Two answer one of your questions, the gallium driver does not have a non-KMS mode, so the modeset=0 workaround isn't available there. (With some work you may be able to revert to using the non-gallium radeon driver, but let's focus this bug report on fixing the bug itself.)
Two answer one of your questions, the gallium driver does not have a non-KMS mode, so the modeset=0 workaround isn't available there. (With some work you may be able to revert to using the non-gallium radeon driver, but let's focus this bug report on fixing the bug itself.)