Hi Nikolay,
On Wed, Apr 15, 2015 at 8:18 PM, Nikolay Dimitrov picmaster@mail.bg wrote:
This mem_speed (1600) means that the MMDC imx6 code will calculate timings for 1600 MT/s, but in reality the memory clock will be 528 or 532 MHz. It would be better to override the speed to 1066 to make sure imx6 ddr code calculates proper timings.
mem_speed should be retrieved from the DDR3 datasheet.
For clarification, take a look at: board/gateworks/gw_ventana/gw_ventana_spl.c
/* MT41K128M16JT-125 */ static struct mx6_ddr3_cfg mt41k128m16jt_125 = { .mem_speed = 1600,
Looking at the MT41K128M16JT-125 datasheet it says it has a cycle time of 1.25ns, which corresponds to 800MHz. Since this is DDR (double rate) then you get 1600MHz.
To be honest, I don't understand why the code (arch/arm/cpu/armv7 /mx6/ddr.c) supports 1333/1600 MT/s when it's obvious that it's outside chip specs.
The chip is not out of spec. In this ddr.c file we have:
/* MX6D/MX6Q: 1066 MHz memory clock, clkper = 1.894ns = 1894ps */ if (is_cpu_type(MXC_CPU_MX6Q) || is_cpu_type(MXC_CPU_MX6D)) { clock = 528; tcwl = 4; }
And a couple of more notes:
- I see that you don't use the extlinux boot mechanism (from distro
defaults). Do you see any advantages of not using it?
No, I don't. This could be added later.
- Would be nice to have HDMI support :)
Yes, HDMI, USB, PCI, SATA etc. One step at time ;-)
- git patch gives a warning about one empty line
Thanks, I noticed this on the README file and will fix it in v2.
Regards,
Fabio Estevam