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<tremyfr@xxxxxxxxx> > >>--- > >> 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.dtsi > >>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 = "fsl,imx27-fec"; > >>- reg =<0x1002b000 0x4000>; > >>+ reg =<0x1002b000 0x400>; > > > >No. Per MCIMX27RM.pdf, Table 2-7. AIPI2 Memory Map, it should be 4KiB. > > 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 first amount is used. > I'm pleased to understand that we're both agree that 16 Kbyte is too large. > > 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 -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html