[PATCH 06/13] platform/apple-gmux: Add parameter to configure boot gpu

[Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>]

Currently on Indexed and MMIO systems, the system can't change
GPU's on runtime, as the display is not trained on the secondary
GPU, to combat this, we add a module parameter to configure the boot
GPU, so users can change to iGPU or dGPU via reboot.

Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@gmail.com>
---
 drivers/platform/x86/apple-gmux.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 637b3b216..6a9580f27 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -109,6 +109,10 @@ struct apple_gmux_config {
 	char *name;
 };
 
+static int boot_gpu = -1;
+module_param(boot_gpu, int, 0);
+MODULE_PARM_DESC(boot_gpu, "Configure the boot gpu (-1 = auto, 0 = iGPU, 1 = dGPU)");
+
 #define GMUX_INTERRUPT_ENABLE		0xff
 #define GMUX_INTERRUPT_DISABLE		0x00
 
@@ -1215,6 +1219,11 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
 	gmux_enable_interrupts(gmux_data, 1);
 	gmux_read_switch_state(gmux_data);
 
+	if (boot_gpu == 0)
+		gmux_switchto(VGA_SWITCHEROO_IGD);
+	else if (boot_gpu == 1)
+		gmux_switchto(VGA_SWITCHEROO_DIS);
+
 	/*
 	 * Retina MacBook Pros cannot switch the panel's AUX separately
 	 * and need eDP pre-calibration. They are distinguishable from
-- 
2.55.0