From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Andrzej Siewior Subject: Re: [PATCH 15/15] tty: serial: 8250: omap: add dma support Date: Tue, 02 Sep 2014 20:39:22 +0200 Message-ID: <54060EDA.6060204@linutronix.de> References: <20140815210211.GD9239@atomide.com> <53F5AF0D.5060409@linutronix.de> <20140821184416.GF10066@atomide.com> <53FE3779.5090908@linutronix.de> <20140827202313.GF16006@atomide.com> <20140828082348.GA5413@linutronix.de> <20140828164645.GG16006@atomide.com> <53FF84DF.7080406@linutronix.de> <20140828225454.GM16006@atomide.com> <540048B4.7010807@linutronix.de> <20140829161221.GO16006@atomide.com> <5404B149.6010400@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from www.linutronix.de ([62.245.132.108]:38925 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751850AbaIBSjg (ORCPT ); Tue, 2 Sep 2014 14:39:36 -0400 In-Reply-To: <5404B149.6010400@linutronix.de> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Tony Lindgren Cc: balbi@ti.com, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Vinod Koul , Greg Kroah-Hartman , Paul Walmsley On 09/01/2014 07:47 PM, Sebastian Andrzej Siewior wrote: > Comparing it with serial-omap I see the same thing: I takes approx the > same amount of data until the first one is displayed. After a lot of > "long" writes which wake the chip up from idle I manage to freeze both, > the serial-omap driver and mine driver. So after some testing: - it happens with omap-serial as well. Especially after disabling the LED trigger for both LEDs. - it seemed that disabling the MDR1 check whether or not we lost context made the problem appear less often but it was a trick. Even with restoring the context each time I see the same problem. - it seems to be easier to trigger with the LED trigger switched off. However sometimes it works for 10 minutes, sometimes it triggers after one. - I see to face two kind of "deaths": - the LED still goes on and off and the uart just does not respond even if I tell the button print something on the screen (the button also changes the frequency of the LED so I know that the button is doing something). Also from dumping the content of /proc/interrupts it seems that a wake up is made, the uart should have restored the registers. - one where the system is dead and the LED does not blink anymore. Also my button is dead. - disabling DMA makes the problem not go away. - mdelay(25) in omap8250_lost_context() is long enough to drop the 403 bytes I send in my testcase. That means I see only "good" characters. With this the box remained alive for 2h. However the uart died anyway. >> >> Regards, >> >> Tony >> > Sebastian