From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heikki Krogerus Subject: Re: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx Date: Fri, 19 Sep 2014 13:22:12 +0300 Message-ID: <20140919102212.GA31784@xps8300> 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> <5419B825.5000201@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mga02.intel.com ([134.134.136.20]:34407 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755437AbaISKWg (ORCPT ); Fri, 19 Sep 2014 06:22:36 -0400 Content-Disposition: inline In-Reply-To: <5419B825.5000201@linutronix.de> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Sebastian Andrzej Siewior 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 On Wed, Sep 17, 2014 at 06:34:45PM +0200, Sebastian Andrzej Siewior wro= te: > 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. > >=20 > > Okay. Wasn't aware that Alan already suggested that. > > I also need a watchdog timer for TX since it seems that on omap3 th= e > > DMA engine suddenly forgets to continue with DMA=E2=80=A6 > >=20 > > If this is really what we want, I would need to refactor a few thin= gs=E2=80=A6 > >=20 > >> Let's keep serial8250_tx_dma/rx_dma as the default, and not add an= y > >> 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 dat= a in > >> FIFO maybe one of those, but I'm no sure. > >=20 > > keep in mind that both (RX & TX bugs/hacks) need also a bit of hand= ling > > in the 8250-core so it works together (like the tx_err member so we > > fall back to manual xmit) >=20 > 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 workaroun= ds > pieces to the omap driver as well as the interrupt routine. Any > preferences? >=20 > [0] [PATCH 10/16] tty: serial: 8250_dma: optimize the xmit path due t= o > UART_BUG_DMA_TX Couldn't you just replace the handle_irq with a custom irq routine in the omap driver like you did with set_termios? Where you would do those tricks and/or call serial8250_handle_irq()? The 8250_core changes in that patch #10 only modify serial8250_handle_irg right? Cheers, --=20 heikki -- To unsubscribe from this list: send the line "unsubscribe linux-serial"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html