* 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.
*/
/**
* (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.
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
/* 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)
/**
* 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) {
}
vgasr_priv.handler = handler;
+ vgasr_priv.handler_flags = handler_flags;
if (vga_switcheroo_ready()) {
pr_info("enabled\n");
vga_switcheroo_enable();
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,
}
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
*
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;
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;
}
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;
projects / cascardo / linux.git / blobdiff