From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Return-Path: Date: Fri, 14 Jul 2017 02:35:30 +0100 From: Will Deacon To: Bjorn Helgaas Cc: Daniel Axtens , linux-pci@vger.kernel.org, Xinliang Liu , Rongrong Zou , Catalin Marinas , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4] PCI: Support hibmc VGA cards behind a misbehaving HiSilicon bridge Message-ID: <20170714013529.GF22336@arm.com> References: <20170712050811.3620-1-dja@axtens.net> <20170712200430.GI14614@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20170712200430.GI14614@bhelgaas-glaptop.roam.corp.google.com> List-ID: Hi Bjorn, On Wed, Jul 12, 2017 at 03:04:30PM -0500, Bjorn Helgaas wrote: > [+cc Catalin, Will, linux-arm-kernel] > > On Wed, Jul 12, 2017 at 03:08:11PM +1000, Daniel Axtens wrote: > > The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) that > > are not spec-compliant: the VGA Enable bit is hardwired to 0 and > > writes do not change it. > > > > The HiSilicon engineers report that the bridge does not forward the > > 0xa0000-0xbffff mem range and the 0x3b0-0x3bb and 0x3c0-0x3df I/O > > ranges. > > > > Because the VGA Enable bit is hardwired to 0, the VGA arbiter refuses > > to mark any card behind it as the boot device. This breaks Xorg > > auto-detection. > > > > However, the hibmc VGA card (PCI ID 19e5:1711) has been tested and is > > known to work when behind these bridges. (It does not require the > > legacy resources to operate.) > > > > Provide a quirk so that this combination of bridge and card is eligible > > to be the default VGA card. This fixes Xorg auto-detection on the D05. > > > > Cc: Xinliang Liu > > Cc: Rongrong Zou > > Signed-off-by: Daniel Axtens > > --- > > > > v3: fix commit message > > v4: fix comment (forgot to git add/git commit, sorry for the noise) > > > > --- > > drivers/pci/quirks.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 50 insertions(+) > > > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > > index 16e6cd86ad71..b42324cba29e 100644 > > --- a/drivers/pci/quirks.c > > +++ b/drivers/pci/quirks.c > > @@ -25,6 +25,7 @@ > > #include > > #include > > #include > > +#include > > #include /* isa_dma_bridge_buggy */ > > #include "pci.h" > > > > @@ -4664,3 +4665,52 @@ static void quirk_intel_no_flr(struct pci_dev *dev) > > } > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr); > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr); > > + > > +/* > > + * The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) > > + * that are not spec-compliant: the VGA Enable bit is hardwired to 0 > > + * and writes do not change it. The bridge does not forward legacy > > + * memory or I/O resources. > > + * > > + * Because the VGA Enable bit is hardwired to 0, the VGA arbiter > > + * refuses to mark any card behind it as the boot device. However, the > > + * hibmc VGA card (PCI ID 19e5:1711) has been tested and is known to > > + * work when behind these bridges. > > + * > > + * If we have this bridge, this card, and no default card already, > > + * mark the card as default. > > + */ > > +static void hibmc_fixup_vgaarb(struct pci_dev *pdev) > > +{ > > + struct pci_dev *bridge; > > + struct pci_bus *bus; > > + u16 config; > > + > > + bus = pdev->bus; > > + bridge = bus->self; > > + if (!bridge) > > + return; > > + > > + if (!pci_is_bridge(bridge)) > > + return; > > + > > + if (bridge->vendor != PCI_VENDOR_ID_HUAWEI || > > + bridge->device != 0x1610) > > + return; > > + > > + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, > > + &config); > > + if (config & PCI_BRIDGE_CTL_VGA) { > > + /* > > + * Weirdly, this bridge *is* spec compliant, so bail > > + * and let vgaarb do its job > > + */ > > + return; > > + } > > + > > + if (vga_default_device()) > > + return; > > + > > + vga_set_default_device(pdev); > > +} > > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1711, hibmc_fixup_vgaarb); > > Is this quirk useful on any arch other than arm64? Per > drivers/pci/dwc/Kconfig, CONFIG_PCI_HISI depends on CONFIG_ARM64. > > Would it make sense to put this quirk in arch/arm64/kernel/pci.c? We've resisted adding PCI quirks in the arch directory so far, so I'd rather it lived in the PCI code if you don't have a strong objection to that. Hardware vendors have a tendency to reuse broken IP, so it's not beyond the realms of imagination that this quirk might be needed for another part some