Patch "ahci: Acer SA5-271 SSD Not Detected Fix" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    ahci: Acer SA5-271 SSD Not Detected Fix

to the 4.9-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:
     ahci-acer-sa5-271-ssd-not-detected-fix.patch
and it can be found in the queue-4.9 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 8bfd174312629866efa535193d9e563768ff4307 Mon Sep 17 00:00:00 2001
From: Sui Chen <suichen6@gmail.com>
Date: Tue, 9 May 2017 07:47:22 -0500
Subject: ahci: Acer SA5-271 SSD Not Detected Fix

From: Sui Chen <suichen6@gmail.com>

commit 8bfd174312629866efa535193d9e563768ff4307 upstream.

(Correction in this resend: fixed function name acer_sa5_271_workaround; fixed
 the always-true condition in the function; fixed description.)

On the Acer Switch Alpha 12 (model number: SA5-271), the internal SSD may not
get detected because the port_map and CAP.nr_ports combination causes the driver
to skip the port that is actually connected to the SSD. More specifically,
either all SATA ports are identified as DUMMY, or all ports get ``link down''
and never get up again.

This problem occurs occasionally. When this problem occurs, CAP may hold a
value of 0xC734FF00 or 0xC734FF01 and port_map may hold a value of 0x00 or 0x01.
When this problem does not occur, CAP holds a value of 0xC734FF02 and port_map
may hold a value of 0x07. Overriding the CAP value to 0xC734FF02 and port_map to
0x7 significantly reduces the occurrence of this problem.

Link: https://bugzilla.kernel.org/attachment.cgi?id=253091
Signed-off-by: Sui Chen <suichen6@gmail.com>
Tested-by: Damian Ivanov <damianatorrpm@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/ata/ahci.c |   38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1362,6 +1362,40 @@ static inline void ahci_gtf_filter_worka
 {}
 #endif
 
+/*
+ * On the Acer Aspire Switch Alpha 12, sometimes all SATA ports are detected
+ * as DUMMY, or detected but eventually get a "link down" and never get up
+ * again. When this happens, CAP.NP may hold a value of 0x00 or 0x01, and the
+ * port_map may hold a value of 0x00.
+ *
+ * Overriding CAP.NP to 0x02 and the port_map to 0x7 will reveal all 3 ports
+ * and can significantly reduce the occurrence of the problem.
+ *
+ * https://bugzilla.kernel.org/show_bug.cgi?id=189471
+ */
+static void acer_sa5_271_workaround(struct ahci_host_priv *hpriv,
+				    struct pci_dev *pdev)
+{
+	static const struct dmi_system_id sysids[] = {
+		{
+			.ident = "Acer Switch Alpha 12",
+			.matches = {
+				DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
+				DMI_MATCH(DMI_PRODUCT_NAME, "Switch SA5-271")
+			},
+		},
+		{ }
+	};
+
+	if (dmi_check_system(sysids)) {
+		dev_info(&pdev->dev, "enabling Acer Switch Alpha 12 workaround\n");
+		if ((hpriv->saved_cap & 0xC734FF00) == 0xC734FF00) {
+			hpriv->port_map = 0x7;
+			hpriv->cap = 0xC734FF02;
+		}
+	}
+}
+
 #ifdef CONFIG_ARM64
 /*
  * Due to ERRATA#22536, ThunderX needs to handle HOST_IRQ_STAT differently.
@@ -1597,6 +1631,10 @@ static int ahci_init_one(struct pci_dev
 			 "online status unreliable, applying workaround\n");
 	}
 
+
+	/* Acer SA5-271 workaround modifies private_data */
+	acer_sa5_271_workaround(hpriv, pdev);
+
 	/* CAP.NP sometimes indicate the index of the last enabled
 	 * port, at other times, that of the last possible port, so
 	 * determining the maximum port number requires looking at


Patches currently in stable-queue which might be from suichen6@gmail.com are

queue-4.9/ahci-acer-sa5-271-ssd-not-detected-fix.patch