From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Fri, 13 Jun 2014 14:21:22 +0000 Subject: Re: [PATCH v2] ARM: shmobile: koelsch: Add support HSCIF1 Message-Id: List-Id: References: <1402367659-21117-1-git-send-email-nobuhiro.iwamatsu.yj@renesas.com> <9058795.dyXpcFtuGJ@avalon> <1751840.oCdYe48VRu@avalon> In-Reply-To: <1751840.oCdYe48VRu@avalon> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: linux-arm-kernel@lists.infradead.org Hi Laurent, On Fri, Jun 13, 2014 at 3:24 PM, Laurent Pinchart wrote: >> About your comment about the resistors and capacitors, which applies to >> both HSCIF0 and HSCIF1: probably the serial port will still work if >> these are present. > > With a 4.7µF capacitive load on the transmission line, assuming a drive > strength of 40mA (which is pretty high), switching between 0V and 3.3V takes > 388µs, corresponding to 2579 Hz. You'll have to reduce the baud rate :-) Right, 4.7µF is a bit high. So at least the capacitor has to go for today's typical serial speeds. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds