diff options
Diffstat (limited to 'libbacklight.c')
| -rw-r--r-- | libbacklight.c | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/libbacklight.c b/libbacklight.c index 1579479..9ab6608 100644 --- a/libbacklight.c +++ b/libbacklight.c @@ -175,6 +175,22 @@ struct backlight *backlight_init(struct pci_device *dev, int card, if (!backlights) return NULL; + /* Find the "best" backlight for the device. Firmware + interfaces are preferred over platform interfaces are + preferred over raw interfaces. For raw interfaces we'll + match if either the pci ID or the output ID match, while + for firmware interfaces we require the pci ID to + match. It's assumed that platform interfaces always match, + since we can't actually associate them with IDs. + + A further awkwardness is that, while it's theoretically + possible for an ACPI interface to include support for + changing the backlight of external devices, it's unlikely + to ever be done. It's effectively impossible for a platform + interface to do so. So if we get asked about anything that + isn't LVDS or eDP, we pretty much have to require that the + control be supplied via a raw interface */ + while ((entry = readdir(backlights))) { char *backlight_path; char *parent; @@ -229,22 +245,13 @@ struct backlight *backlight_init(struct pci_device *dev, int card, parent = basename(buffer); - if (entry_type == BACKLIGHT_RAW) { - if ((drm_name && strcmp(drm_name, parent)) && - (pci_name && strcmp(pci_name, parent))) { + /* Perform matching for raw and firmware backlights - + platform backlights have to be assumed to match */ + if (entry_type == BACKLIGHT_RAW || + entry_type == BACKLIGHT_FIRMWARE) { + if (!((drm_name && !strcmp(drm_name, parent)) || + (pci_name && !strcmp(pci_name, parent)))) goto out; - } - } - - if (entry_type == BACKLIGHT_FIRMWARE) { - /* Older kernels won't provide a valid path here... */ - unsigned int domain, bus, device, function; - ret = sscanf(parent, "%04x:%02x:%02x.%u", &domain, &bus, - &device, &function); - if (ret == 4) { - if (pci_name && strcmp(pci_name, parent)) - goto out; - } } if (entry_type < type) |