This patch refactors the switch statement in handle_cmd_completion() by
creating a separate function for each branch, named 'xhci_handle_cmd_<type>'.

Other changes introduced by this patch are:

- Renaming the already existed functions by adding the prefix
  'xhci_handle_cmd_' for consistency. Also, for handle_stopped_endpoint()
  the order of arguments was changed too, so that the prototype of
  'xhci_handle_cmd_' be similar and easy to follow.
- Additional local variables were added, such as cmd_trb, cmd_comp_code,
  cmd_type, add_flags and drop_flags, and the label 'update_ring',
  mainly to reduce code dublication and line length.
- The variable ep_ring, that was assigned in the case TRB_CONFIG_EP
  but never used, was removed.

Signed-off-by: Xenia Ragiadakou <burzalod...@gmail.com>
---

Differences from version 1:

Create separate functions for each switch case branch, instead of a single
function holding the entire switch

 drivers/usb/host/xhci-ring.c | 310 ++++++++++++++++++++++++++-----------------
 1 file changed, 185 insertions(+), 125 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index ddbda35..bc9ce03 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -755,8 +755,8 @@ static void xhci_giveback_urb_in_irq(struct xhci_hcd *xhci,
  *  2. Otherwise, we turn all the TRBs in the TD into No-op TRBs (with the 
chain
  *     bit cleared) so that the HW will skip over them.
  */
-static void handle_stopped_endpoint(struct xhci_hcd *xhci,
-               union xhci_trb *trb, struct xhci_event_cmd *event)
+static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, union xhci_trb *trb)
 {
        unsigned int slot_id;
        unsigned int ep_index;
@@ -1063,9 +1063,8 @@ static void update_ring_for_set_deq_completion(struct 
xhci_hcd *xhci,
  * endpoint doorbell to restart the ring, but only if there aren't more
  * cancellations pending.
  */
-static void handle_set_deq_completion(struct xhci_hcd *xhci,
-               struct xhci_event_cmd *event,
-               union xhci_trb *trb)
+static void xhci_handle_cmd_set_deq(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, union xhci_trb *trb)
 {
        unsigned int slot_id;
        unsigned int ep_index;
@@ -1157,9 +1156,8 @@ static void handle_set_deq_completion(struct xhci_hcd 
*xhci,
        ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
 }
 
-static void handle_reset_ep_completion(struct xhci_hcd *xhci,
-               struct xhci_event_cmd *event,
-               union xhci_trb *trb)
+static void xhci_handle_cmd_reset_ep(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, union xhci_trb *trb)
 {
        int slot_id;
        unsigned int ep_index;
@@ -1372,21 +1370,160 @@ static int handle_stopped_cmd_ring(struct xhci_hcd 
*xhci,
        return cur_trb_is_good;
 }
 
