From mboxrd@z Thu Jan 1 00:00:00 1970 From: sre@kernel.org (Sebastian Reichel) Date: Tue, 2 Sep 2014 05:05:46 +0200 Subject: [PATCH 15/15] tty: serial: 8250: omap: add dma support In-Reply-To: <5404B149.6010400@linutronix.de> References: <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> Message-ID: <20140902030546.GB6724@earth.universe> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, On Mon, Sep 01, 2014 at 07:47:53PM +0200, Sebastian Andrzej Siewior wrote: > On 08/29/2014 06:12 PM, Tony Lindgren wrote: > > Looks like the paste bug is there for sure, doing off idle and pasting > > 240 characters to the console can hang the UART RX after few attempts, > > and pasting 16 charactes won't show up at all if the system is idling. > > So you may want to play with that too a bit :) > > One character wakes it up. After that you can send 16, 64 and you see > them. Right away. No delay. > > If you send "a lot" data in one-go it takes approx 152 characters until > the first one is displayed properly at 115200,8N1. That is approx 13ms. > Could it take that long to get up and be ready? I noticed the same behaviour when I tested the runtime PM stuff on my N900 with the existing serial-omap driver and I also assumed, that the chip needs that long to get up. > 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. > > One thing that is probably a dumb idea is that printk in > omap_8250_mdr1_errataset(). > Would it be possible that when I hit a printk in the resume path that I > may deadlock and box will freeze? -- Sebastian -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 819 bytes Desc: Digital signature URL: