[PATCH v2 0/2] vgaarb: Select fallback default VGA device

These patches are supposed to fix a problem Daniel Axtens found on the
HiSilicon D05 board.  The VGA device there is behind a bridge that doesn't
support PCI_BRIDGE_CTL_VGA, so the arbiter never selects the device as the
default.

The first patch extends the arbiter so that if it can't find an enabled VGA
device with legacy resources, it selects the first enabled device *without*
legacy resources (this is what fixes the D05).  If that fails, it selects
the first device that isn't enabled.  The combination of both changes
should make the current powerpc fixup_vga() quirk unnecessary.

N.B. It changes the powerpc behavior: if there are several enabled VGA
devices, the current quirk selects the last one, while this patch selects
the first one.  If this is a problem, I can drop that part of the patch and
keep the quirk.

The second patch pulls out this fallback device detection (and the EFI
override) from vga_arb_device_init() to make it easier to read.

Changes in v2:
  - set default device to vgadev->pdev instead of the pdev left over from a
    previous iteration through the list (thanks to Julien Thierry)

  - added "Tested-by: Zhou Wang" (I'm pretty sure the change above doesn't
    invalidate this testing)

---

Bjorn Helgaas (2):
      vgaarb: Select a default VGA device even if there's no legacy VGA
      vgaarb: Factor out EFI and fallback default device selection


 arch/powerpc/kernel/pci-common.c |   12 ------
 drivers/gpu/vga/vgaarb.c         |   72 +++++++++++++++++++++++++++++---------
 2 files changed, 55 insertions(+), 29 deletions(-)

Daniel Axtens reported that on the HiSilicon D05 board, the VGA device is
behind a bridge that doesn't support PCI_BRIDGE_CTL_VGA, so the VGA arbiter
never selects it as the default, which means Xorg auto-detection doesn't
work.

VGA is a legacy PCI feature: a VGA device can respond to addresses, e.g.,
[mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], [io 0x3c0-0x3df], etc., that are
not configurable by BARs.  Consequently, multiple VGA devices can conflict
with each other.  The VGA arbiter avoids conflicts by ensuring that those
legacy resources are only routed to one VGA device at a time.

The arbiter identifies the "default VGA" device, i.e., a legacy VGA device
that was used by boot firmware.  It selects the first device that:

  - is of PCI_CLASS_DISPLAY_VGA,
  - has both PCI_COMMAND_IO and PCI_COMMAND_MEMORY enabled, and
  - has PCI_BRIDGE_CTL_VGA set in all upstream bridges.

Some systems don't have such a device.  For example, if a host bridge
doesn't support I/O space, PCI_COMMAND_IO probably won't be enabled for any
devices below it.  Or, as on the HiSilicon D05, the VGA device may be
behind a bridge that doesn't support PCI_BRIDGE_CTL_VGA, so accesses to the
legacy VGA resources will never reach the device.

This patch extends the arbiter so that if it doesn't find a device that
meets all the above criteria, it selects the first device that:

  - is of PCI_CLASS_DISPLAY_VGA and
  - has PCI_COMMAND_IO or PCI_COMMAND_MEMORY enabled

If it doesn't find even that, it selects the first device that:

  - is of class PCI_CLASS_DISPLAY_VGA.

Such a device may not be able to use the legacy VGA resources, but most
drivers can operate the device without those.  Setting it as the default
device means its "boot_vga" sysfs file will contain "1", which Xorg (via
libpciaccess) uses to help select its default output device.

This fixes Xorg auto-detection on some arm64 systems (HiSilicon D05 in
particular; see the link below).

It also replaces the powerpc fixup_vga() quirk, albeit with slightly
different semantics: the quirk selected the first VGA device we found, and
overrode that selection with any enabled VGA device we found.  If there
were several enabled VGA devices, the *last* one we found would become the
default.

The code here instead selects the *first* enabled VGA device we find, and
if none are enabled, the first VGA device we find.

Link: http://lkml.kernel.org/r/20170901072744.2409-1-dja@axtens.net
Tested-by: Daniel Axtens <redacted>       # arm64, ppc64-qemu-tcg
Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 arch/powerpc/kernel/pci-common.c |   12 ------------
 drivers/gpu/vga/vgaarb.c         |   25 +++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
index 02831a396419..0ac7aa346c69 100644
--- a/arch/powerpc/kernel/pci-common.c
+++ b/arch/powerpc/kernel/pci-common.c

