On 9/12/23 05:59, Venkatesh Yadav Abbarapu wrote:
The xhci host controller driver trying to queue the URB's and it is
getting halted at the endpoint, thereby hitting the BUG_ON's.
Mostly these kind of random issues are seen on faulty boards.
Removing these BUG_ON's from the U-Boot xhci code, as in Linux kernel
xhci code BUG_ON/BUG's are removed entirely.
Please also note, that BUG_ON() is not recommended any more in the Linux
kernel.
Similar issue has been observed on TI AM437x board and they created a patch
in Linux kernel as below
https://patches.linaro.org/project/linux-usb/patch/1390250711-25840-1-git-send-email-ba...@ti.com/

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbar...@amd.com>
---
  drivers/usb/host/xhci-mem.c  | 17 -----------------
  drivers/usb/host/xhci-ring.c | 31 +++++++------------------------
  drivers/usb/host/xhci.c      |  6 ------
  include/usb/xhci.h           |  2 +-
  4 files changed, 8 insertions(+), 48 deletions(-)

diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
index 72b7530626..0efb4bd7ba 100644
--- a/drivers/usb/host/xhci-mem.c
+++ b/drivers/usb/host/xhci-mem.c
@@ -36,8 +36,6 @@
   */
  void xhci_flush_cache(uintptr_t addr, u32 len)
  {
-       BUG_ON((void *)addr == NULL || len == 0);
-
        flush_dcache_range(addr & ~(CACHELINE_SIZE - 1),
                                ALIGN(addr + len, CACHELINE_SIZE));
  }
@@ -51,8 +49,6 @@ void xhci_flush_cache(uintptr_t addr, u32 len)
   */
  void xhci_inval_cache(uintptr_t addr, u32 len)
  {
-       BUG_ON((void *)addr == NULL || len == 0);
-
        invalidate_dcache_range(addr & ~(CACHELINE_SIZE - 1),
                                ALIGN(addr + len, CACHELINE_SIZE));
  }
@@ -84,8 +80,6 @@ static void xhci_ring_free(struct xhci_ctrl *ctrl, struct 
xhci_ring *ring)
        struct xhci_segment *seg;
        struct xhci_segment *first_seg;
- BUG_ON(!ring);
-
        first_seg = ring->first_seg;
        seg = first_seg->next;
        while (seg != first_seg) {
@@ -210,7 +204,6 @@ static void *xhci_malloc(unsigned int size)
        size_t cacheline_size = max(XHCI_ALIGNMENT, CACHELINE_SIZE);
ptr = memalign(cacheline_size, ALIGN(size, cacheline_size));
-       BUG_ON(!ptr);
        memset(ptr, '\0', size);
xhci_flush_cache((uintptr_t)ptr, size);
@@ -291,7 +284,6 @@ static struct xhci_segment *xhci_segment_alloc(struct 
xhci_ctrl *ctrl)
        struct xhci_segment *seg;
seg = malloc(sizeof(struct xhci_segment));
-       BUG_ON(!seg);
seg->trbs = xhci_malloc(SEGMENT_SIZE);
        seg->dma = xhci_dma_map(ctrl, seg->trbs, SEGMENT_SIZE);
@@ -323,13 +315,11 @@ struct xhci_ring *xhci_ring_alloc(struct xhci_ctrl *ctrl, 
unsigned int num_segs,
        struct xhci_segment *prev;
ring = malloc(sizeof(struct xhci_ring));
-       BUG_ON(!ring);
if (num_segs == 0)
                return ring;
ring->first_seg = xhci_segment_alloc(ctrl);
-       BUG_ON(!ring->first_seg);
num_segs--; @@ -338,7 +328,6 @@ struct xhci_ring *xhci_ring_alloc(struct xhci_ctrl *ctrl, unsigned int num_segs,
                struct xhci_segment *next;
next = xhci_segment_alloc(ctrl);
-               BUG_ON(!next);
xhci_link_segments(ctrl, prev, next, link_trbs); @@ -399,7 +388,6 @@ static int xhci_scratchpad_alloc(struct xhci_ctrl *ctrl)
                        break;
                page_size = page_size >> 1;
        }
-       BUG_ON(i == 16);
