I can confirm that the following did indeed work for me on a fresh installation of Fedora 23:
1) Fedora 23 has no sound.
2) Appended the following string to the GRUB_CMDLINE_LINUX parameter in /etc/default/grub: acpi_backlight=vendor acpi_osi='!Windows 2013' acpi_osi='!Windows 2012'
3) Note that Mark's string used backticks instead of single quotes and thus did not work.
4) Ran this command as root: grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
5) Rebooted twice.
6) Sound still did not work immediately. I had to open Sound settings and select the newly discovered "Speakers - Built-in Audio" device.
7) Sound works great! Hurray!
Thanks for helping debug this, everyone. I hope this fix will be incorporated into future Fedora updates by default.
I can confirm that the following did indeed work for me on a fresh installation of Fedora 23:
1) Fedora 23 has no sound. vendor acpi_osi='!Windows 2013' acpi_osi='!Windows 2012' EFI/fedora/ grub.cfg
2) Appended the following string to the GRUB_CMDLINE_LINUX parameter in /etc/default/grub: acpi_backlight=
3) Note that Mark's string used backticks instead of single quotes and thus did not work.
4) Ran this command as root: grub2-mkconfig -o /boot/efi/
5) Rebooted twice.
6) Sound still did not work immediately. I had to open Sound settings and select the newly discovered "Speakers - Built-in Audio" device.
7) Sound works great! Hurray!
Thanks for helping debug this, everyone. I hope this fix will be incorporated into future Fedora updates by default.