diff options
Diffstat (limited to 'drivers/gpu/vga/vga_switcheroo.c')
| -rw-r--r-- | drivers/gpu/vga/vga_switcheroo.c | 119 |
1 files changed, 116 insertions, 3 deletions
diff --git a/drivers/gpu/vga/vga_switcheroo.c b/drivers/gpu/vga/vga_switcheroo.c index 665ab9fd0e01..cbd7c986d926 100644 --- a/drivers/gpu/vga/vga_switcheroo.c +++ b/drivers/gpu/vga/vga_switcheroo.c @@ -74,9 +74,17 @@ * there can thus be up to three clients: Two vga clients (GPUs) and one audio * client (on the discrete GPU). The code is mostly prepared to support * machines with more than two GPUs should they become available. + * * The GPU to which the outputs are currently switched is called the * active client in vga_switcheroo parlance. The GPU not in use is the - * inactive client. + * inactive client. When the inactive client's DRM driver is loaded, + * it will be unable to probe the panel's EDID and hence depends on + * VBIOS to provide its display modes. If the VBIOS modes are bogus or + * if there is no VBIOS at all (which is common on the MacBook Pro), + * a client may alternatively request that the DDC lines are temporarily + * switched to it, provided that the handler supports this. Switching + * only the DDC lines and not the entire output avoids unnecessary + * flickering. */ /** @@ -126,6 +134,10 @@ static DEFINE_MUTEX(vgasr_mutex); * (counting only vga clients, not audio clients) * @clients: list of registered clients * @handler: registered handler + * @handler_flags: flags of registered handler + * @mux_hw_lock: protects mux state + * (in particular while DDC lines are temporarily switched) + * @old_ddc_owner: client to which DDC lines will be switched back on unlock * * vga_switcheroo private data. Currently only one vga_switcheroo instance * per system is supported. @@ -142,6 +154,9 @@ struct vgasr_priv { struct list_head clients; const struct vga_switcheroo_handler *handler; + enum vga_switcheroo_handler_flags_t handler_flags; + struct mutex mux_hw_lock; + int old_ddc_owner; }; #define ID_BIT_AUDIO 0x100 @@ -156,6 +171,7 @@ static void vga_switcheroo_debugfs_fini(struct vgasr_priv *priv); /* only one switcheroo per system */ static struct vgasr_priv vgasr_priv = { .clients = LIST_HEAD_INIT(vgasr_priv.clients), + .mux_hw_lock = __MUTEX_INITIALIZER(vgasr_priv.mux_hw_lock), }; static bool vga_switcheroo_ready(void) @@ -190,13 +206,15 @@ static void vga_switcheroo_enable(void) /** * vga_switcheroo_register_handler() - register handler * @handler: handler callbacks + * @handler_flags: handler flags * * Register handler. Enable vga_switcheroo if two vga clients have already * registered. * * Return: 0 on success, -EINVAL if a handler was already registered. */ -int vga_switcheroo_register_handler(const struct vga_switcheroo_handler *handler) +int vga_switcheroo_register_handler(const struct vga_switcheroo_handler *handler, + enum vga_switcheroo_handler_flags_t handler_flags) { mutex_lock(&vgasr_mutex); if (vgasr_priv.handler) { @@ -205,6 +223,7 @@ int vga_switcheroo_register_handler(const struct vga_switcheroo_handler *handler } vgasr_priv.handler = handler; + vgasr_priv.handler_flags = handler_flags; if (vga_switcheroo_ready()) { pr_info("enabled\n"); vga_switcheroo_enable(); @@ -222,16 +241,33 @@ EXPORT_SYMBOL(vga_switcheroo_register_handler); void vga_switcheroo_unregister_handler(void) { mutex_lock(&vgasr_mutex); + mutex_lock(&vgasr_priv.mux_hw_lock); + vgasr_priv.handler_flags = 0; vgasr_priv.handler = NULL; if (vgasr_priv.active) { pr_info("disabled\n"); vga_switcheroo_debugfs_fini(&vgasr_priv); vgasr_priv.active = false; } + mutex_unlock(&vgasr_priv.mux_hw_lock); mutex_unlock(&vgasr_mutex); } EXPORT_SYMBOL(vga_switcheroo_unregister_handler); +/** + * vga_switcheroo_handler_flags() - obtain handler flags + * + * Helper for clients to obtain the handler flags bitmask. + * + * Return: Handler flags. A value of 0 means that no handler is registered + * or that the handler has no special capabilities. + */ +enum vga_switcheroo_handler_flags_t vga_switcheroo_handler_flags(void) +{ + return vgasr_priv.handler_flags; +} +EXPORT_SYMBOL(vga_switcheroo_handler_flags); + static