ata: ahci: Make ahci_ignore_port() handle empty mask_port_map

Commit 8c87215 ("ata: libahci_platform: support non-consecutive port
numbers") added a skip to ahci_platform_enable_phys() for ports that are
not in mask_port_map.

The code in ahci_platform_get_resources(), will currently set mask_port_map
for each child "port" node it finds in the device tree.

However, device trees that do not have any child "port" nodes will not have
mask_port_map set, and for non-device tree platforms mask_port_map will
only exist as a quirk for specific PCI device + vendor IDs, or as a kernel
module parameter, but will not be set by default.

Therefore, the common thing is that mask_port_map is only set if you do not
want to use all ports (as defined by Offset 0Ch: PI – Ports Implemented
register), but instead only want to use the ports in mask_port_map. If
mask_port_map is not set, all ports are available.

Thus, ahci_ignore_port() must be able to handle an empty mask_port_map.

Fixes: 8c87215 ("ata: libahci_platform: support non-consecutive port numbers")
Fixes: 2c202e6 ("ata: libahci_platform: Do not set mask_port_map when not needed")
Fixes: c9b5be9 ("ahci: Introduce ahci_ignore_port() helper")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Closes: https://lore.kernel.org/linux-ide/10b31dd0-d0bb-4f76-9305-2195c3e17670@samsung.com/
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Co-developed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250225141612.942170-2-cassel@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>

drivers/ata/ahci.h

@@ -386,8 +386,12 @@ struct ahci_host_priv {
 static inline bool ahci_ignore_port(struct ahci_host_priv *hpriv,
 				    unsigned int portid)
 {
-	return portid >= hpriv->nports ||
-		!(hpriv->mask_port_map & (1 << portid));
+	if (portid >= hpriv->nports)
+		return true;
+	/* mask_port_map not set means that all ports are available */
+	if (!hpriv->mask_port_map)
+		return false;
+	return !(hpriv->mask_port_map & (1 << portid));
 }
 
 extern int ahci_ignore_sss;

drivers/ata/libahci.c

@@ -541,6 +541,7 @@ void ahci_save_initial_config(struct device *dev, struct ahci_host_priv *hpriv)
 		hpriv->saved_port_map = port_map;
 	}
 
+	/* mask_port_map not set means that all ports are available */
 	if (hpriv->mask_port_map) {
 		dev_warn(dev, "masking port_map 0x%lx -> 0x%lx\n",
 			port_map,