-static void handle_cmd_completion(struct xhci_hcd *xhci,
+static void xhci_handle_cmd_enable_slot(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+       int slot_id;
+
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       if (cmd_comp_code == COMP_SUCCESS)
+               xhci->slot_id = slot_id;
+       else
+               xhci->slot_id = 0;
+       complete(&xhci->addr_dev);
+}
+
+static void xhci_handle_cmd_disable_slot(struct xhci_hcd *xhci,
                struct xhci_event_cmd *event)
 {
-       int slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
-       u64 cmd_dma;
-       dma_addr_t cmd_dequeue_dma;
-       struct xhci_input_control_ctx *ctrl_ctx;
+       int slot_id;
        struct xhci_virt_device *virt_dev;
+
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       virt_dev = xhci->devs[slot_id];
+       if (!virt_dev)
+               return;
+       if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
+               /* Delete default control endpoint resources */
+               xhci_free_device_endpoint_resources(xhci, virt_dev, true);
+       xhci_free_virt_device(xhci, slot_id);
+}
+
+static void xhci_handle_cmd_config_ep(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+       int slot_id;
+       struct xhci_virt_device *virt_dev;
+       struct xhci_input_control_ctx *ctrl_ctx;
        unsigned int ep_index;
-       struct xhci_ring *ep_ring;
        unsigned int ep_state;
+       u32 add_flags, drop_flags;
+
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       virt_dev = xhci->devs[slot_id];
+       if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
+               return;
+       /*
+        * Configure endpoint commands can come from the USB core
+        * configuration or alt setting changes, or because the HW
+        * needed an extra configure endpoint command after a reset
+        * endpoint command or streams were being configured.
+        * If the command was for a halted endpoint, the xHCI driver
+        * is not waiting on the configure endpoint command.
+        */
+       ctrl_ctx = xhci_get_input_control_ctx(xhci, virt_dev->in_ctx);
+       if (!ctrl_ctx) {
+               xhci_warn(xhci, "Could not get input context, bad type.\n");
+               return;
+       }
+       add_flags = le32_to_cpu(ctrl_ctx->add_flags);
+       drop_flags = le32_to_cpu(ctrl_ctx->drop_flags);
+       /* Input ctx add_flags are the endpoint index plus one */
+       ep_index = xhci_last_valid_endpoint(add_flags) - 1;
+       /* A usb_set_interface() call directly after clearing a halted
+        * condition may race on this quirky hardware.  Not worth
+        * worrying about, since this is prototype hardware.  Not sure
+        * if this will work for streams, but streams support was
+        * untested on this prototype.
+        */
+       if (xhci->quirks & XHCI_RESET_EP_QUIRK &&
+                       ep_index != (unsigned int) -1 &&
+                       add_flags - SLOT_FLAG == drop_flags) {
+               ep_state = virt_dev->eps[ep_index].ep_state;
+               if (!(ep_state & EP_HALTED))
+                       goto bandwidth_change;
+               xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
+                               "Completed config ep cmd - "
+                               "last ep index = %d, state = %d",
+                               ep_index, ep_state);
+               /* Clear internal halted state and restart ring(s) */
+               virt_dev->eps[ep_index].ep_state &= ~EP_HALTED;
+               ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
+               return;
+       }
+bandwidth_change:
+       xhci_dbg_trace(xhci,  trace_xhci_dbg_context_change,
+                       "Completed config ep cmd");
+       virt_dev->cmd_status = cmd_comp_code;
+       complete(&virt_dev->cmd_completion);
+}
+
+static void xhci_handle_cmd_eval_ctx(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+       int slot_id;
+       struct xhci_virt_device *virt_dev;
+
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       virt_dev = xhci->devs[slot_id];
+       if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
+               return;
+       virt_dev->cmd_status = cmd_comp_code;
+       complete(&virt_dev->cmd_completion);
+}
+
+static void xhci_handle_cmd_addr_dev(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event, u32 cmd_comp_code)
+{
+       int slot_id;
+
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       xhci->devs[slot_id]->cmd_status = cmd_comp_code;
+       complete(&xhci->addr_dev);
+}
+
+static void xhci_handle_cmd_reset_dev(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event)
+{
+       int slot_id;
+       struct xhci_virt_device *virt_dev;
+
+       xhci_dbg(xhci, "Completed reset device command.\n");
+       slot_id = TRB_TO_SLOT_ID(le32_to_cpu(event->flags));
+       virt_dev = xhci->devs[slot_id];
+       if (virt_dev)
+               handle_cmd_in_cmd_wait_list(xhci, virt_dev, event);
+       else
+               xhci_warn(xhci, "Reset device command completion "
+                               "for disabled slot %u\n", slot_id);
+}
+
+static void xhci_handle_cmd_nec_get_fw(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event)
+{
+       if (!(xhci->quirks & XHCI_NEC_HOST)) {
+               xhci->error_bitmask |= 1 << 6;
+               return;
+       }
+       xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
+                       "NEC firmware version %2x.%02x",
+                        NEC_FW_MAJOR(le32_to_cpu(event->status)),
+                        NEC_FW_MINOR(le32_to_cpu(event->status)));
+}
+
+static void handle_cmd_completion(struct xhci_hcd *xhci,
+               struct xhci_event_cmd *event)
+{
+       u64 cmd_dma;
+       dma_addr_t cmd_dequeue_dma;
+       union xhci_trb *cmd_trb;
+       u32 cmd_comp_code;
+       u32 cmd_type;
 
        cmd_dma = le64_to_cpu(event->cmd_trb);
+       cmd_trb = xhci->cmd_ring->dequeue;
        cmd_dequeue_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
-                       xhci->cmd_ring->dequeue);
+                                               cmd_trb);
        /* Is the command ring deq ptr out of sync with the deq seg ptr? */
        if (cmd_dequeue_dma == 0) {
                xhci->error_bitmask |= 1 << 4;
@@ -1398,142 +1535,65 @@ static void handle_cmd_completion(struct xhci_hcd 
*xhci,
                return;
        }
 
