The module was initializing completions whenever it was going to wait on
them, and not when the completion was allocated.  This is incorrect
according to the completion docs:

    Calling init_completion() on the same completion object twice is
    most likely a bug [...]

Re-initialization is also unnecessary because the module never uses
complete_all().  Fix this by only ever initializing the completion a
single time, and log if the completions are not consumed as intended
(this is not a fatal problem, but should not go unnoticed).

Signed-off-by: George Hilliard <thirtythreefo...@gmail.com>
---
v2: rewrite of v1
v3: Remove BUG_ON() calls
v4: Indent style fixup

 drivers/staging/mt7621-mmc/sd.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/mt7621-mmc/sd.c b/drivers/staging/mt7621-mmc/sd.c
index e346167754bd..ed63bd3ba6cc 100644
--- a/drivers/staging/mt7621-mmc/sd.c
+++ b/drivers/staging/mt7621-mmc/sd.c
@@ -466,7 +466,11 @@ static unsigned int msdc_command_start(struct msdc_host   
*host,
        host->cmd     = cmd;
        host->cmd_rsp = resp;
 
-       init_completion(&host->cmd_done);
+       // The completion should have been consumed by the previous command
+       // response handler, because the mmc requests should be serialized
+       if(completion_done(&host->cmd_done))
+               dev_err(mmc_dev(host->mmc),
+                       "previous command was not handled\n");
 
        sdr_set_bits(host->base + MSDC_INTEN, wints);
        sdc_send_cmd(rawcmd, cmd->arg);
@@ -488,7 +492,6 @@ static unsigned int msdc_command_resp(struct msdc_host   
*host,
                    MSDC_INT_ACMD19_DONE;
 
        BUG_ON(in_interrupt());
-       //init_completion(&host->cmd_done);
        //sdr_set_bits(host->base + MSDC_INTEN, wints);
 
        spin_unlock(&host->lock);
@@ -670,7 +673,13 @@ static int msdc_do_request(struct mmc_host *mmc, struct 
mmc_request *mrq)
                //msdc_clr_fifo(host);  /* no need */
 
                msdc_dma_on();  /* enable DMA mode first!! */
-               init_completion(&host->xfer_done);
+
+               // The completion should have been consumed by the previous
+               // xfer response handler, because the mmc requests should be
+               // serialized
+               if(completion_done(&host->cmd_done))
+                       dev_err(mmc_dev(host->mmc),
+                               "previous transfer was not handled\n");
 
                /* start the command first*/
                if (msdc_command_start(host, cmd, CMD_TIMEOUT) != 0)
@@ -696,7 +705,6 @@ static int msdc_do_request(struct mmc_host *mmc, struct 
mmc_request *mrq)
                /* for read, the data coming too fast, then CRC error
                 *  start DMA no business with CRC.
                 */
-               //init_completion(&host->xfer_done);
                msdc_dma_start(host);
 
                spin_unlock(&host->lock);
@@ -1687,6 +1695,8 @@ static int msdc_drv_probe(struct platform_device *pdev)
        }
        msdc_init_gpd_bd(host, &host->dma);
 
+       init_completion(&host->cmd_done);
+       init_completion(&host->xfer_done);
        INIT_DELAYED_WORK(&host->card_delaywork, msdc_tasklet_card);
        spin_lock_init(&host->lock);
        msdc_init_hw(host);
-- 
2.21.0

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