From: "Lothar Waßmann" <LW@KARO-electronics.de>
To: Julien Thierry <julien.thierry@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Dave Airlie <airlied@redhat.com>,
Gabriele Paoloni <gabriele.paoloni@huawei.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-pci@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
dri-devel@lists.freedesktop.org,
Xinliang Liu <z.liuxinliang@hisilicon.com>,
Alex Williamson <alex.williamson@redhat.com>,
Lukas Wunner <lukas@wunner.de>,
Bjorn Helgaas <helgaas@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Rongrong Zou <zourongrong@gmail.com>,
Daniel Vetter <daniel.vetter@intel.com>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH 1/2] vgaarb: Select a default VGA device even if there's no legacy VGA
Date: Thu, 12 Oct 2017 14:05:48 +0200 [thread overview]
Message-ID: <20171012140548.10754506@karo-electronics.de> (raw)
In-Reply-To: <b5373cbb-7d0d-a626-159b-dee0b82d32d0@arm.com>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=
WARNING: multiple messages have this Message-ID (diff)
From: "Lothar Waßmann" <LW@KARO-electronics.de>
To: Julien Thierry <julien.thierry@arm.com>
Cc: Bjorn Helgaas <helgaas@kernel.org>,
Daniel Vetter <daniel.vetter@intel.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Gabriele Paoloni <gabriele.paoloni@huawei.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Will Deacon <will.deacon@arm.com>,
dri-devel@lists.freedesktop.org,
Xinliang Liu <z.liuxinliang@hisilicon.com>,
Alex Williamson <alex.williamson@redhat.com>,
Lukas Wunner <lukas@wunner.de>,
linux-pci@vger.kernel.org, Rongrong Zou <zourongrong@gmail.com>,
Dave Airlie <airlied@redhat.com>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH 1/2] vgaarb: Select a default VGA device even if there's no legacy VGA
Date: Thu, 12 Oct 2017 14:05:48 +0200 [thread overview]
Message-ID: <20171012140548.10754506@karo-electronics.de> (raw)
In-Reply-To: <b5373cbb-7d0d-a626-159b-dee0b82d32d0@arm.com>
Hi,
On Thu, 12 Oct 2017 12:24:10 +0100 Julien Thierry wrote:
> Hi Bjorn,
>=20
> On 06/10/17 23:24, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> >=20
> > 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 arb=
iter
> > never selects it as the default, which means Xorg auto-detection doesn't
> > work.
> >=20
> > 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 a=
re
> > not configurable by BARs. Consequently, multiple VGA devices can confl=
ict
> > with each other. The VGA arbiter avoids conflicts by ensuring that tho=
se
> > legacy resources are only routed to one VGA device at a time.
> >=20
> > The arbiter identifies the "default VGA" device, i.e., a legacy VGA dev=
ice
> > that was used by boot firmware. It selects the first device that:
> >=20
> > - 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.
> >=20
> > 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.
> >=20
> > 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:
> >=20
> > - is of PCI_CLASS_DISPLAY_VGA and
> > - has PCI_COMMAND_IO or PCI_COMMAND_MEMORY enabled
> >=20
> > If it doesn't find even that, it selects the first device that:
> >=20
> > - is of class PCI_CLASS_DISPLAY_VGA.
> >=20
> > 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.
> >=20
> > This fixes Xorg auto-detection on some arm64 systems (HiSilicon D05 in
> > particular; see the link below).
> >=20
> > 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.
> >=20
> > The code here instead selects the *first* enabled VGA device we find, a=
nd
> > if none are enabled, the first VGA device we find.
> >=20
> > Link: http://lkml.kernel.org/r/20170901072744.2409-1-dja@axtens.net
> > Tested-by: Daniel Axtens <dja@axtens.net> # arm64, ppc64-qemu-tcg
> > 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(-)
> >=20
> > 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_hi=
de_host_resource_fsl);
> > DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_FREESCALE, PCI_ANY_ID, fixup_h=
ide_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_dev=
ice())
> > - 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..aeb41f793ed4 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");
> > }
> > =20
> > + if (!vga_default_device()) {
> > + list_for_each_entry(vgadev, &vga_list, list) {
> > + struct device *dev =3D &vgadev->pdev->dev;
> > + u16 cmd;
> > +
> > + pdev =3D 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 =3D list_first_entry_or_null(&vga_list,
> > + struct vga_device, list);
> > + if (vgadev) {
> > + struct device *dev =3D &vgadev->pdev->dev;
> > + vgaarb_info(dev, "setting as boot device (VGA legacy resources not =
available)\n");
> > + vga_set_default_device(pdev);
>=20
> Isn't 'pdev' NULL here? shouldn't it be vgadev->pdev instead?
>=20
That cannot not happen, though it isn't quite obvious.
'vgadev' will only be non-NULL, when the vga_list isn't empty and in
that case pdev has been set up in the list_for_each_entry() loop above.
