Hi Janne, thanks for the patch!
On Thu, Mar 23, 2023 at 09:10:12AM +0100, Janne Grunau wrote:
> The Apple SoC devicetrees used to delete unused PCIe ports.
Maybe "used to *omit* unused PCIe ports"? I assume the DT previously
did not mention PCIe ports at all, but now the ports are included but
marked "disabled"?
> Avoid to set
> up disabled PCIe ports to keep the previous behaviour. MacOS initialized
> also only ports with a known device.
The patch is fine with me, but the commit log doesn't tell us why we
want this patch in addition to 6fffbc7ae137 ("PCI: Honor firmware's
device disabled status"), since your previous response [1] says
6fffbc7ae137 already does all the above.
I don't have any Apple specs, but from looking at the code, the
additional benefits of this patch over 6fffbc7ae137 might be:
- We won't trip over DT issues, like "reset" or "reg" not being
defined.
- We won't allocate needless apple_pcie_port structs.
- We won't ioremap register space, assert PERST#, setup clocks and
IRQs.
- We won't sleep waiting for things to come up, potentially saving
150ms or more for each disabled port.
- Maybe there's some power savings; I can't tell.
It's probably more detail than necessary to mention *all* of that, but
the commit log should say *something* about why we want this in
addition to 6fffbc7ae137.
> Use for_each_available_child_of_node instead of for_each_child_of_node
> which takes the "status" property into account.
Would you mind adding "()" after the function names, too? Just my own
idiosyncrasy to help distinguish them from regular English text.
Bjorn
[1] https://lore.kernel.org/r/20230316212217.GI24656@xxxxxxxxxx
> Link: https://lore.kernel.org/asahi/20230214-apple_dts_pcie_disable_unused-v1-0-5ea0d3ddcde3@xxxxxxxxxx/
> Link: https://lore.kernel.org/asahi/1ea2107a-bb86-8c22-0bbc-82c453ab08ce@xxxxxxxxxx/
> Fixes: 1e33888fbe44 ("PCI: apple: Add initial hardware bring-up")
> Reviewed-by: Marc Zyngier <maz@xxxxxxxxxx>
> Signed-off-by: Janne Grunau <j@xxxxxxxxxx>
> ---
> Changes in v3:
> - dropped Cc: stable
> - rewritten commit message since the warning is fixed by 6fffbc7ae137 ("PCI: Honor firmware's
> device disabled status")
> - Link to v2: https://lore.kernel.org/r/20230307-apple_pcie_disabled_ports-v2-1-c3bd1fd278a4@xxxxxxxxxx
>
> Changes in v2:
> - rewritten commit message with more details and corrections
> - collected Marc's "Reviewed-by:"
> - Link to v1: https://lore.kernel.org/r/20230307-apple_pcie_disabled_ports-v1-1-b32ef91faf19@xxxxxxxxxx
> ---
> drivers/pci/controller/pcie-apple.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
> index 66f37e403a09..f8670a032f7a 100644
> --- a/drivers/pci/controller/pcie-apple.c
> +++ b/drivers/pci/controller/pcie-apple.c
> @@ -783,7 +783,7 @@ static int apple_pcie_init(struct pci_config_window *cfg)
> cfg->priv = pcie;
> INIT_LIST_HEAD(&pcie->ports);
>
> - for_each_child_of_node(dev->of_node, of_port) {
> + for_each_available_child_of_node(dev->of_node, of_port) {
> ret = apple_pcie_setup_port(pcie, of_port);
> if (ret) {
> dev_err(pcie->dev, "Port %pOF setup fail: %d\n", of_port, ret);
>
> ---
> base-commit: c9c3395d5e3dcc6daee66c6908354d47bf98cb0c
> change-id: 20230307-apple_pcie_disabled_ports-0c17fb7a4738
>
> Best regards,
> --
> Janne Grunau <j@xxxxxxxxxx>
>
