diff options
| author | Judith Mendez <jm@ti.com> | 2026-09-09 12:38:33 -0500 |
|---|---|---|
| committer | Nishanth Menon <nm@ti.com> | 2026-09-22 08:54:45 -0500 |
| commit | 7dd4fb52749d9726302463dfa2ccf71db6bbed4c (patch) | |
| tree | 8a2ad0fee91c895f5c6d0cbb743395cda23bd8d7 /tools/perf/scripts/python/event_analyzing_sample.py | |
| parent | 0717c94b493171f350f113545f765cd3b71adc50 (diff) | |
arm64: dts: ti: k3-am654-base-board: Add power-off delay for proper MMC power cycle
The AM65x EVM MMC1 VDD rail discharges slowly through RC circuit.
SD spec (section 6.4.1.3) requires VDD < 0.5V for minimum 1ms during
power cycle. Measured discharge time on this board is ~632.97ms to
reach < 0.5V threshold.
During boot, MMC power cycles between boot stages. Without power off
delay, VDD doesn't fully discharge. Card retains 1.8V signaling state
from previous boot stages. When MMC driver later initializes, card no
longer asserts S18A in ACMD41 response (already switched to 1.8V). Host
misinterprets card state and forces 1.8V anyway, falling into a bad
state and causes MMC init failure with "unable to select a mode"
signature.
Add power-off-delay-us = 650000 (650ms) to ensure proper VDD discharge
during power cycles, allowing card to fully reset state between boot
stages.
Signed-off-by: Judith Mendez <jm@ti.com>
Link: https://patch.msgid.link/20260909173833.764103-2-jm@ti.com
Signed-off-by: Nishanth Menon <nm@ti.com>
Diffstat (limited to 'tools/perf/scripts/python/event_analyzing_sample.py')
0 files changed, 0 insertions, 0 deletions