From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Warren Date: Wed, 28 Jan 2009 15:40:49 -0800 Subject: [U-Boot] [PATCH v2 5/9] AVR32: macb - Disable 100mbps if clock is slow In-Reply-To: <20090128231347.GD8355@game.jcrosoft.org> References: <7e5f5fd7693284246714c42b6a3014f82f670b82.1232710611.git.gunnar@rangoy.com> <20090123153856.GA16585@game.jcrosoft.org> <20090128172322.GC8355@game.jcrosoft.org> <20090128224207.48b6ba69@hskinnemoen-d830> <20090128231347.GD8355@game.jcrosoft.org> Message-ID: <4980ED01.6000301@gmail.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Jean-Christophe PLAGNIOL-VILLARD wrote: > On 22:42 Wed 28 Jan , Haavard Skinnemoen wrote: > >> Jean-Christophe PLAGNIOL-VILLARD wrote: >> >>>> On the EVK1100 board, the CPU (UC3A0512) is connected to the PHY via an >>>> RMII bus. This requires the CPU clock to be at least 50 MHz. >>>> Unfortunately, the chip on current EVK1100 boards may be unable to run >>>> at more than 50 MHz, and with the oscillator on the board, the closest >>>> frequency we can generate is 48 MHz. >>>> >>> IMHO It's a HW design error to not use the MII >>> >> Some people want to use the extra pins for other things... >> > make sense > so I'll put a 10Mpbs phy personnaly instead or a 10/100 that can be put in a > 10 mode instead to avoid to manage it in the code > I haven't shopped for PHYs in a while, but imagine it's probably hard to find one that's 10Mb only, and if so it's probably more expensive than 10/100 >> Unfortunately, there are quite a few boards with early engineering >> samples around, and they have various issues. The chips that are in >> production are capable of running fast enough to support RMII. >> >> >>>> This patch makes it possible to limit the macb to 10 MBit for this >>>> case. We are open for suggestions for other solutions. >>>> >>> I guest you may need to disable the phy auto config mode and force him to be >>> see as a 10Mbps phy evenif it's a 10/100 >>> >> No need to disable autonegotiation -- you still want to select between >> half an full duplex, for example. But you'll need to limit the >> available options to the ones that actually work. >> > I do not mean the autoneg but to specify to the phy, if possible, to never > accept the 100Mps instead of do it in the code > That's basically why the advertise register is r/w, so you can limit autonegotiation through software and don't have to allocate pins for strapping. >> That said, I kind of like Ben's suggestion -- it's a more general >> solution to all sorts of board/phy/chip/whatever limitations. >> >> As for a better name, how about CONFIG_MACB_ADVERTISE? >> > why not > I like it too. One of the common checkbox items, though: do any Atmel chips have more than one MACB, in which case this should be CONFIG_MACBx_ADVERTISE or something like that? > Best Regards, > J. > regards, Ben