Raspberry Pi 4 Model B Revision 1.5 and U-Boot >= 2025.07 stalls issue.

[Peter Robinson]

Hi Matteo,

> TFTP downloads in U-Boot >= 2025.07 on Raspberry Pi 4 Model B Revision 1.5
> stall during transfer (continuous T output), while the same setup works
> correctly with U-Boot 2025.04.
>
> Please note that U-Boot starts correctly, DHCP works, and small TFTP still
> works, but large TFTP stalls (e.g., kernel or initramfs files).
>
> On the contrary, Raspberry Pi 4 Model B Revision 1.4 does not have the
> stall issue and can download files correctly up to the latest stable
> version of U-Boot (2026.04).

As far as I can tell from PCN [1] the only difference is the dual RAM
chips so I'm not sure what difference there may be and I only have rev
1.1 and 1.4 of the 4B. Any chance you could do a git bisect between
2025.04 and 2025.07 to work out what change causes the issue?

Peter

[1] https://pip.raspberrypi.com/categories/560-pcn