On Mon, Mar 9, 2015 at 4:52 PM, Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx> wrote: > As GMUX depends on IO for iGP to be enabled and active, lock the IO at > vgaarb level. This should prevent GPU driver for dGPU to disable IO for > iGP while it tries to own legacy VGA IO. > > This fixes usage of backlight control combined with closed nvidia > driver on some Apple dual-GPU (intel/nvidia) systems. > > On those systems loading nvidia driver disables intel IO decoding, > disabling the gmux backlight controls as a side effect. > Prior to commits moving boot_vga from (optional) efifb to less optional > vgaarb this mis-behavior could be avoided by using right kernel config > (efifb enabled but vgaarb disabled). > > This patch explicitly does not try to trigger vgaarb changes in order > to avoid confusing already running graphics drivers. If IO has been > mis-configured by vgaarb gmux will thus fail to probe. > It is expected to load/probe gmux prior to graphics drivers. > > Fixes: ce027dac592c0ada241ce0f95ae65856828ac450 # nvidia interaction > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=86121 > Reported-by: Petri Hodju <petrihodju@xxxxxxxxx> > Tested-by: Petri Hodju <petrihodju@xxxxxxxxx> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > Cc: Matthew Garrett <matthew.garrett@xxxxxxxxxx> > Signed-off-by: Bruno Prémont <bonbons@xxxxxxxxxxxxxxxxx> > --- > Resending v2 in the hope Darren won't hit quoted-printable. > Also adding linux-pci on CC by Bjorn's request in bugzilla. The bugzilla is assigned to PCI, and I was just trying to resolve it. But it looks like Darren might be the logical person to apply this, so I'll ignore it unless poked again. A few minor comments below. > Changes since v1: > - Dropped repeat of gmux in pr_info/pr_err calls > - Mention PCI device we tried to lock IO for in case of error > > > drivers/platform/x86/apple-gmux.c | 43 ++++++++++++++++++++++++++++++++++++++- > 1 file changed, 42 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c > index b9429fb..22da6a3 100644 > --- a/drivers/platform/x86/apple-gmux.c > +++ b/drivers/platform/x86/apple-gmux.c > @@ -22,6 +22,7 @@ > #include <linux/delay.h> > #include <linux/pci.h> > #include <linux/vga_switcheroo.h> > +#include <linux/vgaarb.h> > #include <acpi/video.h> > #include <asm/io.h> > > @@ -31,6 +32,7 @@ struct apple_gmux_data { > bool indexed; > struct mutex index_lock; > > + struct pci_dev *pdev; > struct backlight_device *bdev; > > /* switcheroo data */ > @@ -415,6 +417,22 @@ static int gmux_resume(struct device *dev) > return 0; > } > > +static struct pci_dev *gmux_find_pdev(void) > +{ > + struct pci_dev *pdev = NULL; Typical to have a blank line here (between local variables and code). > + while ((pdev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, pdev))) { > + u16 cmd; > + > + pci_read_config_word(pdev, PCI_COMMAND, &cmd); > + if (!(cmd & PCI_COMMAND_IO)) > + continue; > + > + return pdev; This returns a device with reference count incremented. The convention in PCI, at least, is to name functions that acquire a reference with "_get_", and functions that don't acquire a reference with "_find_". So maybe this function should be renamed? > + } > + > + return NULL; > +} > + > static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > { > struct apple_gmux_data *gmux_data; > @@ -425,6 +443,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > int ret = -ENXIO; > acpi_status status; > unsigned long long gpe; > + struct pci_dev *pdev = NULL; > > if (apple_gmux_data) > return -EBUSY; > @@ -475,7 +494,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > ver_minor = (version >> 16) & 0xff; > ver_release = (version >> 8) & 0xff; > } else { > - pr_info("gmux device not present\n"); > + pr_info("gmux device not present or IO disabled\n"); > ret = -ENODEV; > goto err_release; > } > @@ -483,6 +502,23 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor, > ver_release, (gmux_data->indexed ? "indexed" : "classic")); > > + /* > + * Apple systems with gmux are EFI based and normally don't use > + * VGA. In addition changing IO+MEM ownership between IGP and dGPU > + * disables IO/MEM used for backlight control on some systems. > + * Lock IO+MEM to GPU with active IO to prevent switch. > + */ > + pdev = gmux_find_pdev(); > + if (pdev && vga_tryget(pdev, > + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM)) { > + pr_err("IO+MEM vgaarb-locking for PCI:%s failed\n", > + pci_name(pdev)); It'd be nice to use dev_info/dev_err() for all the messages here, but I see the existing style is to just use pr_info()/pr_err(). So a change to use the dev_ functions would be out of scope for the bug fix itself, but possibly a useful follow-on. > + ret = -EBUSY; > + goto err_release; > + } else if (pdev) > + pr_info("locked IO for PCI:%s\n", pci_name(pdev)); > + gmux_data->pdev = pdev; > + > memset(&props, 0, sizeof(props)); > props.type = BACKLIGHT_PLATFORM; > props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); > @@ -574,6 +609,7 @@ err_enable_gpe: > err_notify: > backlight_device_unregister(bdev); > err_release: > + pci_dev_put(pdev); > release_region(gmux_data->iostart, gmux_data->iolen); > err_free: > kfree(gmux_data); > @@ -593,6 +629,11 @@ static void gmux_remove(struct pnp_dev *pnp) > &gmux_notify_handler); > } > > + if (gmux_data->pdev) { > + vga_put(gmux_data->pdev, > + VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM); > + pci_dev_put(gmux_data->pdev); > + } > backlight_device_unregister(gmux_data->bdev); > > release_region(gmux_data->iostart, gmux_data->iolen); -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
