accel/amdxdna: Fix tail-pointer polling in mailbox_get_msg()

In mailbox_get_msg(), mailbox_reg_read_non_zero() is called to poll for a
non-zero tail pointer. This assumed that a zero value indicates an error.
However, certain corner cases legitimately produce a zero tail pointer.
To handle these cases, remove mailbox_reg_read_non_zero(). The zero tail
pointer will be treated as a valid rewind event.

Reviewed-by: Maciej Falkowski <maciej.falkowski@linux.intel.com>
Signed-off-by: Lizhi Hou <lizhi.hou@amd.com>
Link: https://patch.msgid.link/20251204181603.793824-1-lizhi.hou@amd.com

diff --git a/drivers/accel/amdxdna/amdxdna_mailbox.c b/drivers/accel/amdxdna/amdxdna_mailbox.c
index 858df97cd3fbd48f7c3fedd66eb27eed46e5f908..a60a85ce564cbffc1a16b6c73a958465aef8c0b3 100644 (file)
--- a/drivers/accel/amdxdna/amdxdna_mailbox.c
+++ b/drivers/accel/amdxdna/amdxdna_mailbox.c
@@ -112,22 +112,6 @@ static u32 mailbox_reg_read(struct mailbox_channel *mb_chann, u32 mbox_reg)
        return readl(ringbuf_addr);
 }
 
-static int mailbox_reg_read_non_zero(struct mailbox_channel *mb_chann, u32 mbox_reg, u32 *val)
-{
-       struct xdna_mailbox_res *mb_res = &mb_chann->mb->res;
-       void __iomem *ringbuf_addr = mb_res->mbox_base + mbox_reg;
-       int ret, value;
-
-       /* Poll till value is not zero */
-       ret = readx_poll_timeout(readl, ringbuf_addr, value,
-                                value, 1 /* us */, 100);
-       if (ret < 0)
-               return ret;
-
-       *val = value;
-       return 0;
-}
-
 static inline void
 mailbox_set_headptr(struct mailbox_channel *mb_chann, u32 headptr_val)
 {
@@ -286,8 +270,7 @@ static int mailbox_get_msg(struct mailbox_channel *mb_chann)
        u32 start_addr;
        int ret;
 
-       if (mailbox_reg_read_non_zero(mb_chann, mb_chann->res[CHAN_RES_I2X].mb_tail_ptr_reg, &tail))
-               return -EINVAL;
+       tail = mailbox_get_tailptr(mb_chann, CHAN_RES_I2X);
        head = mb_chann->i2x_head;
        ringbuf_size = mailbox_get_ringbuf_size(mb_chann, CHAN_RES_I2X);
        start_addr = mb_chann->res[CHAN_RES_I2X].rb_start_addr;