From patchwork Mon Sep 10 19:10:29 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [1/1,Quantal] UBUNTU: SAUCE: apple-gmux: Fix index read functions From: Seth Forshee X-Patchwork-Id: 182951 Message-Id: <1347304229-6391-2-git-send-email-seth.forshee@canonical.com> To: kernel-team@lists.ubuntu.com Date: Mon, 10 Sep 2012 14:10:29 -0500 From: Bernhard Froemel Study of Apple's binary driver revealed that the GMUX_READ_PORT should be written between calls to gmux_index_wait_ready and gmux_index_wait_complete (i.e., the new index protocol must be followed). If this is not done correctly, the indexed gmux device only partially accepts writes which lead to problems concerning GPU switching. Special thanks to Seth Forshee who helped greatly with identifying unnecessary changes. Signed-off-by: Bernhard Froemel Tested-by: Henrik Rydberg Signed-off-by: Seth Forshee --- drivers/platform/x86/apple-gmux.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 587a603..1146fe5 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -142,8 +142,9 @@ static u8 gmux_index_read8(struct apple_gmux_data *gmux_data, int port) u8 val; mutex_lock(&gmux_data->index_lock); - outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ); gmux_index_wait_ready(gmux_data); + outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ); + gmux_index_wait_complete(gmux_data); val = inb(gmux_data->iostart + GMUX_PORT_VALUE); mutex_unlock(&gmux_data->index_lock); @@ -166,8 +167,9 @@ static u32 gmux_index_read32(struct apple_gmux_data *gmux_data, int port) u32 val; mutex_lock(&gmux_data->index_lock); - outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ); gmux_index_wait_ready(gmux_data); + outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ); + gmux_index_wait_complete(gmux_data); val = inl(gmux_data->iostart + GMUX_PORT_VALUE); mutex_unlock(&gmux_data->index_lock);