[PATCH 0/4] ARM: imx: Fix problem with imx8 SDRAM size calculation

Joacim Zetterling joacim.zetterling at westermo.com
Fri Feb 25 06:47:47 PST 2022

There is some issues with the imx8 ddrc sdram size calculation.

If we compare the imx8mn DDR4 evk against the LPDDR4 variant in
code and in the datasheets, we see the following:

             DDR4   LPDDR4
  Bus width   16      16
  Rank        1       1
  Ranks       1       1
  Banks       4       8
  Banks grps  2       1
  Rows        17      15
  Col         10      10

This gives us the following problems:

1. Bus width problem.
   Does not support 16 bit SDRAM bus mode, only 32 bit supported

2. Row size problem.
   Only up to 16 bit row size support.

3. Bank groups support.
   Only support of 1 bank group.

4. Bit count problem.
   The imx_ddrc_count_bits function does not do a correct count.
   Found out during test of the 1-3 part fixes.

The fact that the code only handled a 32 bit bus width, compensated
the problems with rows, banks and rank.

This have been tested on the NXP IMX8MN-EVK with 2GB DDR4 SDRAM as
well as on a custom board with 512MB LPDDR4 SDRAM.

Joacim Zetterling (4):
  ARM: imx: Add imx8 support for 18 bit SDRAM row size handle
  ARM: imx: Add imx8 support for SDRAM with two or more bank groups
  ARM: imx: Correct mem size calculation for 4/8/16/32 bit bus width
  ARM: imx: Correct bit count function

 arch/arm/mach-imx/esdctl.c | 61 +++++++++++++++++++++++++-------------
 1 file changed, 41 insertions(+), 20 deletions(-)


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