Hello Hans de Goede,
The patch 315e560c1526: "platform/x86: apple-gmux: Add
acpi_video_get_backlight_type() check" from Mar 7, 2023, leads to the
following Smatch static checker warning:
drivers/platform/x86/apple-gmux.c:974 gmux_probe()
error: uninitialized symbol 'bdev'.
drivers/platform/x86/apple-gmux.c
780 static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
781 {
782 struct apple_gmux_data *gmux_data;
783 struct resource *res;
784 struct backlight_properties props;
785 struct backlight_device *bdev;
786 u8 ver_major, ver_minor, ver_release;
787 bool register_bdev = true;
788 int ret = -ENXIO;
789 acpi_status status;
790 unsigned long long gpe;
791 enum apple_gmux_type type;
792 u32 version;
793
794 if (apple_gmux_data)
795 return -EBUSY;
796
797 if (!apple_gmux_detect(pnp, &type)) {
798 pr_info("gmux device not present\n");
799 return -ENODEV;
800 }
801
802 gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
803 if (!gmux_data)
804 return -ENOMEM;
805 pnp_set_drvdata(pnp, gmux_data);
806
807 switch (type) {
808 case APPLE_GMUX_TYPE_MMIO:
809 gmux_data->config = &apple_gmux_mmio;
810 mutex_init(&gmux_data->index_lock);
811
812 res = pnp_get_resource(pnp, IORESOURCE_MEM, 0);
813 gmux_data->iostart = res->start;
814 /* Although the ACPI table only allocates 8 bytes, we need 16. */
815 gmux_data->iolen = 16;
816 if (!request_mem_region(gmux_data->iostart, gmux_data->iolen,
817 "Apple gmux")) {
818 pr_err("gmux I/O already in use\n");
819 goto err_free;
820 }
821 gmux_data->iomem_base = ioremap(gmux_data->iostart, gmux_data->iolen);
822 if (!gmux_data->iomem_base) {
823 pr_err("couldn't remap gmux mmio region");
824 goto err_release;
825 }
826 goto get_version;
827 case APPLE_GMUX_TYPE_INDEXED:
828 gmux_data->config = &apple_gmux_index;
829 mutex_init(&gmux_data->index_lock);
830 break;
831 case APPLE_GMUX_TYPE_PIO:
832 gmux_data->config = &apple_gmux_pio;
833 break;
834 }
835
836 res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
837 gmux_data->iostart = res->start;
838 gmux_data->iolen = resource_size(res);
839
840 if (!request_region(gmux_data->iostart, gmux_data->iolen,
841 "Apple gmux")) {
842 pr_err("gmux I/O already in use\n");
843 goto err_free;
844 }
845
846 get_version:
847 if (gmux_data->config->read_version_as_u32) {
848 version = gmux_read32(gmux_data, GMUX_PORT_VERSION_MAJOR);
849 ver_major = (version >> 24) & 0xff;
850 ver_minor = (version >> 16) & 0xff;
851 ver_release = (version >> 8) & 0xff;
852 } else {
853 ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
854 ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
855 ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
856 }
857 pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
858 ver_release, gmux_data->config->name);
859
860 memset(&props, 0, sizeof(props));
861 props.type = BACKLIGHT_PLATFORM;
862 props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);
863
864 #if IS_REACHABLE(CONFIG_ACPI_VIDEO)
865 register_bdev = acpi_video_get_backlight_type() == acpi_backlight_apple_gmux;
866 #endif
867 if (register_bdev) {
868 /*
869 * Currently it's assumed that the maximum brightness is less than
870 * 2^24 for compatibility with old gmux versions. Cap the max
871 * brightness at this value, but print a warning if the hardware
872 * reports something higher so that it can be fixed.
873 */
874 if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
875 props.max_brightness = GMUX_MAX_BRIGHTNESS;
876
877 bdev = backlight_device_register("gmux_backlight", &pnp->dev,
878 gmux_data, &gmux_bl_ops, &props);
879 if (IS_ERR(bdev)) {
880 ret = PTR_ERR(bdev);
881 goto err_unmap;
882 }
883
884 gmux_data->bdev = bdev;
885 bdev->props.brightness = gmux_get_brightness(bdev);
886 backlight_update_status(bdev);
887
888 /*
889 * The backlight situation on Macs is complicated. If the gmux is
890 * present it's the best choice, because it always works for
891 * backlight control and supports more levels than other options.
