vga_switcheroo: initial implementation (v15)

Many new laptops now come with 2 gpus, one to be used for low power
modes and one for gaming/on-ac applications. These GPUs are typically
wired to the laptop panel and VGA ports via a multiplexer unit which
is controlled via ACPI methods.

4 combinations of systems typically exist - with 2 ACPI methods.
Intel/ATI - Lenovo W500/T500 - use ATPX ACPI method
ATI/ATI - some ASUS - use ATPX ACPI Method
Intel/Nvidia - - use _DSM ACPI method
Nvidia/Nvidia -  - use _DSM ACPI method.

TODO:
This patch adds support for the ATPX method and initial bits
for the _DSM methods that need to written by someone with
access to the hardware.
Add a proper non-debugfs interface - need to get some proper
testing first.

v2: add power up/down support for both devices
on W500 puts i915/radeon into D3 and cuts power to radeon.

v3: redo probing methods, no DMI list, drm devices call to
register with switcheroo, it tries to find an ATPX method on
any device and once there is two devices + ATPX it inits the
switcher.

v4: ATPX msg handling using buffers - should work on more machines

v5: rearchitect after more mjg59 discussion - move ATPX handling to
    radeon driver.

v6: add file headers + initial nouveau bits (to be filled out).

v7: merge delayed switcher code.

v8: avoid suspend/resume of gpu that is off

v9: rearchitect - mjg59 is always right. - move all ATPX code to
radeon, should allow simpler DSM also proper ATRM handling

v10: add ATRM support for radeon BIOS, add mutex to lock vgasr_priv

v11: fix bug in resuming Intel for 2nd time.

v12: start fixing up nvidia code blindly.

v13: blindly guess at finishing nvidia code

v14: remove radeon audio hacks - fix up intel resume more like upstream

v15: clean up printks + remove unnecessary igd/dis pointers

mount debugfs

/sys/kernel/debug/vgaswitcheroo/switch - should exist if ATPX detected
 + 2 cards.

DIS - immediate change to discrete
IGD - immediate change to IGD
DDIS - delayed change to discrete
DIGD - delayed change to IGD
ON - turn on not in use
OFF - turn off not in use

Tested on W500 (Intel/ATI) and T500 (Intel/ATI)

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 2307f98349f7..42ca07f04a21 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -35,6 +35,7 @@
 #include "i915_drv.h"
 #include "i915_trace.h"
 #include <linux/vgaarb.h>
+#include <linux/vga_switcheroo.h>
 
 /* Really want an OS-independent resettable timer.  Would like to have
  * this loop run for (eg) 3 sec, but have the timer reset every time
@@ -1199,6 +1200,32 @@ static unsigned int i915_vga_set_decode(void *cookie, bool state)
                 return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
 }
 
+static void i915_switcheroo_set_state(struct pci_dev *pdev, enum vga_switcheroo_state state)
+{
+        struct drm_device *dev = pci_get_drvdata(pdev);
+        pm_message_t pmm = { .event = PM_EVENT_SUSPEND };
+        if (state == VGA_SWITCHEROO_ON) {
+                printk(KERN_INFO "i915: switched off\n");
+                /* i915 resume handler doesn't set to D0 */
+                pci_set_power_state(dev->pdev, PCI_D0);
+                i915_resume(dev);
+        } else {
+                printk(KERN_ERR "i915: switched off\n");
+                i915_suspend(dev, pmm);
+        }
+}
+
+static bool i915_switcheroo_can_switch(struct pci_dev *pdev)
+{
+        struct drm_device *dev = pci_get_drvdata(pdev);
+        bool can_switch;
+
+        spin_lock(&dev->count_lock);
+        can_switch = (dev->open_count == 0);
+        spin_unlock(&dev->count_lock);
+        return can_switch;
+}
+
 static int i915_load_modeset_init(struct drm_device *dev,
                                   unsigned long prealloc_start,
                                   unsigned long prealloc_size,
@@ -1260,6 +1287,12 @@ static int i915_load_modeset_init(struct drm_device *dev,
         if (ret)
                 goto destroy_ringbuffer;
 
+        ret = vga_switcheroo_register_client(dev->pdev,
+                                             i915_switcheroo_set_state,
+                                             i915_switcheroo_can_switch);
+        if (ret)
+                goto destroy_ringbuffer;
+
         intel_modeset_init(dev);
 
         ret = drm_irq_install(dev);
@@ -1544,6 +1577,7 @@ int i915_driver_unload(struct drm_device *dev)
                         dev_priv->child_dev_num = 0;
                 }
                 drm_irq_uninstall(dev);
+                vga_switcheroo_unregister_client(dev->pdev);
                 vga_client_register(dev->pdev, NULL, NULL, NULL);
         }
 
@@ -1611,6 +1645,7 @@ void i915_driver_lastclose(struct drm_device * dev)
 
         if (!dev_priv || drm_core_check_feature(dev, DRIVER_MODESET)) {
                 drm_fb_helper_restore();
+                vga_switcheroo_process_delayed_switch();
                 return;
         }