@@ -1740,15 +1740,3 @@ static void fixup_hide_host_resource_fsl(struct pci_dev *dev)
 }
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_MOTOROLA, PCI_ANY_ID, fixup_hide_host_resource_fsl);
 DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, fixup_hide_host_resource_fsl);
-
-static void fixup_vga(struct pci_dev *pdev)
-{
-	u16 cmd;
-
-	pci_read_config_word(pdev, PCI_COMMAND, &cmd);
-	if ((cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) || !vga_default_device())
-		vga_set_default_device(pdev);
-
-}
-DECLARE_PCI_FIXUP_CLASS_FINAL(PCI_ANY_ID, PCI_ANY_ID,
-			      PCI_CLASS_DISPLAY_VGA, 8, fixup_vga);

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 76875f6299b8..8035e38d5110 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c

@@ -1468,6 +1468,31 @@ static int __init vga_arb_device_init(void)
 			vgaarb_info(dev, "no bridge control possible\n");
 	}
 
+	if (!vga_default_device()) {
+		list_for_each_entry(vgadev, &vga_list, list) {
+			struct device *dev = &vgadev->pdev->dev;
+			u16 cmd;
+
+			pdev = vgadev->pdev;
+			pci_read_config_word(pdev, PCI_COMMAND, &cmd);
+			if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
+				vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
+				vga_set_default_device(pdev);
+				break;
+			}
+		}
+	}
+
+	if (!vga_default_device()) {
+		vgadev = list_first_entry_or_null(&vga_list,
+						  struct vga_device, list);
+		if (vgadev) {
+			struct device *dev = &vgadev->pdev->dev;
+			vgaarb_info(dev, "setting as boot device (VGA legacy resources not available)\n");
+			vga_set_default_device(vgadev->pdev);
+		}
+	}
+
 	pr_info("loaded\n");
 	return rc;
 }

The default VGA device is normally set in vga_arbiter_add_pci_device() when
we call it for the first enabled device that can be accessed with the
legacy VGA resources ([mem 0xa0000-0xbffff], etc.)

That default device can be overridden by an EFI device that owns the boot
framebuffer.  As a fallback, we can also select a VGA device that can't be
accessed via legacy VGA resources, or a VGA device that isn't even enabled.

Factor out this EFI and fallback selection from vga_arb_device_init() into
a separate vga_arb_select_default_device() function.  This doesn't change
any behavior, but it untangles the "bridge control possible" checking and
messages from the default device selection.

Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 8035e38d5110..d35d6d271f3f 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c

@@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
 	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
 };
 
-static int __init vga_arb_device_init(void)
+static void __init vga_arb_select_default_device(void)
 {
-	int rc;
 	struct pci_dev *pdev;
 	struct vga_device *vgadev;
 
-	rc = misc_register(&vga_arb_device);
-	if (rc < 0)
-		pr_err("error %d registering device\n", rc);
-
-	bus_register_notifier(&pci_bus_type, &pci_notifier);
-
-	/* We add all pci devices satisfying vga class in the arbiter by
-	 * default */
-	pdev = NULL;
-	while ((pdev =
-		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
-			       PCI_ANY_ID, pdev)) != NULL)
-		vga_arbiter_add_pci_device(pdev);
-
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 	list_for_each_entry(vgadev, &vga_list, list) {
 		struct device *dev = &vgadev->pdev->dev;
-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 		/*
 		 * Override vga_arbiter_add_pci_device()'s I/O based detection
 		 * as it may take the wrong device (e.g. on Apple system under

@@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
 				vgaarb_info(dev, "overriding boot device\n");
 			vga_set_default_device(vgadev->pdev);
 		}
-#endif
-		if (vgadev->bridge_has_one_vga)
-			vgaarb_info(dev, "bridge control possible\n");
-		else
-			vgaarb_info(dev, "no bridge control possible\n");
 	}
+#endif
 
 	if (!vga_default_device()) {
 		list_for_each_entry(vgadev, &vga_list, list) {

@@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
 			vga_set_default_device(vgadev->pdev);
 		}
 	}
+}
+
+static int __init vga_arb_device_init(void)
+{
+	int rc;
+	struct pci_dev *pdev;
+	struct vga_device *vgadev;
+
+	rc = misc_register(&vga_arb_device);
+	if (rc < 0)
+		pr_err("error %d registering device\n", rc);
+
+	bus_register_notifier(&pci_bus_type, &pci_notifier);
+
+	/* We add all PCI devices satisfying VGA class in the arbiter by
+	 * default */
+	pdev = NULL;
+	while ((pdev =
+		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+			       PCI_ANY_ID, pdev)) != NULL)
+		vga_arbiter_add_pci_device(pdev);
+
+	list_for_each_entry(vgadev, &vga_list, list) {
+		struct device *dev = &vgadev->pdev->dev;
+
+		if (vgadev->bridge_has_one_vga)
+			vgaarb_info(dev, "bridge control possible\n");
+		else
+			vgaarb_info(dev, "no bridge control possible\n");
+	}
+
+	vga_arb_select_default_device();
 
 	pr_info("loaded\n");
 	return rc;

Bjorn Helgaas [off-list ref] writes:

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

Regards,
Daniel

+
+	vga_arb_select_default_device();
 
 	pr_info("loaded\n");
 	return rc;

On Tue, Oct 17, 2017 at 01:03:46PM +1100, Daniel Axtens wrote:

Bjorn Helgaas [off-list ref] writes:

quoted

The default VGA device is normally set in vga_arbiter_add_pci_device() when
we call it for the first enabled device that can be accessed with the
legacy VGA resources ([mem 0xa0000-0xbffff], etc.)

