kernel/linux.git/include/linux/vga_switcheroo.h, branch v6.12.80

ALSA: hda - Enable runtime PM only for discrete GPU

2018-09-13T15:58:30+00:00

The recent change of vga_switcheroo allowed the runtime PM for HD-audio on AMD GPUs, but this also resulted in a regression. When the HD-audio controller driver gets runtime-suspended, HD-audio link is turned off, and the hotplug notification is ignored. This leads to the inconsistent audio state (the connection isn't notified and ELD is ignored). The best fix would be to implement the proper ELD notification via the audio component, but it's still not ready. As a quick workaround, this patch adds the check of runtime_idle and allows the runtime suspend only when the vga_switcheroo is bound with discrete GPU. That is, a system with a single GPU and APU would be again without runtime PM to keep the HD-audio link for the hotplug notification and ELD read out. Also, the codec->auto_runtime_pm flag is set only for the discrete GPU at the time GPU gets bound via vga_switcheroo (i.e. only dGPU is forcibly runtime-PM enabled), so that APU can still get the ELD notification. For identifying which GPU is bound, a new vga_switcheroo client callback, gpu_bound, is implemented. The vga_switcheroo simply calls this when GPU is bound, and tells whether it's dGPU or APU. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=200945 Fixes: 07f4f97d7b4b ("vga_switcheroo: Use device link for HDA controller") Reported-by: Jian-Hong Pan Tested-by: Jian-Hong Pan Acked-by: Lukas Wunner Signed-off-by: Takashi Iwai

vga_switcheroo: set audio client id according to bound GPU id

2018-07-17T09:12:00+00:00

On modern laptop, there are more and more platforms have two GPUs, and each of them maybe have audio codec for HDMP/DP output. For some dGPU which is no output, audio codec usually is disabled. In currect HDA audio driver, it will set all codec as VGA_SWITCHEROO_DIS, the audio which is binded to UMA will be suspended if user use debugfs to contorl power In HDA driver side, it is difficult to know which GPU the audio has binded to. So set the bound gpu pci dev to vga_switcheroo. if the audio client is not the third registration, audio id will set in vga_switcheroo enable function. if the audio client is the last registration when vga_switcheroo _ready() get true, we should get audio client id from bound GPU directly. Signed-off-by: Jim Qu Reviewed-by: Lukas Wunner Signed-off-by: Takashi Iwai