int register_client(struct pci_dev *pdev, const struct vga_switcheroo_client_ops *ops, enum vga_switcheroo_client_id id, bool active, @@ -413,6 +449,76 @@ void vga_switcheroo_client_fb_set(struct pci_dev *pdev, EXPORT_SYMBOL(vga_switcheroo_client_fb_set); /** + * vga_switcheroo_lock_ddc() - temporarily switch DDC lines to a given client + * @pdev: client pci device + * + * Temporarily switch DDC lines to the client identified by @pdev + * (but leave the outputs otherwise switched to where they are). + * This allows the inactive client to probe EDID. The DDC lines must + * afterwards be switched back by calling vga_switcheroo_unlock_ddc(), + * even if this function returns an error. + * + * Return: Previous DDC owner on success or a negative int on error. + * Specifically, %-ENODEV if no handler has registered or if the handler + * does not support switching the DDC lines. Also, a negative value + * returned by the handler is propagated back to the caller. + * The return value has merely an informational purpose for any caller + * which might be interested in it. It is acceptable to ignore the return + * value and simply rely on the result of the subsequent EDID probe, + * which will be %NULL if DDC switching failed. + */ +int vga_switcheroo_lock_ddc(struct pci_dev *pdev) +{ + enum vga_switcheroo_client_id id; + + mutex_lock(&vgasr_priv.mux_hw_lock); + if (!vgasr_priv.handler || !vgasr_priv.handler->switch_ddc) { + vgasr_priv.old_ddc_owner = -ENODEV; + return -ENODEV; + } + + id = vgasr_priv.handler->get_client_id(pdev); + vgasr_priv.old_ddc_owner = vgasr_priv.handler->switch_ddc(id); + return vgasr_priv.old_ddc_owner; +} +EXPORT_SYMBOL(vga_switcheroo_lock_ddc); + +/** + * vga_switcheroo_unlock_ddc() - switch DDC lines back to previous owner + * @pdev: client pci device + * + * Switch DDC lines back to the previous owner after calling + * vga_switcheroo_lock_ddc(). This must be called even if + * vga_switcheroo_lock_ddc() returned an error. + * + * Return: Previous DDC owner on success (i.e. the client identifier of @pdev) + * or a negative int on error. + * Specifically, %-ENODEV if no handler has registered or if the handler + * does not support switching the DDC lines. Also, a negative value + * returned by the handler is propagated back to the caller. + * Finally, invoking this function without calling vga_switcheroo_lock_ddc() + * first is not allowed and will result in %-EINVAL. + */ +int vga_switcheroo_unlock_ddc(struct pci_dev *pdev) +{ + enum vga_switcheroo_client_id id; + int ret = vgasr_priv.old_ddc_owner; + + if (WARN_ON_ONCE(!mutex_is_locked(&vgasr_priv.mux_hw_lock))) + return -EINVAL; + + if (vgasr_priv.old_ddc_owner >= 0) { + id = vgasr_priv.handler->get_client_id(pdev); + if (vgasr_priv.old_ddc_owner != id) + ret = vgasr_priv.handler->switch_ddc( + vgasr_priv.old_ddc_owner); + } + mutex_unlock(&vgasr_priv.mux_hw_lock); + return ret; +} +EXPORT_SYMBOL(vga_switcheroo_unlock_ddc); + +/** * DOC: Manual switching and manual power control * * In this mode of use, the file /sys/kernel/debug/vgaswitcheroo/switch @@ -549,7 +655,9 @@ static int vga_switchto_stage2(struct vga_switcheroo_client *new_client) console_unlock(); } + mutex_lock(&vgasr_priv.mux_hw_lock); ret = vgasr_priv.handler->switchto(new_client->id); + mutex_unlock(&vgasr_priv.mux_hw_lock); if (ret) return ret; @@ -664,7 +772,9 @@ vga_switcheroo_debugfs_write(struct file *filp, const char __user *ubuf, vgasr_priv.delayed_switch_active = false; if (just_mux) { + mutex_lock(&vgasr_priv.mux_hw_lock); ret = vgasr_priv.handler->switchto(client_id); + mutex_unlock(&vgasr_priv.mux_hw_lock); goto out; } @@ -876,8 +986,11 @@ static int vga_switcheroo_runtime_suspend(struct device *dev) if (ret) return ret; mutex_lock(&vgasr_mutex); - if (vgasr_priv.handler->switchto) + if (vgasr_priv.handler->switchto) { + mutex_lock(&vgasr_priv.mux_hw_lock); vgasr_priv.handler->switchto(VGA_SWITCHEROO_IGD); + mutex_unlock(&vgasr_priv.mux_hw_lock); + } vga_switcheroo_power_switch(pdev, VGA_SWITCHEROO_OFF); mutex_unlock(&vgasr_mutex); return 0; |