From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Petazzoni Date: Sat, 15 Oct 2016 18:32:51 +0200 Subject: [Buildroot] [PATCH 1/2] configs: update beaglebone_defconfig In-Reply-To: <1474582849-10730-1-git-send-email-lothar.felten@gmail.com> References: <1474582849-10730-1-git-send-email-lothar.felten@gmail.com> Message-ID: <20161015183251.4bc88865@free-electrons.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: buildroot@busybox.net Hello, On Fri, 23 Sep 2016 00:20:48 +0200, Lothar Felten wrote: > This patch updates the target config for the beaglebone based on the AM335x > CPU. It also supports the beagleboneblack, the TI evm and evmsk. > Device tree blobs for am335x-evm, am335x-evmsk, am335x-bone, am335x-boneblack > will be built and a sd card image is created with a post-image script. > The kernel and driver versions match the ti-processor-sdk 02.00.00.00. > Patches allow the use of old AM335x evm revisions (1 bit sd card) and JTAG > debugging. > > Kernel JTAG patch: > By default the kernel will disable the JTAG clock, access via the JTAG port > will not work after the kernel booted. The AM335x-evm has a JTAG header fitted, > this patch keeps the JTAG clock alive. > > Uboot SD card patch: > Early AM335x-evm boards can only use 1 bit communication to the SD card, on > newer board revisions this might be fixed. > Forcing 1 bit communication slows down the communication but will work > regardless if the SD card is attached via 1 or 4 bits. > If the board has a working 4 bit SD card interface, this patch can be removed, > this will speed up the access. > > Signed-off-by: Lothar Felten Thanks, I've applied your patch. However, after discussing with Peter, I removed the 1-bit MMC patch. Indeed, this defconfig is mainly used by BeagleBone users, and this platform is not affected by the 1-bit problem. Therefore, we found it to be really annoying to reduce their MMC performance in U-Boot by a factor of four just because some early 335x EVM boards that almost nobody has access to are broken. If you really want to have a nice support for these early broken boards, then we recommend you to cook a U-Boot patch that detects the board revision, and applies the quirk only in this case. Such a quirk can be upstreamed in U-Boot. Best regards, Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux and Kernel engineering http://free-electrons.com