From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Reichel Subject: Re: [PATCH 15/15] tty: serial: 8250: omap: add dma support Date: Tue, 2 Sep 2014 05:05:46 +0200 Message-ID: <20140902030546.GB6724@earth.universe> 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> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="tsOsTdHNUZQcU9Ye" Return-path: Content-Disposition: inline In-Reply-To: <5404B149.6010400@linutronix.de> Sender: linux-kernel-owner@vger.kernel.org To: Sebastian Andrzej Siewior Cc: Tony Lindgren , 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 --tsOsTdHNUZQcU9Ye Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable 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 :) >=20 > One character wakes it up. After that you can send 16, 64 and you see > them. Right away. No delay. >=20 > 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. >=20 > 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 --tsOsTdHNUZQcU9Ye Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBCgAGBQJUBTQJAAoJENju1/PIO/qaw4YP/355aewztKTr/5ipq84jfF60 dAuWXommZrw1dnC1IsOkXpwSiBgb9RErN6mjquWuAaz0ZQ8ZziwuTrGgnsO48lNr 81rx746iCB4AYKR/NBc0hjE5he8B7d+bcNDmAV+FN3tsaKVHcxsJzaDQC0w98lLy +4RKLYufJ7O9wr+0EjmX1wpwhvuVgaVBIXOnbb8FvuvU5vbJqJ6qjRQ41cUke5IE NkkzfNiLJU5R6Is4N1AIsrzTRyt5xxj+3P9z5F38MAbezEzlg5TTWsmDsrUaAi+j gtzz0U6dDztS4yBAFr3a2bEeCnQwbOMgXHtTn6YJxa9atzDcEIz0IYPAYPhBQFQX FUUSHvLBiNYkhgZfjkIsx12bXnSwFu/uXohP95gKoUHNDPJ9CffL9v+nND4sgmeq 3uDUviUiBfTuXNG1mg661F8DuRIITkQx/gKbkR+OblmvCSBoKT8nRGnfxx7Ik/ZS PH5vMi3wAMXyX/UVXI9IuAY6ThyA/rvO1zQeCb+odblMQGJo8HMF1lsXL2BUuEXy SdhTZzsVjrI5tcvNfgG+MlbnuxPO9gw7URvtFgI4QDCJbPVDcn1FQ+8P4DiNOrzU 58VBU0yeElYTp3+DGHNbA6k/RhcjNTiOPRcckBvjuqQak+5H6RU/by2fHjhEbDr3 peSg7DHVMxq5lnsTYQrD =nVOC -----END PGP SIGNATURE----- --tsOsTdHNUZQcU9Ye--