vga_switcheroo: Use device link for HDA controller

2018-03-13T21:58:09+00:00

Back in 2013, runtime PM for GPUs with integrated HDA controller was introduced with commits 0d69704ae348 ("gpu/vga_switcheroo: add driver control power feature. (v3)") and 246efa4a072f ("snd/hda: add runtime suspend/resume on optimus support (v4)"). Briefly, the idea was that the HDA controller is forced on and off in unison with the GPU. The original code is mostly still in place even though it was never a 100% perfect solution: E.g. on access to the HDA controller, the GPU is powered up via vga_switcheroo_runtime_resume_hdmi_audio() but there are no provisions to keep it resumed until access to the HDA controller has ceased: The GPU autosuspends after 5 seconds, rendering the HDA controller inaccessible. Additionally, a kludge is required when hda_intel.c probes: It has to check whether the GPU is powered down (check_hdmi_disabled()) and defer probing if so. However in the meantime (in v4.10) the driver core has gained a feature called device links which promises to solve such issues in a clean way: It allows us to declare a dependency from the HDA controller (consumer) to the GPU (supplier). The PM core then automagically ensures that the GPU is runtime resumed as long as the HDA controller's ->probe hook is executed and whenever the HDA controller is accessed. By default, the HDA controller has a dependency on its parent, a PCIe Root Port. Adding a device link creates another dependency on its sibling: PCIe Root Port ^ ^ | | | | HDA ===> GPU The device link is not only used for runtime PM, it also guarantees that on system sleep, the HDA controller suspends before the GPU and resumes after the GPU, and on system shutdown the HDA controller's ->shutdown hook is executed before the one of the GPU. It is a complete solution. Using this functionality is as simple as calling device_link_add(), which results in a dmesg entry like this: pci 0000:01:00.1: Linked as a consumer to 0000:01:00.0 The code for the GPU-governed audio power management can thus be removed (except where it's still needed for legacy manual power control). The device link is added in a PCI quirk rather than in hda_intel.c. It is therefore legal for the GPU to runtime suspend to D3cold even if the HDA controller is not bound to a driver or if CONFIG_SND_HDA_INTEL is not enabled, for accesses to the HDA controller will cause the GPU to wake up regardless if they're occurring outside of hda_intel.c (think config space readout via sysfs). Contrary to the previous implementation, the HDA controller's power state is now self-governed, rather than GPU-governed, whereas the GPU's power state is no longer fully self-governed. (The HDA controller needs to runtime suspend before the GPU can.) It is thus crucial that runtime PM is always activated on the HDA controller even if CONFIG_SND_HDA_POWER_SAVE_DEFAULT is set to 0 (which is the default), lest the GPU stays awake. This is achieved by setting the auto_runtime_pm flag on every codec and the AZX_DCAPS_PM_RUNTIME flag on the HDA controller. A side effect is that power consumption might be reduced if the GPU is in use but the HDA controller is not, because the HDA controller is now allowed to go to D3hot. Before, it was forced to stay in D0 as long as the GPU was in use. (There is no reduction in power consumption on my Nvidia GK107, but there might be on other chips.) The code paths for legacy manual power control are adjusted such that runtime PM is disabled during power off, thereby preventing the PM core from resuming the HDA controller. Note that the device link is not only added on vga_switcheroo capable systems, but for *any* GPU with integrated HDA controller. The idea is that the HDA controller streams audio via connectors located on the GPU, so the GPU needs to be on for the HDA controller to do anything useful. This commit implicitly fixes an unbalanced runtime PM ref upon unbind of hda_intel.c: On ->probe, a runtime PM ref was previously released under the condition "azx_has_pm_runtime(chip) || hda->use_vga_switcheroo", but on ->remove a runtime PM ref was only acquired under the first of those conditions. Thus, binding and unbinding the driver twice on a vga_switcheroo capable system caused the runtime PM refcount to drop below zero. The issue is resolved because the AZX_DCAPS_PM_RUNTIME flag is now always set if use_vga_switcheroo is true. For more information on device links please refer to: https://www.kernel.org/doc/html/latest/driver-api/device_link.html Documentation/driver-api/device_link.rst Cc: Dave Airlie Cc: Ben Skeggs Cc: Alex Deucher Cc: Rafael J. Wysocki Acked-by: Bjorn Helgaas Reviewed-by: Takashi Iwai Reviewed-by: Peter Wu Tested-by: Kai Heng Feng # AMD PowerXpress Tested-by: Mike Lothian # AMD PowerXpress Tested-by: Denis Lisov # Nvidia Optimus Tested-by: Peter Wu # Nvidia Optimus Tested-by: Lukas Wunner # MacBook Pro Signed-off-by: Lukas Wunner Link: https://patchwork.freedesktop.org/patch/msgid/51bd38360ff502a8c42b1ebf4405ee1d3f27118d.1520068884.git.lukas@wunner.de

