* [PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable
@ 2026-06-14 4:26 gowtham
2026-07-01 6:31 ` Manivannan Sadhasivam
0 siblings, 1 reply; 2+ messages in thread
From: gowtham @ 2026-06-14 4:26 UTC (permalink / raw)
To: yue.wang, lpieralisi, kwilczynski, mani
Cc: robh, bhelgaas, neil.armstrong, khilman, jbrunet,
martin.blumenstingl, linux-pci, linux-amlogic, linux-arm-kernel,
linux-kernel
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(-)
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^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable
2026-06-14 4:26 [PULL] PCI: meson: Fix PERST# timing by asserting reset before LTSSM enable gowtham
@ 2026-07-01 6:31 ` Manivannan Sadhasivam
0 siblings, 0 replies; 2+ messages in thread
From: Manivannan Sadhasivam @ 2026-07-01 6:31 UTC (permalink / raw)
To: gowtham
Cc: yue.wang, lpieralisi, kwilczynski, robh, bhelgaas,
neil.armstrong, khilman, jbrunet, martin.blumenstingl, linux-pci,
linux-amlogic, linux-arm-kernel, linux-kernel
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
--
மணிவண்ணன் சதாசிவம்
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