That default device can be overridden by an EFI device that owns the boot
framebuffer.  As a fallback, we can also select a VGA device that can't be
accessed via legacy VGA resources, or a VGA device that isn't even enabled.

Factor out this EFI and fallback selection from vga_arb_device_init() into
a separate vga_arb_select_default_device() function.  This doesn't change
any behavior, but it untangles the "bridge control possible" checking and
messages from the default device selection.

Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 8035e38d5110..d35d6d271f3f 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c

@@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
 	MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
 };
 
-static int __init vga_arb_device_init(void)
+static void __init vga_arb_select_default_device(void)
 {
-	int rc;
 	struct pci_dev *pdev;
 	struct vga_device *vgadev;
 
-	rc = misc_register(&vga_arb_device);
-	if (rc < 0)
-		pr_err("error %d registering device\n", rc);
-
-	bus_register_notifier(&pci_bus_type, &pci_notifier);
-
-	/* We add all pci devices satisfying vga class in the arbiter by
-	 * default */
-	pdev = NULL;
-	while ((pdev =
-		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
-			       PCI_ANY_ID, pdev)) != NULL)
-		vga_arbiter_add_pci_device(pdev);
-
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 	list_for_each_entry(vgadev, &vga_list, list) {
 		struct device *dev = &vgadev->pdev->dev;
-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
 		/*
 		 * Override vga_arbiter_add_pci_device()'s I/O based detection
 		 * as it may take the wrong device (e.g. on Apple system under

@@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
 				vgaarb_info(dev, "overriding boot device\n");
 			vga_set_default_device(vgadev->pdev);
 		}
-#endif
-		if (vgadev->bridge_has_one_vga)
-			vgaarb_info(dev, "bridge control possible\n");
-		else
-			vgaarb_info(dev, "no bridge control possible\n");
 	}
+#endif
 
 	if (!vga_default_device()) {
 		list_for_each_entry(vgadev, &vga_list, list) {

@@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
 			vga_set_default_device(vgadev->pdev);
 		}
 	}
+}
+
+static int __init vga_arb_device_init(void)
+{
+	int rc;
+	struct pci_dev *pdev;
+	struct vga_device *vgadev;
+
+	rc = misc_register(&vga_arb_device);
+	if (rc < 0)
+		pr_err("error %d registering device\n", rc);
+
+	bus_register_notifier(&pci_bus_type, &pci_notifier);
+
+	/* We add all PCI devices satisfying VGA class in the arbiter by
+	 * default */
+	pdev = NULL;
+	while ((pdev =
+		pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+			       PCI_ANY_ID, pdev)) != NULL)
+		vga_arbiter_add_pci_device(pdev);
+
+	list_for_each_entry(vgadev, &vga_list, list) {
+		struct device *dev = &vgadev->pdev->dev;
+
+		if (vgadev->bridge_has_one_vga)
+			vgaarb_info(dev, "bridge control possible\n");
+		else
+			vgaarb_info(dev, "no bridge control possible\n");
+	}

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

On 17 October 2017 at 13:05, Daniel Vetter [off-list ref] wrote:

On Tue, Oct 17, 2017 at 01:03:46PM +1100, Daniel Axtens wrote:

quoted

Bjorn Helgaas [off-list ref] writes:

quoted

The default VGA device is normally set in vga_arbiter_add_pci_device() when
we call it for the first enabled device that can be accessed with the
legacy VGA resources ([mem 0xa0000-0xbffff], etc.)

That default device can be overridden by an EFI device that owns the boot
framebuffer.  As a fallback, we can also select a VGA device that can't be
accessed via legacy VGA resources, or a VGA device that isn't even enabled.

Factor out this EFI and fallback selection from vga_arb_device_init() into
a separate vga_arb_select_default_device() function.  This doesn't change
any behavior, but it untangles the "bridge control possible" checking and
messages from the default device selection.

