Patch "ata: ahci-platform: Add ports-implemented DT bindings." has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

ata: ahci-platform: Add ports-implemented DT bindings.

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
ata-ahci-platform-add-ports-implemented-dt-bindings.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Srinivas Kandagatla <[email protected]>
Date: Fri, 1 Apr 2016 08:52:57 +0100
Subject: ata: ahci-platform: Add ports-implemented DT bindings.

From: Srinivas Kandagatla <[email protected]>

commit 17dcc37e3e847bc0e67a5b1ec52471fcc6c18682 upstream.

On some SOCs PORTS_IMPL register value is never programmed by the firmware and left at zero value. Which means that no sata ports are available for software. AHCI driver used to cope up with this by fabricating the port_map if the PORTS_IMPL register is read zero, but recent patch broke this workaround as zero value was valid for NVMe disks.

This patch adds ports-implemented DT bindings as workaround for this issue in a way that DT can can override the PORTS_IMPL register in cases where the firmware did not program it already.

---
 Documentation/devicetree/bindings/ata/ahci-platform.txt |    4 ++++
 drivers/ata/ahci_platform.c                             |    3 +++
 2 files changed, 7 insertions(+)

@@ -30,6 +30,10 @@ Optional properties:
 - target-supply     : regulator for SATA target power
 - phys              : reference to the SATA PHY node
 - phy-names         : must be "sata-phy"
+- ports-implemented : Mask that indicates which ports that the HBA supports
+		      are available for software to use. Useful if PORTS_IMPL
+		      is not programmed by the BIOS, which is true with
+		      some embedded SOC's.
 
 Required properties when using sub-nodes:
 - #address-cells    : number of cells to encode an address

@@ -51,6 +51,9 @@ static int ahci_probe(struct platform_de
 	if (rc)
 		return rc;
 
+	of_property_read_u32(dev->of_node,
+			     "ports-implemented", &hpriv->force_port_map);
+
 	if (of_device_is_compatible(dev->of_node, "hisilicon,hisi-ahci"))
 		hpriv->flags |= AHCI_HFLAG_NO_FBS | AHCI_HFLAG_NO_NCQ;
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/libahci-save-port-map-for-forced-port-map.patch queue-4.4/clk-qcom-msm8960-fix-ce3_src-register-offset.patch queue-4.4/ata-ahci-platform-add-ports-implemented-dt-bindings.patch queue-4.4/clk-qcom-msm8960-fix-ce3_core-clk-enable-register.patch