From mboxrd@z Thu Jan 1 00:00:00 1970 From: tremyfr@gmail.com (Philippe Reynes) Date: Mon, 11 May 2015 23:25:08 +0200 Subject: [PATCH] imx27: dt: only map 1 Kbyte for fec registers In-Reply-To: <20150511120101.GA25495@tiger> References: <1431204870-17233-1-git-send-email-tremyfr@gmail.com> <20150511120101.GA25495@tiger> Message-ID: <55511E34.5040908@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Shawn, 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.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 at 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. 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. > Shawn Regards, Philippe