Lothar Wa=C3=9Fmann
WARNING: multiple messages have this Message-ID (diff)
From: LW@KARO-electronics.de (Lothar Waßmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] vgaarb: Select a default VGA device even if there's no legacy VGA
Date: Thu, 12 Oct 2017 14:05:48 +0200 [thread overview]
Message-ID: <20171012140548.10754506@karo-electronics.de> (raw)
In-Reply-To: <b5373cbb-7d0d-a626-159b-dee0b82d32d0@arm.com>
Hi,
On Thu, 12 Oct 2017 12:24:10 +0100 Julien Thierry wrote:
> Hi Bjorn,
>
> On 06/10/17 23:24, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> >
> > 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 at axtens.net
> > Tested-by: Daniel Axtens <dja@axtens.net> # arm64, ppc64-qemu-tcg
> > 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..aeb41f793ed4 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(pdev);
>
> Isn't 'pdev' NULL here? shouldn't it be vgadev->pdev instead?
>
That cannot not happen, though it isn't quite obvious.
'vgadev' will only be non-NULL, when the vga_list isn't empty and in
that case pdev has been set up in the list_for_each_entry() loop above.
Lothar Wa?mann
WARNING: multiple messages have this Message-ID (diff)
From: "Lothar Waßmann" <LW@KARO-electronics.de>
To: Julien Thierry <julien.thierry@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Dave Airlie <airlied@redhat.com>,
Gabriele Paoloni <gabriele.paoloni@huawei.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-pci@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
dri-devel@lists.freedesktop.org,
Xinliang Liu <z.liuxinliang@hisilicon.com>,
Alex Williamson <alex.williamson@redhat.com>,
Lukas Wunner <lukas@wunner.de>,
Bjorn Helgaas <helgaas@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Rongrong Zou <zourongrong@gmail.com>,
Daniel Vetter <daniel.vetter@intel.com>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org,
Daniel Axtens <dja@axtens.net>
Subject: Re: [PATCH 1/2] vgaarb: Select a default VGA device even if there's no legacy VGA
Date: Thu, 12 Oct 2017 14:05:48 +0200 [thread overview]
Message-ID: <20171012140548.10754506@karo-electronics.de> (raw)
In-Reply-To: <b5373cbb-7d0d-a626-159b-dee0b82d32d0@arm.com>
Hi,
On Thu, 12 Oct 2017 12:24:10 +0100 Julien Thierry wrote:
> Hi Bjorn,
>
> On 06/10/17 23:24, Bjorn Helgaas wrote:
> > From: Bjorn Helgaas <bhelgaas@google.com>
> >
> > 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 <dja@axtens.net> # arm64, ppc64-qemu-tcg
> > 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..aeb41f793ed4 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(pdev);
>
> Isn't 'pdev' NULL here? shouldn't it be vgadev->pdev instead?
>
That cannot not happen, though it isn't quite obvious.
'vgadev' will only be non-NULL, when the vga_list isn't empty and in
that case pdev has been set up in the list_for_each_entry() loop above.
Lothar Waßmann
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2017-10-12 12:05 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-06 22:24 [PATCH 0/2] vgaarb: Select fallback default VGA device Bjorn Helgaas
2017-10-06 22:24 ` Bjorn Helgaas
2017-10-06 22:24 ` Bjorn Helgaas
2017-10-06 22:24 ` [PATCH 1/2] vgaarb: Select a default VGA device even if there's no legacy VGA Bjorn Helgaas
2017-10-06 22:24 ` Bjorn Helgaas
2017-10-12 11:24 ` Julien Thierry
2017-10-12 11:24 ` Julien Thierry
2017-10-12 12:05 ` Lothar Waßmann [this message]
2017-10-12 12:05 ` Lothar Waßmann
2017-10-12 12:05 ` Lothar Waßmann
2017-10-12 12:05 ` Lothar Waßmann
2017-10-12 12:56 ` Julien Thierry
2017-10-12 12:56 ` Julien Thierry
2017-10-13 3:44 ` Bjorn Helgaas
2017-10-13 3:44 ` Bjorn Helgaas
2017-10-06 22:24 ` [PATCH 2/2] vgaarb: Factor out EFI and fallback default device selection Bjorn Helgaas
2017-10-06 22:24 ` Bjorn Helgaas
2017-10-12 10:35 ` [PATCH 0/2] vgaarb: Select fallback default VGA device Sherlock Wang
2017-10-12 10:35 ` Sherlock Wang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20171012140548.10754506@karo-electronics.de \
--to=lw@karo-electronics.de \
--cc=airlied@redhat.com \
--cc=alex.williamson@redhat.com \
--cc=ard.biesheuvel@linaro.org \
--cc=benh@kernel.crashing.org \
--cc=catalin.marinas@arm.com \
--cc=daniel.vetter@intel.com \
--cc=dja@axtens.net \
--cc=dri-devel@lists.freedesktop.org \
--cc=gabriele.paoloni@huawei.com \
--cc=helgaas@kernel.org \
--cc=julien.thierry@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-pci@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=lorenzo.pieralisi@arm.com \
--cc=lukas@wunner.de \
--cc=will.deacon@arm.com \
--cc=z.liuxinliang@hisilicon.com \
--cc=zourongrong@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.