From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH 15/15] tty: serial: 8250: omap: add dma support Date: Tue, 2 Sep 2014 13:15:37 -0700 Message-ID: <20140902201536.GC11766@atomide.com> References: <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> <54060EDA.6060204@linutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <54060EDA.6060204@linutronix.de> Sender: linux-omap-owner@vger.kernel.org To: Sebastian Andrzej Siewior 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 List-Id: linux-serial@vger.kernel.org * Sebastian Andrzej Siewior [140902 11:40]: > 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. OK yeah this is the case I was seeing too. So do you just set the LED triggers to none in sysfs to make it easier to reproduce? > - one where the system is dead and the LED does not blink anymore. > Also my button is dead. This I don't think I've seen. This could also be the errata issue on your earlier rev beagleboard-xm with off-idle. > - disabling DMA makes the problem not go away. OK > - 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. I wonder if doing some TX on the uart restores it? So maybe try $ while [ 1 ]; do date; sleep 10 done & To have it occasionally print something in the background. Regards, Tony