day (e.g. based on 32-bit ARM). Will From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 14 Jul 2017 02:35:30 +0100 Subject: [PATCH v4] PCI: Support hibmc VGA cards behind a misbehaving HiSilicon bridge In-Reply-To: <20170712200430.GI14614@bhelgaas-glaptop.roam.corp.google.com> References: <20170712050811.3620-1-dja@axtens.net> <20170712200430.GI14614@bhelgaas-glaptop.roam.corp.google.com> Message-ID: <20170714013529.GF22336@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Bjorn, On Wed, Jul 12, 2017 at 03:04:30PM -0500, Bjorn Helgaas wrote: > [+cc Catalin, Will, linux-arm-kernel] > > On Wed, Jul 12, 2017 at 03:08:11PM +1000, Daniel Axtens wrote: > > The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) that > > are not spec-compliant: the VGA Enable bit is hardwired to 0 and > > writes do not change it. > > > > The HiSilicon engineers report that the bridge does not forward the > > 0xa0000-0xbffff mem range and the 0x3b0-0x3bb and 0x3c0-0x3df I/O > > ranges. > > > > Because the VGA Enable bit is hardwired to 0, the VGA arbiter refuses > > to mark any card behind it as the boot device. This breaks Xorg > > auto-detection. > > > > However, the hibmc VGA card (PCI ID 19e5:1711) has been tested and is > > known to work when behind these bridges. (It does not require the > > legacy resources to operate.) > > > > Provide a quirk so that this combination of bridge and card is eligible > > to be the default VGA card. This fixes Xorg auto-detection on the D05. > > > > Cc: Xinliang Liu > > Cc: Rongrong Zou > > Signed-off-by: Daniel Axtens > > --- > > > > v3: fix commit message > > v4: fix comment (forgot to git add/git commit, sorry for the noise) > > > > --- > > drivers/pci/quirks.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 50 insertions(+) > > > > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > > index 16e6cd86ad71..b42324cba29e 100644 > > --- a/drivers/pci/quirks.c > > +++ b/drivers/pci/quirks.c > > @@ -25,6 +25,7 @@ > > #include > > #include > > #include > > +#include > > #include /* isa_dma_bridge_buggy */ > > #include "pci.h" > > > > @@ -4664,3 +4665,52 @@ static void quirk_intel_no_flr(struct pci_dev *dev) > > } > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1502, quirk_intel_no_flr); > > DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_INTEL, 0x1503, quirk_intel_no_flr); > > + > > +/* > > + * The HiSilicon D05 board has some PCI bridges (PCI ID 19e5:1610) > > + * that are not spec-compliant: the VGA Enable bit is hardwired to 0 > > + * and writes do not change it. The bridge does not forward legacy > > + * memory or I/O resources. > > + * > > + * Because the VGA Enable bit is hardwired to 0, the VGA arbiter > > + * refuses to mark any card behind it as the boot device. However, the > > + * hibmc VGA card (PCI ID 19e5:1711) has been tested and is known to > > + * work when behind these bridges. > > + * > > + * If we have this bridge, this card, and no default card already, > > + * mark the card as default. > > + */ > > +static void hibmc_fixup_vgaarb(struct pci_dev *pdev) > > +{ > > + struct pci_dev *bridge; > > + struct pci_bus *bus; > > + u16 config; > > + > > + bus = pdev->bus; > > + bridge = bus->self; > > + if (!bridge) > > + return; > > + > > + if (!pci_is_bridge(bridge)) > > + return; > > + > > + if (bridge->vendor != PCI_VENDOR_ID_HUAWEI || > > + bridge->device != 0x1610) > > + return; > > + > > + pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, > > + &config); > > + if (config & PCI_BRIDGE_CTL_VGA) { > > + /* > > + * Weirdly, this bridge *is* spec compliant, so bail > > + * and let vgaarb do its job > > + */ > > + return; > > + } > > + > > + if (vga_default_device()) > > + return; > > + > > + vga_set_default_device(pdev); > > +} > > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_HUAWEI, 0x1711, hibmc_fixup_vgaarb); > > Is this quirk useful on any arch other than arm64? Per > drivers/pci/dwc/Kconfig, CONFIG_PCI_HISI depends on CONFIG_ARM64. > > Would it make sense to put this quirk in arch/arm64/kernel/pci.c? We've resisted adding PCI quirks in the arch directory so far, so I'd rather it lived in the PCI code if you don't have a strong objection to that. Hardware vendors have a tendency to reuse broken IP, so it's not beyond the realms of imagination that this quirk might be needed for another part some day (e.g. based on 32-bit ARM). Will