Re: [PATCH 2/2] PCI: qcom: Add basic interconnect support

Brian Masney
2022-10-20T16:50:08Z

On Mon, Oct 17, 2022 at 01:24:49PM +0200, Johan Hovold wrote:
> On Qualcomm platforms like SC8280XP and SA8540P interconnect bandwidth
> must be requested before enabling interconnect clocks.
>
> Add basic support for managing an optional "pcie-mem" interconnect path
> by setting a low constraint before enabling clocks and updating it after
> the link is up.
>
> Note that it is not possible for a controller driver to set anything but
> a maximum peak bandwidth as expected average bandwidth will vary with
> use case and actual use (and power policy?). This very much remains an
> unresolved problem with the interconnect framework.
>
> Also note that no constraint is set for the SC8280XP/SA8540P "cpu-pcie"
> path for now as it is not clear what an appropriate constraint would be
> (and the system does not crash when left unspecified currently).
>
> Fixes: 70574511f3fc ("PCI: qcom: Add support for SC8280XP")
> Signed-off-by: Johan Hovold <johan+linaro@kernel.org>

Reviewed-by: Brian Masney <bmasney@redhat.com>