For SDK 9.0 to latest, we see that the GTC frequency in the SBL boot flow is 250MHz, whereas in the SPL boot flow it is 200MHz. How to set the GTC to 200MHz in SBL?
Upon looking for the reason for the same, in the SPL boot flow, the source for the GTC was changed from the R5 SPL. But for the SBL boot flow, this was not taken care of.
Hence, you would have to change the clock source in the SBL manually and configure the same to 200 MHz.
One issue that I am seeing with this approach is that the clock frequency is getting reset to 250 Mhz at the beginning of the bootapp.
(If you are loading the Boot App from SBL)
The below patch is built on SDK 9.1 to set the clock frequency of GTC in SBL and BootApp.
After applying this patch in the PDK folder, build the pdk_libs, sbl image and boot app image as shown below
cd ${PDK_PATH}/packages/ti/build
make pdk_libs BOARD=j721s2_evm
make sbl_mmcsd_img BOARD=j721s2_evm
make boot_app_mmcsd_linux BOARD=j721s2_evm
Copy the below 3 binaries to the SD Card and you should see GTC frequency as 200Mhz now.
sudo cp ../boot/sbl/binary/j721s2_evm/mmcsd/bin/sbl_mmcsd_img_mcu1_0_release.tiimage /media/nikhil/BOOT/tiboot3.bin
sudo cp ../drv/sciclient/soc/V4/tifs.bin /media/nikhil/BOOT/tifs.bin
sudo cp ../boot/sbl/example/boot_app/binary/j721s2_evm/mmcsd/sbl_boot_app_mmcsd_linux_j721s2_evm_mcu1_0_freertos_TestApp_release.appimage /media/nikhil/BOOT/app
After this change, boot the EVM and read the GTC clock using the k3conf tool and you should see the GTC set to 200MHz and the clock source changed to MAIN_0_HSDIVOUT6
k3conf dump clock 61
Regards,
Nikhil
