Re: [PATCH 1/1] usb: xhci: clean up error_bitmask usage

From: Mathias Nyman
Date: Wed Oct 19 2016 - 02:52:51 EST


Hi

On 19.10.2016 03:53, Lu Baolu wrote:
In xhci_handle_event(), when errors are detected, driver always sets
a bit in error_bitmask (one member of the xhci private driver data).
That means users have to retrieve and decode the value of error_bitmask
in xhci private driver data if they want to know whether those erros
ever happened in xhci_handle_event(). Otherwise, those errors are just
ignored silently.

This patch cleans up this by replacing the setting of error_bitmask
with the kernel print functions, so that users can easily check and
report the errors happened in xhci_handle_event().

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Nice to get this cleaned out. I think the error_bitmask was something
used during driver development but has no function anymore.

A few minor comments below

---
drivers/usb/host/xhci-ring.c | 42 +++++++++++++++++++-----------------------
drivers/usb/host/xhci.h | 2 --
2 files changed, 19 insertions(+), 25 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 797137e..a460423 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1183,7 +1183,7 @@ 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;
+ xhci_warn(xhci, "WARN NEC_GET_FW command on non-NEC host\n");
return;
}
xhci_dbg_trace(xhci, trace_xhci_dbg_quirks,
@@ -1325,14 +1325,13 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
cmd_trb = xhci->cmd_ring->dequeue;
cmd_dequeue_dma = xhci_trb_virt_to_dma(xhci->cmd_ring->deq_seg,
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;
- return;
- }
- /* Does the DMA address match our internal dequeue pointer address? */
- if (cmd_dma != (u64) cmd_dequeue_dma) {
- xhci->error_bitmask |= 1 << 5;
+ /*
+ * Check whether the completion event is for our internal kept
+ * command.
+ */
+ if (!cmd_dequeue_dma || cmd_dma != (u64)cmd_dequeue_dma) {
+ xhci_warn(xhci,
+ "ERROR mismatched command completion event\n");
return;
}

@@ -1418,7 +1417,7 @@ static void handle_cmd_completion(struct xhci_hcd *xhci,
break;
default:
/* Skip over unknown commands on the event ring */
- xhci->error_bitmask |= 1 << 6;
+ xhci_info(xhci, "INFO unknown command type %d\n", cmd_type);
break;
}

@@ -1521,7 +1520,7 @@ static void handle_port_status(struct xhci_hcd *xhci,
/* Port status change events always have a successful completion code */
if (GET_COMP_CODE(le32_to_cpu(event->generic.field[2])) != COMP_SUCCESS) {
xhci_warn(xhci, "WARN: xHC returned failed port status event\n");
- xhci->error_bitmask |= 1 << 8;
+ return;

I don't think we should return here, it will mess up the event ring dequeue pointer.
And a non-expected completion code here should not prevent us from working normally

}
port_id = GET_PORT_ID(le32_to_cpu(event->generic.field[0]));
xhci_dbg(xhci, "Port Status Change Event for port %d\n", port_id);
@@ -2642,20 +2641,18 @@ static int xhci_handle_event(struct xhci_hcd *xhci)
{
union xhci_trb *event;
int update_ptrs = 1;
- int ret;

+ /* Event ring hasn't been allocated yet. */
if (!xhci->event_ring || !xhci->event_ring->dequeue) {
- xhci->error_bitmask |= 1 << 1;
- return 0;
+ xhci_err(xhci, "ERROR event ring not ready\n");
+ return -ENOMEM;
}

event = xhci->event_ring->dequeue;
/* Does the HC or OS own the TRB? */
if ((le32_to_cpu(event->event_cmd.flags) & TRB_CYCLE) !=
- xhci->event_ring->cycle_state) {
- xhci->error_bitmask |= 1 << 2;
+ xhci->event_ring->cycle_state)
return 0;
- }

/*
* Barrier between reading the TRB_CYCLE (valid) flag above and any
@@ -2663,7 +2660,7 @@ static int xhci_handle_event(struct xhci_hcd *xhci)
*/
rmb();
/* FIXME: Handle more event types. */
- switch ((le32_to_cpu(event->event_cmd.flags) & TRB_TYPE_BITMASK)) {
+ switch (le32_to_cpu(event->event_cmd.flags) & TRB_TYPE_BITMASK) {
case TRB_TYPE(TRB_COMPLETION):
handle_cmd_completion(xhci, &event->event_cmd);
break;
@@ -2672,10 +2669,7 @@ static int xhci_handle_event(struct xhci_hcd *xhci)
update_ptrs = 0;
break;
case TRB_TYPE(TRB_TRANSFER):
- ret = handle_tx_event(xhci, &event->trans_event);
- if (ret < 0)
- xhci->error_bitmask |= 1 << 9;
- else
+ if (!handle_tx_event(xhci, &event->trans_event))
update_ptrs = 0;

had to check this, it works because handle_tx_event() doesn't return positive values.

break;
case TRB_TYPE(TRB_DEV_NOTE):
@@ -2686,7 +2680,9 @@ static int xhci_handle_event(struct xhci_hcd *xhci)
TRB_TYPE(48))
handle_vendor_event(xhci, event);
else
- xhci->error_bitmask |= 1 << 3;
+ xhci_warn(xhci, "ERROR unknown event type %d\n",
+ le32_to_cpu(event->event_cmd.flags) &
+ TRB_TYPE_BITMASK);

This trb type is still shifted 10 bits when printing it out.
There are not yet any proper helpers or macros for this it seems

-Mathias