vga_switcheroo: Add helper for deferred probing

2016-05-31T11:15:57+00:00

So far we've got one condition when DRM drivers need to defer probing on a dual GPU system and it's coded separately into each of the relevant drivers. As suggested by Daniel Vetter, deduplicate that code in the drivers and move it to a new vga_switcheroo helper. This yields better encapsulation of concepts and lets us add further checks in a central place. (The existing check pertains to pre-retina MacBook Pros and an additional check is expected to be needed for retinas.) One might be tempted to check deferred probing conditions in vga_switcheroo_register_client(), but this is usually called fairly late during driver load. The GPU is fully brought up and ready for switching at that point. On boot the ->probe hook is potentially called dozens of times until it finally succeeds, and each time we'd repeat bringup and teardown of the GPU, lengthening boot time considerably and cluttering logfiles. A separate helper is therefore needed which can be called right at the beginning of the ->probe hook. Note that amdgpu currently does not call this helper as the AMD GPUs built into MacBook Pros are only supported by radeon so far. v2: This helper could eventually be used by audio clients as well, so rephrase kerneldoc to refer to "client" instead of "GPU" and move the single existing check in an if block specific to PCI_CLASS_DISPLAY_VGA devices. Move documentation on that check from kerneldoc to a comment. (Daniel Vetter) v3: Mandate in kerneldoc that registration of client shall only happen after calling this helper. (Daniel Vetter) v4: Rebase on 412c8f7de011 ("drm/radeon: Return -EPROBE_DEFER when amdkfd not loaded") v5: Some Optimus GPUs use PCI_CLASS_DISPLAY_3D, make sure those are matched as well. (Emil Velikov) v6: The if-condition referring to PCI_BASE_CLASS_DISPLAY may be considered a functional change. Move to a separate commit to keep this a pure refactoring change. (Emil Velikov, Jani Nikula) Cc: Daniel Vetter Cc: Ben Skeggs Cc: Alex Deucher Signed-off-by: Lukas Wunner Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/575885fd440c2b13c3f19ddf44360cfbbff35f50.1464685538.git.lukas@wunner.de

vga_switcheroo: Add support for switching only the DDC

2016-02-09T10:21:07+00:00

Originally by Seth Forshee , 2012-10-04: During graphics driver initialization it's useful to be able to mux only the DDC to the inactive client in order to read the EDID. Add a switch_ddc callback to allow capable handlers to provide this functionality, and add vga_switcheroo_switch_ddc() to allow DRM to mux only the DDC. Modified by Dave Airlie , 2012-12-22: I can't figure out why I didn't like this, but I rewrote this [...] to lock/unlock the ddc lines [...]. I think I'd prefer something like that otherwise the interface got really ugly. Modified by Lukas Wunner , 2015-04 - 2015-10: Change semantics of ->switch_ddc handler callback to return previous DDC owner. Original version tried to determine previous DDC owner with find_active_client() but this fails if the inactive client registers before the active client. Don't lock vgasr_mutex in _lock_ddc() / _unlock_ddc(), it can cause deadlocks because (a) during switch (with vgasr_mutex already held), GPU is woken and probes its outputs, tries to re-acquire vgasr_mutex to lock DDC lines; (b) Likewise during switch, GPU is suspended and calls cancel_delayed_work_sync() to stop output polling, if poll task is running at this moment we may wait forever for it to finish. Instead, lock mux_hw_lock when unregistering the handler because the only reason why we'd want to lock vgasr_mutex in _lock_ddc() / _unlock_ddc() is to block the handler from disappearing while DDC lines are switched. Also acquire mux_hw_lock in stage2 to avoid race condition where reading the EDID and switching happens simultaneously. Likewise on MIGD / MDIS commands and on runtime suspend. v2.1: Overhaul locking, squash commits (Daniel Vetter) v2.2: Readability improvements (Thierry Reding) v2.3: Overhaul locking once more v2.4: Retain semantics of ->switchto handler callback to switch all pins, including DDC (Daniel Vetter) v5: Rename ddc_lock to mux_hw_lock: Since we acquire this both when calling ->switch_ddc and ->switchto, it protects not just access to the DDC lines but to the mux in general. This is in line with the DRM convention to use low-level locks to avoid concurrent hw access (e.g. i2c, dp_aux) which are often called hw_lock (Daniel Vetter) Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115 Tested-by: Lukas Wunner [MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina 15"] Cc: Seth Forshee Cc: Dave Airlie Signed-off-by: Lukas Wunner Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/e81ae9722b84c5ed591805fee3ea6dbf5dc6c4b3.1452525860.git.lukas@wunner.de

