On 04/23/14 22:00, Eric Nelson wrote:
Hi Stefano,
On 04/23/2014 10:07 AM, Stefano Babic wrote:
Hi Tim, hi Nikita,
On 10/04/2014 16:08, Nikita Kiryanov wrote:
The cfg files are currently all written to use the IOMUX register names as MX6_ (no Q vs DL) so that a single cfg file can be used for a build-time configuration of IMX6Q or IMX6DL.
OK now I understand. It seems to me that you only have this problem because you are using these address #defines as values for mx6_mmdc_ioregs structs to define a register mapping. You can also define this mapping by using a struct template that matches the register layout and a base address, both of which change between CPU types.
Reason to do in this way is the thought that the layout among the processsors can be completely different, thing that for other area is also true.
This was discussed also in a previous RFC by Eric:
http://lists.denx.de/pipermail/u-boot/2013-November/166665.htmlTim, what about to repost in your patchset Eric's patch ? It completes your patchset and add documentation that is now missing (added Eric in CC if he will complain about this..)
I have no problem with this, but when I did some follow-on work to bring up SPL on Nitrogen6x boards, I recall finding some bugs in that patch set.
I didn't follow up with updates because I ran into some other snags. In particular, our use of SPI-NOR makes it crucial that we be able to download a secondary U-Boot over USB.
However, if we can recognize the same layout for all three variations (I have only check some registers in 6Q and 6DL layout), using the same structure with a different base address can be even more readable. I admit I have not checked deeply, but it seems at first glance that mx6dq_ctrl and mx6sdl_ctrl in 7/11 share the same layout.
There's a lot of commonality, but a quick diff of arch-mx6/mx6q-ddr.h and arch-mx6/mx6dl-ddr.h will show the problem areas.
You can find an example of this in the Wandboard SPL implementation. It's not in mainline ATM so you'll have to download their BSP. The template + base addr method also doesn't use up additional memory to define this layout, which is a point in its favor.
If the layout is exactly the same, you could make the structure available to all imx6 flavors.
Unfortunately, I don't believe it is.
I also, remember it is not. What Tim says actually makes sense, if layout is not the same, define two structs and choose the right one in runtime.