[PATCH 4.9 069/104] sata_via: Enable hotplug only on VT6421

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx>


[ Upstream commit 3cf864520e877505158f09075794a08abab11bbe ]

Commit 57e5568fda27 ("sata_via: Implement hotplug for VT6421") adds
hotplug IRQ handler for VT6421 but enables hotplug on all chips. This
is a bug because it causes "irq xx: nobody cared" error on VT6420 when
hot-(un)plugging a drive:

[  381.839948] irq 20: nobody cared (try booting with the "irqpoll" option)
[  381.840014] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.10.0-rc5+ #148
[  381.840066] Hardware name:          P4VM800/P4VM800, BIOS P1.60 05/29/2006
[  381.840117] Call Trace:
[  381.840167]  <IRQ>
[  381.840225]  ? dump_stack+0x44/0x58
[  381.840278]  ? __report_bad_irq+0x14/0x97
[  381.840327]  ? handle_edge_irq+0xa5/0xa5
[  381.840376]  ? note_interrupt+0x155/0x1cf
[  381.840426]  ? handle_edge_irq+0xa5/0xa5
[  381.840474]  ? handle_irq_event_percpu+0x32/0x38
[  381.840524]  ? handle_irq_event+0x1f/0x38
[  381.840573]  ? handle_fasteoi_irq+0x69/0xb8
[  381.840625]  ? handle_irq+0x4f/0x5d
[  381.840672]  </IRQ>
[  381.840726]  ? do_IRQ+0x2e/0x8b
[  381.840782]  ? common_interrupt+0x2c/0x34
[  381.840836]  ? mwait_idle+0x60/0x82
[  381.840892]  ? arch_cpu_idle+0x6/0x7
[  381.840949]  ? do_idle+0x96/0x18e
[  381.841002]  ? cpu_startup_entry+0x16/0x1a
[  381.841057]  ? start_kernel+0x319/0x31c
[  381.841111]  ? startup_32_smp+0x166/0x168
[  381.841165] handlers:
[  381.841219] [<c12a7263>] ata_bmdma_interrupt
[  381.841274] Disabling IRQ #20

Seems that VT6420 can do hotplug too (there's no documentation) but the
comments say that SCR register access (required for detecting hotplug
events) can cause problems on these chips.

For now, just keep hotplug disabled on anything other than VT6421.

Signed-off-by: Ondrej Zary <linux@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/ata/sata_via.c |   18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

--- a/drivers/ata/sata_via.c
+++ b/drivers/ata/sata_via.c
@@ -644,14 +644,16 @@ static void svia_configure(struct pci_de
 		pci_write_config_byte(pdev, SATA_NATIVE_MODE, tmp8);
 	}
 
-	/* enable IRQ on hotplug */
-	pci_read_config_byte(pdev, SVIA_MISC_3, &tmp8);
-	if ((tmp8 & SATA_HOTPLUG) != SATA_HOTPLUG) {
-		dev_dbg(&pdev->dev,
-			"enabling SATA hotplug (0x%x)\n",
-			(int) tmp8);
-		tmp8 |= SATA_HOTPLUG;
-		pci_write_config_byte(pdev, SVIA_MISC_3, tmp8);
+	if (board_id == vt6421) {
+		/* enable IRQ on hotplug */
+		pci_read_config_byte(pdev, SVIA_MISC_3, &tmp8);
+		if ((tmp8 & SATA_HOTPLUG) != SATA_HOTPLUG) {
+			dev_dbg(&pdev->dev,
+				"enabling SATA hotplug (0x%x)\n",
+				(int) tmp8);
+			tmp8 |= SATA_HOTPLUG;
+			pci_write_config_byte(pdev, SVIA_MISC_3, tmp8);
+		}
 	}
 
 	/*