TMDS64EVM: Change DRAM frequency speed?

Hi Jakub,

Jakub Grad said:

1. How to check at what frequency DRAM is running on hardware?

You could use the `k3conf` tool for this to get the DDR module input frequencies, together with the clock ID for that peripheral (https://software-dl.ti.com/tisci/esd/latest/5_soc_doc/am64x/devices.html#soc-doc-am64x-public-devices-desc-device-list):

$ k3conf dump clock 138

Jakub Grad said:

2. Is there is some place in the code or device tree where default frequency is set for DRAM and how can I change it?

The frequencies are set in the DDR-specific device tree file generated by the DDR config tool (part of SYSCONFIG, https://www.ti.com/tool/SYSCONFIG). For TI boards those can be found in the U-Boot tree like shown here:

$ cat arch/arm/dts/k3-am64-evm-ddr4-1600MTs.dtsi
// SPDX-License-Identifier: GPL-2.0+
/*
 * This file was generated with the
 * AM64x SysConfig DDR Subsystem Register Configuration Tool v0.08.40
 * Wed Feb 02 2022 16:24:50 GMT-0600 (Central Standard Time)
 * DDR Type: DDR4
 * Frequency = 800MHz (1600MTs)
 * Density: 16Gb
 * Number of Ranks: 1
 */

#define DDRSS_PLL_FHS_CNT 6
#define DDRSS_PLL_FREQUENCY_1 400000000         <=== THIS
#define DDRSS_PLL_FREQUENCY_2 400000000         <=== THIS

#define DDRSS_CTL_0_DATA 0x00000A00
#define DDRSS_CTL_1_DATA 0x00000000
#define DDRSS_CTL_2_DATA 0x00000000
<snip>

Note that you should use the tool to setup your DDR parameters including frequencies; don't edit those DTS files directly.

Regards, Andreas