Re: [PATCH 2/2] net, thunder, bgx: Add support for ACPI binding.

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On 07.08.2015 13:56, Robert Richter wrote:
On 07.08.15 12:52:41, Tomasz Nowicki wrote:
On 07.08.2015 12:43, Robert Richter wrote:
On 07.08.15 10:09:04, Tomasz Nowicki wrote:
On 07.08.2015 02:33, David Daney wrote:

...

+#else
+
+static int bgx_init_acpi_phy(struct bgx *bgx)
+{
+	return -ENODEV;
+}
+
+#endif /* CONFIG_ACPI */
+
  #if IS_ENABLED(CONFIG_OF_MDIO)

  static int bgx_init_of_phy(struct bgx *bgx)
@@ -882,7 +1010,12 @@ static int bgx_init_of_phy(struct bgx *bgx)

  static int bgx_init_phy(struct bgx *bgx)
  {
-	return bgx_init_of_phy(bgx);
+	int err = bgx_init_of_phy(bgx);
+
+	if (err != -ENODEV)
+		return err;
+
+	return bgx_init_acpi_phy(bgx);
  }


If kernel can work with DT and ACPI (both compiled in), it should take only
one path instead of probing DT and ACPI sequentially. How about:

@@ -902,10 +925,9 @@ static int bgx_probe(struct pci_dev *pdev, const struct
pci_device_id *ent)
  	bgx_vnic[bgx->bgx_id] = bgx;
  	bgx_get_qlm_mode(bgx);

-	snprintf(bgx_sel, 5, "bgx%d", bgx->bgx_id);
-	np = of_find_node_by_name(NULL, bgx_sel);
-	if (np)
-		bgx_init_of(bgx, np);
+	err = acpi_disabled ? bgx_init_of_phy(bgx) : bgx_init_acpi_phy(bgx);
+	if (err)
+		goto err_enable;

  	bgx_init_hw(bgx);

I would not pollute bgx_probe() with acpi and dt specifics, and instead
keep bgx_init_phy(). The typical design pattern for this is:

static int bgx_init_phy(struct bgx *bgx)
{
#ifdef CONFIG_ACPI
         if (!acpi_disabled)
                 return bgx_init_acpi_phy(bgx);
#endif
         return bgx_init_of_phy(bgx);
}

This adds acpi runtime detection (acpi=no), does not call dt code in
case of acpi, and saves the #else for bgx_init_acpi_phy().


I am fine with keeping it in bgx_init_phy(), however we can drop there
#ifdefs since both of bgx_init_{acpi,of}_phy calls have empty stub for !ACPI
and !OF case. Like that:

static int bgx_init_phy(struct bgx *bgx)
{

         if (!acpi_disabled)
                 return bgx_init_acpi_phy(bgx);
	else
         	return bgx_init_of_phy(bgx);
}

As said, keeping it in #ifdefs makes the empty stub function for !acpi
obsolete, which makes the code smaller and better readable. This style
is common practice in the kernel. Apart from that, the 'else' should
be dropped as it is useless.


I would't say the code is better readable (bgx_init_of_phy has still two stubs) but this is just cosmetic, my point was to use run time detection using acpi_disabled.

Tomasz




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