vga_switcheroo: Add handler flags infrastructure

2016-02-09T10:21:07+00:00

Allow handlers to declare their capabilities and allow clients to obtain that information. So far we have these use cases: * If the handler is able to switch DDC separately, clients need to probe EDID with drm_get_edid_switcheroo(). We should allow them to detect a capable handler to ensure this function only gets called when needed. * Likewise if the handler is unable to switch AUX separately, the active client needs to communicate link training parameters to the inactive client, which may then skip the AUX handshake and set up its output with these pre-calibrated values (DisplayPort specification v1.1a, section 2.5.3.3). Clients need a way to recognize such a situation. The flags for the radeon_atpx_handler and amdgpu_atpx_handler are initially set to 0, this can later on be amended with handler_flags |= VGA_SWITCHEROO_CAN_SWITCH_DDC; when a ->switch_ddc callback is added. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=88861 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=61115 Tested-by: Lukas Wunner [MBP 9,1 2012 intel IVB + nvidia GK107 pre-retina 15"] Signed-off-by: Lukas Wunner Reviewed-by: Darren Hart Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/2b0d93ed6e511ca09e95e45e0b35627f330fabce.1452525860.git.lukas@wunner.de

vga_switcheroo: Drop client power state VGA_SWITCHEROO_INIT

2015-11-05T01:07:36+00:00

hda_intel.c:azx_probe() defers initialization of an audio controller on the discrete GPU if the GPU is powered off. The power state of the GPU is determined by calling vga_switcheroo_get_client_state(). vga_switcheroo_get_client_state() returns VGA_SWITCHEROO_INIT if vga_switcheroo is not enabled, i.e. if no second GPU or no handler has registered. This can go wrong in the following scenario: - Driver for the integrated GPU is not loaded. - Driver for the discrete GPU registers with vga_switcheroo, uses driver power control to power down the GPU, handler cuts power to the GPU. - Driver for the audio controller gets loaded after the GPU was powered down, calls vga_switcheroo_get_client_state() which returns VGA_SWITCHEROO_INIT instead of VGA_SWITCHEROO_OFF. - Consequence: azx_probe() tries to initialize the audio controller even though the GPU is powered down. The power state VGA_SWITCHEROO_INIT was introduced by c8e9cf7bb240 ("vga_switcheroo: Add a helper function to get the client state"). It is not apparent what its benefit might be. The idea seems to be to initialize the audio controller even if the power state is VGA_SWITCHEROO_OFF (were vga_switcheroo enabled), but as shown above this can fail. Drop VGA_SWITCHEROO_INIT to solve this. Acked-by: Takashi Iwai Signed-off-by: Lukas Wunner Signed-off-by: Dave Airlie

vga_switcheroo: Constify vga_switcheroo_handler

2015-10-20T18:19:29+00:00

vga_switcheroo_client_ops has always been declared const since its introduction with 26ec685ff9d9 ("vga_switcheroo: Introduce struct vga_switcheroo_client_ops"). Do so for vga_switcheroo_handler as well. drivers/gpu/drm/amd/amdgpu/amdgpu.ko: 6 .rodata 00009888 - 19 .data 00001f00 + 19 .data 00001ee0 drivers/gpu/drm/nouveau/nouveau.ko: 6 .rodata 000460b8 17 .data 00018fe0 drivers/gpu/drm/radeon/radeon.ko: - 7 .rodata 00030944 + 7 .rodata 00030964 - 21 .data 0000d6a0 + 21 .data 0000d678 drivers/platform/x86/apple-gmux.ko: - 7 .rodata 00000140 + 7 .rodata 00000160 - 11 .data 000000e0 + 11 .data 000000b8 Cc: Ben Skeggs Cc: Darren Hart Cc: Alex Deucher Signed-off-by: Lukas Wunner Reviewed-by: Christian König . Signed-off-by: Daniel Vetter

vga_switcheroo: Use enum vga_switcheroo_client_id instead of int

2015-10-16T13:50:56+00:00

Signed-off-by: Lukas Wunner Reviewed-by: Alex Deucher Signed-off-by: Daniel Vetter

vga_switcheroo: Use VGA_SWITCHEROO_UNKNOWN_ID instead of -1

2015-10-16T13:50:56+00:00

Signed-off-by: Lukas Wunner Reviewed-by: Alex Deucher Signed-off-by: Daniel Vetter