-       trace_xhci_cmd_completion(&xhci->cmd_ring->dequeue->generic,
-                                       (struct xhci_generic_trb *) event);
+       trace_xhci_cmd_completion(cmd_trb, (struct xhci_generic_trb *) event);
 
-       if ((GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_CMD_ABORT) ||
-               (GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_CMD_STOP)) {
+       cmd_comp_code = GET_COMP_CODE(le32_to_cpu(event->status));
+       if (cmd_comp_code == COMP_CMD_ABORT || cmd_comp_code == COMP_CMD_STOP) {
                /* If the return value is 0, we think the trb pointed by
                 * command ring dequeue pointer is a good trb. The good
                 * trb means we don't want to cancel the trb, but it have
                 * been stopped by host. So we should handle it normally.
                 * Otherwise, driver should invoke inc_deq() and return.
                 */
-               if (handle_stopped_cmd_ring(xhci,
-                               GET_COMP_CODE(le32_to_cpu(event->status)))) {
-                       inc_deq(xhci, xhci->cmd_ring);
-                       return;
-               }
+               if (handle_stopped_cmd_ring(xhci, cmd_comp_code))
+                       goto update_ring;
        }
 
-       switch (le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3])
-               & TRB_TYPE_BITMASK) {
-       case TRB_TYPE(TRB_ENABLE_SLOT):
-               if (GET_COMP_CODE(le32_to_cpu(event->status)) == COMP_SUCCESS)
-                       xhci->slot_id = slot_id;
-               else
-                       xhci->slot_id = 0;
-               complete(&xhci->addr_dev);
+       cmd_type = TRB_FIELD_TO_TYPE(le32_to_cpu(cmd_trb->generic.field[3]));
+
+       switch (cmd_type) {
+
+       case TRB_ENABLE_SLOT:
+               xhci_handle_cmd_enable_slot(xhci, event, cmd_comp_code);
                break;
-       case TRB_TYPE(TRB_DISABLE_SLOT):
-               if (xhci->devs[slot_id]) {
-                       if (xhci->quirks & XHCI_EP_LIMIT_QUIRK)
-                               /* Delete default control endpoint resources */
-                               xhci_free_device_endpoint_resources(xhci,
-                                               xhci->devs[slot_id], true);
-                       xhci_free_virt_device(xhci, slot_id);
-               }
+       case TRB_DISABLE_SLOT:
+               xhci_handle_cmd_disable_slot(xhci, event);
                break;
-       case TRB_TYPE(TRB_CONFIG_EP):
-               virt_dev = xhci->devs[slot_id];
-               if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
-                       break;
-               /*
-                * Configure endpoint commands can come from the USB core
-                * configuration or alt setting changes, or because the HW
-                * needed an extra configure endpoint command after a reset
-                * endpoint command or streams were being configured.
-                * If the command was for a halted endpoint, the xHCI driver
-                * is not waiting on the configure endpoint command.
-                */
-               ctrl_ctx = xhci_get_input_control_ctx(xhci,
-                               virt_dev->in_ctx);
-               if (!ctrl_ctx) {
-                       xhci_warn(xhci, "Could not get input context, bad 
type.\n");
-                       break;
-               }
-               /* Input ctx add_flags are the endpoint index plus one */
-               ep_index = 
xhci_last_valid_endpoint(le32_to_cpu(ctrl_ctx->add_flags)) - 1;
-               /* A usb_set_interface() call directly after clearing a halted
-                * condition may race on this quirky hardware.  Not worth
-                * worrying about, since this is prototype hardware.  Not sure
-                * if this will work for streams, but streams support was
-                * untested on this prototype.
-                */
-               if (xhci->quirks & XHCI_RESET_EP_QUIRK &&
-                               ep_index != (unsigned int) -1 &&
-                   le32_to_cpu(ctrl_ctx->add_flags) - SLOT_FLAG ==
-                   le32_to_cpu(ctrl_ctx->drop_flags)) {
-                       ep_ring = xhci->devs[slot_id]->eps[ep_index].ring;
-                       ep_state = xhci->devs[slot_id]->eps[ep_index].ep_state;
