Re: [PATCH v12 2/6] PCI: mediatek: Add new method to get shared pcie-cfg base address

On Mon, Aug 30, 2021 at 10:31 PM Chuanjia Liu [off-list ref] wrote:

On Mon, 2021-08-30 at 16:43 -0500, Bjorn Helgaas wrote:

quoted

On Mon, Aug 30, 2021 at 03:09:44PM +0800, Chuanjia Liu wrote:

quoted

On Fri, 2021-08-27 at 11:46 -0500, Bjorn Helgaas wrote:

quoted

On Mon, Aug 23, 2021 at 11:27:56AM +0800, Chuanjia Liu wrote:

quoted

@@ -995,6 +1004,14 @@ static int mtk_pcie_subsys_powerup(struct

mtk_pcie *pcie)
                        return PTR_ERR(pcie->base);
        }

+       cfg_node = of_find_compatible_node(NULL, NULL,
+                                          "mediatek,generic-
pciecfg");
+       if (cfg_node) {
+               pcie->cfg = syscon_node_to_regmap(cfg_node);

Other drivers in drivers/pci/controller/ use
syscon_regmap_lookup_by_phandle() (j721e, dra7xx, keystone,
layerscape, artpec6) or syscon_regmap_lookup_by_compatible()
(imx6,
kirin, v3-semi).

You should do it the same way unless there's a need to be
different.

I have used phandle, but Rob suggested to search for the node by
compatible.
The reason why syscon_regmap_lookup_by_compatible() is not
used here is that the pciecfg node is optional, and there is no
need to
return error when the node is not searched.

How about this?

  regmap = syscon_regmap_lookup_by_compatible("mediatek,generic-
pciecfg");
  if (!IS_ERR(regmap))
    pcie->cfg = regmap;

+1

Hi Bjorn,

We need to deal with three situations
1) No error
2) The error of the node not found, don't do anything
3) Other errors, return errors

I guess you mean

regmap = syscon_regmap_lookup_by_compatible("mediatek,generic-
pciecfg");
  if (!IS_ERR(regmap))
      pcie->cfg = regmap;
  else if (IS_ERR(regmap) && PTR_ERR(regmap) != -ENODEV)

You already know  IS_ERR is true here.

      return PTR_ERR(regmap);

syscon_regmap_lookup_by_compatible_optional is the function you are
looking for. The _optional flavor doesn't exist, so create it. There
is one for the phandle lookup.

I'm not sure if we need this, it seems a little weird and there are
many drivers in other subsystems that use syscon_node_to_regmap().

You are implementing the exact same sequence that
syscon_regmap_lookup_by_compatible() does, so clearly you should be
using it. The one difference is you forgot the of_node_put().

Rob

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