On 11/11/2013 10:49 AM, Scott Wood wrote:
On Fri, 2013-11-08 at 20:25 -0600, sun york-R58495 wrote:
On Nov 8, 2013, at 4:48 PM, Scott Wood wrote:
On Wed, 2013-10-30 at 19:07 -0700, York Sun wrote:
CONFIG_SYS_FSL_DDRFreescale DDR driver in use. This type of DDR controller isfound in mpc83xx, mpc85xx, mpc86xx as well as some ARM coreSoCs.CONFIG_SYS_FSL_DDR_ADDRFreescale DDR memory-mapped register base.CONFIG_SYS_FSL_DDR_EMUSpecify emulator support for DDR. Some DDR features such asdeskew training are not available.CONFIG_SYS_FSL_DDR_PPC_GEN1Freescale DDR1 controller.CONFIG_SYS_FSL_DDR_PPC_GEN2Freescale DDR2 controller.CONFIG_SYS_FSL_DDR_PPC_GEN3Freescale DDR3 controller.Why is there "PPC" in the name if this is to be common for PPC and ARM? The description is more generic than the config symbol...
This patch moves the DDR driver out of powerpc. I should deal with the common part for ARM and PPC later. Good point.
CONFIG_FSL_DDR1User config to use DDR1. It can be enabled for SoCs withFreescale DDR1 or DDR2 controllers.CONFIG_FSL_DDR2User config to use DDR2. It can be eanbeld for SoCs withFreescale DDR2 or DDR3 controllers.CONFIG_FSL_DDR3User config to use DDR3. It can be enabled for SoCs withFreescale DDR3 controllers.How is this user config, rather than a description of the type of DDR that is present?
The DDR controller may support more than one type of memory. DDR2 controllers support both DDR1 and DDR2, and some DDR3 controllers support both DDR2 and DDR3. It's user's option to choose which type of DDR devices to use. The driver needs to deal with them differently. You may argue the driver should detect them and choose the algorithm differently. But that will increase the code size considerably. It makes less sense to do so because once the board is designed, it is either this or that.
My point is that the type of DDR that is present is hardware description, just as much as the type of DDR controller. "User config" means things users can choose purely in software, without a corresponding hardware change.
This is a board-level configuration, not SoC level. Should we use CONFIG_SYS_ as well? If so, we need to come up with a new name, such as CONFIG_SYS_FSL_DDR_MEM_GEN3.
York