From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH] imx27: dt: only map 1 Kbyte for fec registers Date: Tue, 12 May 2015 09:01:17 +0200 Message-ID: <20150512070117.GV12671@pengutronix.de> References: <1431204870-17233-1-git-send-email-tremyfr@gmail.com> <20150511120101.GA25495@tiger> <55511E34.5040908@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <55511E34.5040908-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Philippe Reynes Cc: Shawn Guo , mark.rutland-5wv7dgnIgG8@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, kernel-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org List-Id: devicetree@vger.kernel.org Hello, On Mon, May 11, 2015 at 11:25:08PM +0200, Philippe Reynes wrote: > On 11/05/15 14:01, Shawn Guo wrote: > >On Sat, May 09, 2015 at 10:54:30PM +0200, Philippe Reynes wrote: > >>According to the imx27 documentation, fec has a 1 Kbyte > >>memory space map, spitted in two regions of 512 bytes. > >>The first one for control/status registers, and the > >>second one for event/statistic registers. So, we don't > >>need to map 16 Kbyte for registers, 1 Kbyte is enough. > >> > >>Signed-off-by: Philippe Reynes > >>--- > >> arch/arm/boot/dts/imx27.dtsi | 2 +- > >> 1 files changed, 1 insertions(+), 1 deletions(-) > >> > >>diff --git a/arch/arm/boot/dts/imx27.dtsi b/arch/arm/boot/dts/imx27= =2Edtsi > >>index 6951b66..56bb917 100644 > >>--- a/arch/arm/boot/dts/imx27.dtsi > >>+++ b/arch/arm/boot/dts/imx27.dtsi > >>@@ -533,7 +533,7 @@ > >> > >> fec: ethernet@1002b000 { > >> compatible =3D "fsl,imx27-fec"; > >>- reg =3D<0x1002b000 0x4000>; > >>+ reg =3D<0x1002b000 0x400>; > > > >No. Per MCIMX27RM.pdf, Table 2-7. AIPI2 Memory Map, it should be 4K= iB. >=20 > I agree, this table show that 4KiB is reserved for fec registers. > But, in paragraph 29.6.1, there is : > "The FEC implementation requires a 1-Kbyte memory map space" > So I've thought that 1 Kbye is enough for the register memory space. The table 2-7 suggests that 4 KiB are routed to the fec even though the fec module might only make use of the first 1 KiB. That's no contradiction. The convention used in the device trees is that the firs= t amount is used. > I'm pleased to understand that we're both agree that 16 Kbyte is too = large. >=20 > If you prefer 4 Kbyte, I'll send a v2 of this patch with this value. Yes please. In the commit log you might want to point out that a length of 16 KiB overlaps with the (currently unused?) Security Controller (SCC) of the i.MX27. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= | -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html