+/*
+ * Issue an Evaluate Context command to change the Maximum Exit Latency in the
+ * slot context. If that succeeds, store the new MEL in the xhci_virt_device.
+ */
+static int __maybe_unused xhci_change_max_exit_latency(struct xhci_hcd *xhci,
+ struct usb_device *udev, u16 max_exit_latency)
+{
+ struct xhci_virt_device *virt_dev;
+ struct xhci_command *command;
+ struct xhci_input_control_ctx *ctrl_ctx;
+ struct xhci_slot_ctx *slot_ctx;
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&xhci->lock, flags);
+ if (max_exit_latency == xhci->devs[udev->slot_id]->current_mel) {
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ return 0;
+ }
+
+ /* Attempt to issue an Evaluate Context command to change the MEL. */
+ virt_dev = xhci->devs[udev->slot_id];
+ command = xhci->lpm_command;
+ ctrl_ctx = xhci_get_input_control_ctx(xhci, command->in_ctx);
+ if (!ctrl_ctx) {
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ xhci_warn(xhci, "%s: Could not get input context, bad type.\n",
+ __func__);
+ return -ENOMEM;
+ }
+
+ xhci_slot_copy(xhci, command->in_ctx, virt_dev->out_ctx);
+ spin_unlock_irqrestore(&xhci->lock, flags);
+
+ ctrl_ctx->add_flags |= cpu_to_le32(SLOT_FLAG);
+ slot_ctx = xhci_get_slot_ctx(xhci, command->in_ctx);
+ slot_ctx->dev_info2 &= cpu_to_le32(~((u32) MAX_EXIT));
+ slot_ctx->dev_info2 |= cpu_to_le32(max_exit_latency);
+
+ xhci_dbg(xhci, "Set up evaluate context for LPM MEL change.\n");
+ xhci_dbg(xhci, "Slot %u Input Context:\n", udev->slot_id);
+ xhci_dbg_ctx(xhci, command->in_ctx, 0);
+
+ /* Issue and wait for the evaluate context command. */
+ ret = xhci_configure_endpoint(xhci, udev, command,
+ true, true);
+ xhci_dbg(xhci, "Slot %u Output Context:\n", udev->slot_id);
+ xhci_dbg_ctx(xhci, virt_dev->out_ctx, 0);
+
+ if (!ret) {
+ spin_lock_irqsave(&xhci->lock, flags);
+ virt_dev->current_mel = max_exit_latency;
+ spin_unlock_irqrestore(&xhci->lock, flags);
+ }
+ return ret;
+}
+