I would need to refactor a few things… > >> Let's keep serial8250_tx_dma/rx_dma as the default, and not add any >> quirks to them. Only if there is a very common case should it be >> handled in those. The case of RX req needing to be sent before data in >> FIFO maybe one of those, but I'm no sure. > > keep in mind that both (RX & TX bugs/hacks) need also a bit of handling > in the 8250-core so it works together (like the tx_err member so we > fall back to manual xmit) Done. I've kept the RX workarounds in the 8250_dma and moved the TX part into the omap driver. I needed to add the 8250_core pieces of patch #10 [0]. Now If you say, couldn't this done in an other way then I could move the RX workarounds pieces to the omap driver as well as the interrupt routine. Any preferences? [0] [PATCH 10/16] tty: serial: 8250_dma: optimize the xmit path due to UART_BUG_DMA_TX Sebastian