Patch "[PATCH 084/135] ahci: Workaround for ThunderX Errata#22536" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

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

    [PATCH 084/135] ahci: Workaround for ThunderX Errata#22536

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:
     0084-ahci-Workaround-for-ThunderX-Errata-22536.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 <stable@vger.kernel.org> know about it.


>From d72f3eed75067a35153ea20b13a471cee5e67c00 Mon Sep 17 00:00:00 2001
From: Tirumalesh Chalamarla <tchalamarla@caviumnetworks.com>
Date: Tue, 16 Feb 2016 12:08:49 -0800
Subject: [PATCH 084/135] ahci: Workaround for ThunderX Errata#22536

[ Upstream commit d243bed32f5042582896237f88fa1798aee55ff9 ]

Due to Errata in ThunderX, HOST_IRQ_STAT should be
cleared before leaving the interrupt handler.
The patch attempts to satisfy the need.

Changes from V2:
	- removed newfile
	- code is now under CONFIG_ARM64

Changes from V1:
	- Rebased on top of libata/for-4.6
        - Moved ThunderX intr handler to new file

tj: Minor adjustments to comments.

Signed-off-by: Tirumalesh Chalamarla <tchalamarla@caviumnetworks.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/ata/ahci.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1331,6 +1331,44 @@ static inline void ahci_gtf_filter_worka
 {}
 #endif
 
+#ifdef CONFIG_ARM64
+/*
+ * Due to ERRATA#22536, ThunderX needs to handle HOST_IRQ_STAT differently.
+ * Workaround is to make sure all pending IRQs are served before leaving
+ * handler.
+ */
+static irqreturn_t ahci_thunderx_irq_handler(int irq, void *dev_instance)
+{
+	struct ata_host *host = dev_instance;
+	struct ahci_host_priv *hpriv;
+	unsigned int rc = 0;
+	void __iomem *mmio;
+	u32 irq_stat, irq_masked;
+	unsigned int handled = 1;
+
+	VPRINTK("ENTER\n");
+	hpriv = host->private_data;
+	mmio = hpriv->mmio;
+	irq_stat = readl(mmio + HOST_IRQ_STAT);
+	if (!irq_stat)
+		return IRQ_NONE;
+
+	do {
+		irq_masked = irq_stat & hpriv->port_map;
+		spin_lock(&host->lock);
+		rc = ahci_handle_port_intr(host, irq_masked);
+		if (!rc)
+			handled = 0;
+		writel(irq_stat, mmio + HOST_IRQ_STAT);
+		irq_stat = readl(mmio + HOST_IRQ_STAT);
+		spin_unlock(&host->lock);
+	} while (irq_stat);
+	VPRINTK("EXIT\n");
+
+	return IRQ_RETVAL(handled);
+}
+#endif
+
 /*
  * ahci_init_msix() only implements single MSI-X support, not multiple
  * MSI-X per-port interrupts. This is needed for host controllers that only
@@ -1546,6 +1584,11 @@ static int ahci_init_one(struct pci_dev
 	if (ahci_broken_devslp(pdev))
 		hpriv->flags |= AHCI_HFLAG_NO_DEVSLP;
 
+#ifdef CONFIG_ARM64
+	if (pdev->vendor == 0x177d && pdev->device == 0xa01c)
+		hpriv->irq_handler = ahci_thunderx_irq_handler;
+#endif
+
 	/* save initial config */
 	ahci_pci_save_initial_config(pdev, hpriv);
 


Patches currently in stable-queue which might be from tchalamarla@caviumnetworks.com are

queue-4.4/0070-arm64-KVM-Configure-TCR_EL2.PS-at-runtime.patch
queue-4.4/0069-irqchip-gic-v3-Make-sure-read-from-ICC_IAR1_EL1-is-v.patch
queue-4.4/0084-ahci-Workaround-for-ThunderX-Errata-22536.patch