-                       if (!(ep_state & EP_HALTED))
-                               goto bandwidth_change;
-                       xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
-                                       "Completed config ep cmd - "
-                                       "last ep index = %d, state = %d",
-                                       ep_index, ep_state);
-                       /* Clear internal halted state and restart ring(s) */
-                       xhci->devs[slot_id]->eps[ep_index].ep_state &=
-                               ~EP_HALTED;
-                       ring_doorbell_for_active_rings(xhci, slot_id, ep_index);
-                       break;
-               }
-bandwidth_change:
-               xhci_dbg_trace(xhci,  trace_xhci_dbg_context_change,
-                               "Completed config ep cmd");
-               xhci->devs[slot_id]->cmd_status =
-                       GET_COMP_CODE(le32_to_cpu(event->status));
-               complete(&xhci->devs[slot_id]->cmd_completion);
+       case TRB_CONFIG_EP:
+               xhci_handle_cmd_config_ep(xhci, event, cmd_comp_code);
                break;
-       case TRB_TYPE(TRB_EVAL_CONTEXT):
-               virt_dev = xhci->devs[slot_id];
-               if (handle_cmd_in_cmd_wait_list(xhci, virt_dev, event))
-                       break;
-               xhci->devs[slot_id]->cmd_status = 
GET_COMP_CODE(le32_to_cpu(event->status));
-               complete(&xhci->devs[slot_id]->cmd_completion);
+       case TRB_EVAL_CONTEXT:
+               xhci_handle_cmd_eval_ctx(xhci, event, cmd_comp_code);
                break;
-       case TRB_TYPE(TRB_ADDR_DEV):
-               xhci->devs[slot_id]->cmd_status = 
GET_COMP_CODE(le32_to_cpu(event->status));
-               complete(&xhci->addr_dev);
+       case TRB_ADDR_DEV:
+               xhci_handle_cmd_addr_dev(xhci, event, cmd_comp_code);
                break;
-       case TRB_TYPE(TRB_STOP_RING):
-               handle_stopped_endpoint(xhci, xhci->cmd_ring->dequeue, event);
+       case TRB_STOP_RING:
+               xhci_handle_cmd_stop_ep(xhci, event, cmd_trb);
                break;
-       case TRB_TYPE(TRB_SET_DEQ):
-               handle_set_deq_completion(xhci, event, xhci->cmd_ring->dequeue);
+       case TRB_SET_DEQ:
+               xhci_handle_cmd_set_deq(xhci, event, cmd_trb);
                break;
-       case TRB_TYPE(TRB_CMD_NOOP):
+       case TRB_CMD_NOOP:
                break;
-       case TRB_TYPE(TRB_RESET_EP):
-               handle_reset_ep_completion(xhci, event, 
xhci->cmd_ring->dequeue);
+       case TRB_RESET_EP:
+               xhci_handle_cmd_reset_ep(xhci, event, cmd_trb);
                break;
-       case TRB_TYPE(TRB_RESET_DEV):
-               xhci_dbg(xhci, "Completed reset device command.\n");
-               slot_id = TRB_TO_SLOT_ID(
-                       le32_to_cpu(xhci->cmd_ring->dequeue->generic.field[3]));
-               virt_dev = xhci->devs[slot_id];
-               if (virt_dev)
-                       handle_cmd_in_cmd_wait_list(xhci, virt_dev, event);
-               else
-                       xhci_warn(xhci, "Reset device command completion "
-                                       "for disabled slot %u\n", slot_id);
+       case TRB_RESET_DEV:
+               xhci_handle_cmd_reset_dev(xhci, event);
                break;
-       case TRB_TYPE(TRB_NEC_GET_FW):
-               if (!(xhci->quirks & XHCI_NEC_HOST)) {
-                       xhci->error_bitmask |= 1 << 6;
-                       break;
-               }
-               xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
-                       "NEC firmware version %2x.%02x",
-                        NEC_FW_MAJOR(le32_to_cpu(event->status)),
-                        NEC_FW_MINOR(le32_to_cpu(event->status)));
+       case TRB_NEC_GET_FW:
+               xhci_handle_cmd_nec_get_fw(xhci, event);
                break;
        default:
                /* Skip over unknown commands on the event ring */
                xhci->error_bitmask |= 1 << 6;
                break;
        }
+
+update_ring:
        inc_deq(xhci, xhci->cmd_ring);
+       return;
 }
 
 static void handle_vendor_event(struct xhci_hcd *xhci,
-- 
1.8.3.4

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