ctrl->page_size = 1 << (i + 12);
        buf = memalign(ctrl->page_size, num_sp * ctrl->page_size);
@@ -444,9 +432,7 @@ static struct xhci_container_ctx
        struct xhci_container_ctx *ctx;
ctx = malloc(sizeof(struct xhci_container_ctx));
-       BUG_ON(!ctx);
- BUG_ON((type != XHCI_CTX_TYPE_DEVICE) && (type != XHCI_CTX_TYPE_INPUT));
        ctx->type = type;
        ctx->size = (MAX_EP_CTX_NUM + 1) *
                        CTX_SIZE(xhci_readl(&ctrl->hccr->cr_hccparams));
@@ -638,7 +624,6 @@ int xhci_mem_init(struct xhci_ctrl *ctrl, struct xhci_hccr 
*hccr,
  struct xhci_input_control_ctx
                *xhci_get_input_control_ctx(struct xhci_container_ctx *ctx)
  {
-       BUG_ON(ctx->type != XHCI_CTX_TYPE_INPUT);
        return (struct xhci_input_control_ctx *)ctx->bytes;
  }
@@ -760,8 +745,6 @@ void xhci_setup_addressable_virt_dev(struct xhci_ctrl *ctrl, virt_dev = ctrl->devs[slot_id]; - BUG_ON(!virt_dev);
-
        /* Extract the EP0 and Slot Ctrl */
        ep0_ctx = xhci_get_ep_ctx(ctrl, virt_dev->in_ctx, 0);
        slot_ctx = xhci_get_slot_ctx(ctrl, virt_dev->in_ctx);
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index c8260cbdf9..1bde0b9793 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -244,6 +244,7 @@ static int prepare_ring(struct xhci_ctrl *ctrl, struct 
xhci_ring *ep_ring,
                return -EINVAL;
        case EP_STATE_HALTED:
                puts("WARN halted endpoint, queueing URB anyway.\n");
+               return -EPIPE;
        case EP_STATE_STOPPED:
        case EP_STATE_RUNNING:
                debug("EP STATE RUNNING.\n");
@@ -287,12 +288,15 @@ static int prepare_ring(struct xhci_ctrl *ctrl, struct 
xhci_ring *ep_ring,
   * @param cmd         Command type to enqueue
   * Return: none
   */
-void xhci_queue_command(struct xhci_ctrl *ctrl, dma_addr_t addr, u32 slot_id,
+int xhci_queue_command(struct xhci_ctrl *ctrl, dma_addr_t addr, u32 slot_id,
                        u32 ep_index, trb_type cmd)
  {
        u32 fields[4];
+       int ret;
- BUG_ON(prepare_ring(ctrl, ctrl->cmd_ring, EP_STATE_RUNNING));
+       ret = prepare_ring(ctrl, ctrl->cmd_ring, EP_STATE_RUNNING);
+       if (ret < 0)
+               return ret;
fields[0] = lower_32_bits(addr);
        fields[1] = upper_32_bits(addr);
@@ -311,6 +315,7 @@ void xhci_queue_command(struct xhci_ctrl *ctrl, dma_addr_t 
addr, u32 slot_id,
/* Ring the command ring doorbell */
        xhci_writel(&ctrl->dba->doorbell[0], DB_VALUE_HOST);
+       return 0;
  }
/*
@@ -493,7 +498,6 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, 
trb_type expected)
                return NULL;
printf("XHCI timeout on event type %d... cannot recover.\n", expected);
-       BUG();

There is compilation warning coming from this.

w+../drivers/usb/host/xhci-ring.c: In function ‘xhci_wait_for_event’:
w+../drivers/usb/host/xhci-ring.c:501:1: warning: control reaches end of non-void function [-Wreturn-type]

you should fix it.


diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 1bde0b9793c4..087ef63f86a4 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -498,6 +498,8 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected)
                return NULL;

        printf("XHCI timeout on event type %d... cannot recover.\n", expected);
+
+       return NULL;
 }

Thanks,
Michal

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