892 * Disable the other backlight choices.
893 */
894 apple_bl_unregister();
895 }
bdev isn't initialized on the error path.
896
897 gmux_data->power_state = VGA_SWITCHEROO_ON;
898
899 gmux_data->dhandle = ACPI_HANDLE(&pnp->dev);
900 if (!gmux_data->dhandle) {
901 pr_err("Cannot find acpi handle for pnp device %s\n",
902 dev_name(&pnp->dev));
903 ret = -ENODEV;
904 goto err_notify;
905 }
906
907 status = acpi_evaluate_integer(gmux_data->dhandle, "GMGP", NULL, &gpe);
908 if (ACPI_SUCCESS(status)) {
909 gmux_data->gpe = (int)gpe;
910
911 status = acpi_install_notify_handler(gmux_data->dhandle,
912 ACPI_DEVICE_NOTIFY,
913 &gmux_notify_handler, pnp);
914 if (ACPI_FAILURE(status)) {
915 pr_err("Install notify handler failed: %s\n",
916 acpi_format_exception(status));
917 ret = -ENODEV;
918 goto err_notify;
919 }
920
921 status = acpi_enable_gpe(NULL, gmux_data->gpe);
922 if (ACPI_FAILURE(status)) {
923 pr_err("Cannot enable gpe: %s\n",
924 acpi_format_exception(status));
925 goto err_enable_gpe;
926 }
927 } else {
928 pr_warn("No GPE found for gmux\n");
929 gmux_data->gpe = -1;
930 }
931
932 /*
933 * If Thunderbolt is present, the external DP port is not fully
934 * switchable. Force its AUX channel to the discrete GPU.
935 */
936 gmux_data->external_switchable =
937 !bus_for_each_dev(&pci_bus_type, NULL, NULL, is_thunderbolt);
938 if (!gmux_data->external_switchable)
939 gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
940
941 apple_gmux_data = gmux_data;
942 init_completion(&gmux_data->powerchange_done);
943 gmux_enable_interrupts(gmux_data);
944 gmux_read_switch_state(gmux_data);
945
946 /*
947 * Retina MacBook Pros cannot switch the panel's AUX separately
948 * and need eDP pre-calibration. They are distinguishable from
949 * pre-retinas by having an "indexed" or "T2" gmux.
950 *
951 * Pre-retina MacBook Pros can switch the panel's DDC separately.
952 */
953 ret = vga_switcheroo_register_handler(gmux_data->config->gmux_handler,
954 gmux_data->config->handler_flags);
955 if (ret) {
956 pr_err("Failed to register vga_switcheroo handler\n");
957 goto err_register_handler;
958 }
959
960 gmux_init_debugfs(gmux_data);
961 return 0;
962
963 err_register_handler:
964 gmux_disable_interrupts(gmux_data);
965 apple_gmux_data = NULL;
966 if (gmux_data->gpe >= 0)
967 acpi_disable_gpe(NULL, gmux_data->gpe);
968 err_enable_gpe:
969 if (gmux_data->gpe >= 0)
970 acpi_remove_notify_handler(gmux_data->dhandle,
971 ACPI_DEVICE_NOTIFY,
972 &gmux_notify_handler);
973 err_notify:
--> 974 backlight_device_unregister(bdev);
^^^^
975 err_unmap:
976 if (gmux_data->iomem_base)
977 iounmap(gmux_data->iomem_base);
978 err_release:
979 if (gmux_data->config->resource_type == IORESOURCE_MEM)
980 release_mem_region(gmux_data->iostart, gmux_data->iolen);
981 else
982 release_region(gmux_data->iostart, gmux_data->iolen);
983 err_free:
984 kfree(gmux_data);
985 return ret;
986 }
regards,
dan carpenter