Tested-by: Zhou Wang <wangzhou1@hisilicon.com>  # D05 Hisi Hip07, Hip08
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/gpu/vga/vgaarb.c |   57 ++++++++++++++++++++++++++++------------------
 1 file changed, 35 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
index 8035e38d5110..d35d6d271f3f 100644
--- a/drivers/gpu/vga/vgaarb.c
+++ b/drivers/gpu/vga/vgaarb.c

@@ -1402,29 +1402,14 @@ static struct miscdevice vga_arb_device = {
    MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
 };

-static int __init vga_arb_device_init(void)
+static void __init vga_arb_select_default_device(void)
 {
-   int rc;
    struct pci_dev *pdev;
    struct vga_device *vgadev;

-   rc = misc_register(&vga_arb_device);
-   if (rc < 0)
-           pr_err("error %d registering device\n", rc);
-
-   bus_register_notifier(&pci_bus_type, &pci_notifier);
-
-   /* We add all pci devices satisfying vga class in the arbiter by
-    * default */
-   pdev = NULL;
-   while ((pdev =
-           pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
-                          PCI_ANY_ID, pdev)) != NULL)
-           vga_arbiter_add_pci_device(pdev);
-
+#if defined(CONFIG_X86) || defined(CONFIG_IA64)
    list_for_each_entry(vgadev, &vga_list, list) {
            struct device *dev = &vgadev->pdev->dev;
-#if defined(CONFIG_X86) || defined(CONFIG_IA64)
            /*
             * Override vga_arbiter_add_pci_device()'s I/O based detection
             * as it may take the wrong device (e.g. on Apple system under

@@ -1461,12 +1446,8 @@ static int __init vga_arb_device_init(void)
                            vgaarb_info(dev, "overriding boot device\n");
                    vga_set_default_device(vgadev->pdev);
            }
-#endif
-           if (vgadev->bridge_has_one_vga)
-                   vgaarb_info(dev, "bridge control possible\n");
-           else
-                   vgaarb_info(dev, "no bridge control possible\n");
    }
+#endif

    if (!vga_default_device()) {
            list_for_each_entry(vgadev, &vga_list, list) {

@@ -1492,6 +1473,38 @@ static int __init vga_arb_device_init(void)
                    vga_set_default_device(vgadev->pdev);
            }
    }
+}
+
+static int __init vga_arb_device_init(void)
+{
+   int rc;
+   struct pci_dev *pdev;
+   struct vga_device *vgadev;
+
+   rc = misc_register(&vga_arb_device);
+   if (rc < 0)
+           pr_err("error %d registering device\n", rc);
+
+   bus_register_notifier(&pci_bus_type, &pci_notifier);
+
+   /* We add all PCI devices satisfying VGA class in the arbiter by
+    * default */
+   pdev = NULL;
+   while ((pdev =
+           pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
+                          PCI_ANY_ID, pdev)) != NULL)
+           vga_arbiter_add_pci_device(pdev);
+
+   list_for_each_entry(vgadev, &vga_list, list) {
+           struct device *dev = &vgadev->pdev->dev;
+
+           if (vgadev->bridge_has_one_vga)
+                   vgaarb_info(dev, "bridge control possible\n");
+           else
+                   vgaarb_info(dev, "no bridge control possible\n");
+   }

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

For both patches

Acked-by: Ard Biesheuvel <redacted>

Hi Daniel,

quoted

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

I had only intended it for patch 2, but I've now read over patch 1 to my
satisfaction, so it too is:

Reviewed-by: Daniel Axtens <redacted>

Thanks!

Regards,
Daniel

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

On Wed, Oct 18, 2017 at 11:24:43AM +1100, Daniel Axtens wrote:

Hi Daniel,

quoted

quoted

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

I had only intended it for patch 2, but I've now read over patch 1 to my
satisfaction, so it too is:

Reviewed-by: Daniel Axtens <redacted>

Both applied for 4.15, thanks.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

Daniel Vetter [off-list ref] writes:

On Wed, Oct 18, 2017 at 11:24:43AM +1100, Daniel Axtens wrote:

quoted

Hi Daniel,

quoted

quoted

Initially I wondered if this info printk could be moved into
vga_arbiter_check_bridge_sharing(), but it's been separated out since
3448a19da479b ("vgaarb: use bridges to control VGA routing where
possible."), and upon closer examination, it seems you can't be sure a
device doesn't share a bridge until the end of the process, so this is
indeed correct.

Everything else also looks good to me.

Reviewed-by: Daniel Axtens <redacted>

R-b for both patches? And ok with everyone if I pull this into drm-misc
for 4.15 (deadline is end of this week for feature-y stuff)?

I had only intended it for patch 2, but I've now read over patch 1 to my
satisfaction, so it too is:

Reviewed-by: Daniel Axtens <redacted>

Both applied for 4.15, thanks.

Cool - thanks!

A special thanks to Bjorn for persisting with this and coming up with a
nice simple solution :)

Regards,
Daniel

-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch