Two fixes found while booting mainline on a Khadas VIM4.

The first one wires uart_a to the real UART bus clock. It was pointed at
the 24MHz crystal as a placeholder, because the T7 clock controller
driver did not exist when these boards were added. That leaves the real
clock without a user, so the kernel turns it off when it disables unused
clocks at the end of boot, and the board hangs with the console gone.

The second one drops regulator-always-on from the SD card supply. A card
that refuses the 1.8V UHS switch can only be recovered by removing its
power, which that property prevents, so the card never initialises and
the MMC core retries forever.

Both were tested on a Khadas VIM4 booting v7.2 from the SD card.

Changes in v2:
- Update UART clocks directly in the board DTS files instead of moving them
   to amlogic-t7.dtsi, as &xtal is defined at the board level.

Lucas Tanure (2):
  arm64: dts: amlogic: t7: use the real UART pclk
  arm64: dts: amlogic: t7: khadas-vim4: allow the SD card to be power
    cycled

 arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts       | 2 +-
 arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

-- 
2.55.0

Hi,

On Sun, 23 Aug 2026 12:53:33 +0100, Lucas Tanure wrote:
> Two fixes found while booting mainline on a Khadas VIM4.
> 
> The first one wires uart_a to the real UART bus clock. It was pointed at
> the 24MHz crystal as a placeholder, because the T7 clock controller
> driver did not exist when these boards were added. That leaves the real
> clock without a user, so the kernel turns it off when it disables unused
> clocks at the end of boot, and the board hangs with the console gone.
> 
> [...]

Thanks, Applied to https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git (v7.3/fixes)

[1/2] arm64: dts: amlogic: t7: use the real UART pclk
      https://git.kernel.org/amlogic/c/882de800bf583dd15969836088789edbf035a944
[2/2] arm64: dts: amlogic: t7: khadas-vim4: allow the SD card to be power cycled
      https://git.kernel.org/amlogic/c/c793a084ab3088744516aef437b4239d0d98623f

These changes has been applied on the intermediate git tree [1].

The v7.3/fixes branch will then be sent via a formal Pull Request to the Linux SoC maintainers
for inclusion in their intermediate git branches in order to be sent to Linus during
the next merge window, or sooner if it's a set of fixes.

In the cases of fixes, those will be merged in the current release candidate
kernel and as soon they appear on the Linux master branch they will be
backported to the previous Stable and Long-Stable kernels [2].

The intermediate git branches are merged daily in the linux-next tree [3],
people are encouraged testing these pre-release kernels and report issues on the
relevant mailing-lists.

If problems are discovered on those changes, please submit a signed-off-by revert
patch followed by a corrective changeset.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/amlogic/linux.git
[2] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
[3] https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git

-- 
Neil