Originally by Seth Forshee <seth.forshee@xxxxxxxxxxxxx>, 2012-10-04:
The gmux allows muxing the DDC independently from the display, so
support this functionality. This will allow reading the EDID for the
inactive GPU, fixing issues with machines that either don't have a
VBT or have invalid mode data in the VBT.
Modified by Lukas Wunner <lukas@xxxxxxxxx>, 2015-08-28:
Retain semantics of ->switchto handler callback to switch all pins,
including DDC. Change semantics of ->switch_ddc handler callback to
return previous DDC owner. Original version tried to determine
previous DDC owner with find_active_client() in vga_switcheroo but
this fails if the inactive client registers before the active
client.
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115
Tested-by: Pierre Moreau <pierre.morrow@xxxxxxx>
[MBP 5,3 2009 nvidia MCP79 + G96 pre-retina 15"]
Tested-by: William Brown <william@xxxxxxxxxxxxxxxx>
[MBP 8,2 2011 intel SNB + amd turks pre-retina 15"]
Tested-by: Lukas Wunner <lukas@xxxxxxxxx>
[MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina 15"]
Cc: Seth Forshee <seth.forshee@xxxxxxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
---
drivers/platform/x86/apple-gmux.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 0dec3f5..5bb231b 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -273,6 +273,28 @@ static const struct backlight_ops gmux_bl_ops = {
.update_status = gmux_update_status,
};
+static int gmux_switch_ddc(enum vga_switcheroo_client_id id)
+{
+ enum vga_switcheroo_client_id old_ddc_owner;
+
+ if (gmux_read8(apple_gmux_data, GMUX_PORT_SWITCH_DDC) == 1)
+ old_ddc_owner = VGA_SWITCHEROO_IGD;
+ else
+ old_ddc_owner = VGA_SWITCHEROO_DIS;
+
+ pr_debug("Switching gmux DDC from %d to %d\n", old_ddc_owner, id);
+
+ if (id == old_ddc_owner)
+ return old_ddc_owner;
+
+ if (id == VGA_SWITCHEROO_IGD)
+ gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 1);
+ else
+ gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 2);
+
+ return old_ddc_owner;
+}
+
static int gmux_switchto(enum vga_switcheroo_client_id id)
{
if (id == VGA_SWITCHEROO_IGD) {
@@ -348,6 +370,7 @@ gmux_active_client(struct apple_gmux_data *gmux_data)
static struct vga_switcheroo_handler gmux_handler = {
.switchto = gmux_switchto,
+ .switch_ddc = gmux_switch_ddc,
.power_state = gmux_set_power_state,
.get_client_id = gmux_get_client_id,
};
--
1.8.5.2 (Apple Git-48)
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