Re: [PATCH v5 2/4] dt-bindings: PCI: qcom,pcie-sa8775p: document link_down reset
From: Johan Hovold
Date: Fri Jul 18 2025 - 05:59:33 EST
On Fri, Jul 18, 2025 at 04:17:16PM +0800, Ziyue Zhang wrote:
> Each PCIe controller on SA8775P includes a 'link_down' reset line in
> hardware. This patch documents the reset in the device tree binding.
>
> The 'link_down' reset is used to forcefully bring down the PCIe link
> layer, which is useful in scenarios such as link recovery after errors,
> power management transitions, and hotplug events. Including this reset
> line improves robustness and provides finer control over PCIe controller
> behavior.
>
> As the 'link_down' reset was omitted in the initial submission, it is now
> being documented. While this reset is not required for most of the block's
> basic functionality, and device trees lacking it will continue to function
> correctly in most cases, it is necessary to ensure maximum robustness when
> shutting down or recovering the PCIe core. Therefore, its inclusion is
> justified despite the minor ABI change.
>
> Signed-off-by: Ziyue Zhang <ziyue.zhang@xxxxxxxxxxxxxxxx>
Reviewed-by: Johan Hovold <johan+linaro@xxxxxxxxxx>