[PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable

[PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable

[gowtham]

The following changes since commit
bb532bfaf7919c7c98caab81864e9ce2646e11e3:

  Linux 7.0.11 (2026-06-01 17:54:55 +0200)

are available in the Git repository at:

  https://github.com/GowthamKudupudi/linux.git
  tags/meson-pcie-warm-reset-linux-7.0.y

for you to fetch changes up to 852811b11795ee389ea6a953ed0db69b76722469:

  PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable
  (2026-06-14 09:41:01 +0530)

----------------------------------------------------------------
PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable

On warm reboot, the PCIe controller's LTSSM starts link training
immediately if PERST# is already deasserted from the previous boot.
The driver then pulses PERST# for only 500us, which is too short to
properly reset the endpoint device that has already started training.

Fix by moving the PERST# assert/deassert pulse BEFORE enabling LTSSM,
so the endpoint gets a clean reset cycle before link training begins.

This was found on Amlogic G12B (A311D) with NVMe on an M.2 slot.
Cold boot worked because POR held PERST# low; warm reboot did not.
The fix was confirmed on a Banana Pi CM4 with Waveshare IO base board.

----------------------------------------------------------------
Gowtham Kudupudi (1):
      PCI: meson: Fix PERST# timing by asserting reset before LTSSM
enable

 drivers/pci/controller/dwc/pci-meson.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Re: [PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable

[Manivannan Sadhasivam]

On Sun, Jun 14, 2026 at 09:56:26AM +0530, gowtham wrote:
> The following changes since commit
> bb532bfaf7919c7c98caab81864e9ce2646e11e3:
> 
>   Linux 7.0.11 (2026-06-01 17:54:55 +0200)
> 
> are available in the Git repository at:
> 
>   https://github.com/GowthamKudupudi/linux.git
>   tags/meson-pcie-warm-reset-linux-7.0.y
> 
> for you to fetch changes up to 852811b11795ee389ea6a953ed0db69b76722469:
> 
>   PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable
>   (2026-06-14 09:41:01 +0530)
> 

Sorry, we don't pull patches from random trees. Please submit the patches to
linux-pci for review.

- Mani

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