CRITICALITY

Medium

DESCRIPTION

The refresh rate is programmed in the EMIF_SDRAM_REFRESH_CONTROL[15:0] REFRESH_RATE parameter and is calculated based off of the frequency of the DDR clock during normal operation.

When a warm reset is applied to the system, the DDR clock source is set to PLL bypass frequency which is much lower than the functional frequency of operation. Due to this frequency change, upon warm reset de-assertion the refresh rate will be too low until the DDR PLL is set to the functional frequency. This could result in unexpected behavior on the memory side.

WORKAROUND

There are 2 possible work-arounds:

1. Use workaround as outlined in Errata i862 to convert warm reset to PORz. Warm reset will function the same as cold reset with this approach.
2. Use external circuitry to apply reset on DDR RESET# pin when warm reset is asserted. DDR contents will be erased upon warm reset with this approach.

REVISIONS IMPACTED

SR 2.0, 1.1, 1.0

TDA2x: 2.0, 1.1, 1.0

DRA75x, DRA74x: 2.0, 1.1, 1.0

AM572x: 2.0, 1.1