target/linux/pistachio/patches-4.9/101-dmaengine-img-mdc-Handle-early-status-read.patch

   1 From a2dd154377c9aa6ddda00d39b8c7c334e4fa16ff Mon Sep 17 00:00:00 2001
   2 From: Damien Horsley <damien.horsley@imgtec.com>
   3 Date: Tue, 22 Mar 2016 12:46:09 +0000
   4 Subject: dmaengine: img-mdc: Handle early status read
   5
   6 It is possible that mdc_tx_status may be called before the first
   7 node has been read from memory.
   8
   9 In this case, the residue value stored in the register is undefined.
  10 Return the transfer size instead.
  11
  12 Signed-off-by: Damien Horsley <damien.horsley@imgtec.com>
  13 ---
  14  drivers/dma/img-mdc-dma.c | 40 ++++++++++++++++++++++++----------------
  15  1 file changed, 24 insertions(+), 16 deletions(-)
  16
  17 diff --git a/drivers/dma/img-mdc-dma.c b/drivers/dma/img-mdc-dma.c
  18 index 624f1e1..0216e2c 100644
  19 --- a/drivers/dma/img-mdc-dma.c
  20 +++ b/drivers/dma/img-mdc-dma.c
  21 @@ -623,25 +623,33 @@ static enum dma_status mdc_tx_status(struct dma_chan *chan,
  22                         (MDC_CMDS_PROCESSED_CMDS_DONE_MASK + 1);
  23
  24                 /*
  25 -                * If the command loaded event hasn't been processed yet, then
  26 -                * the difference above includes an extra command.
  27 +                * If the first node has not yet been read from memory,
  28 +                * the residue register value is undefined
  29                  */
  30 -               if (!mdesc->cmd_loaded)
  31 -                       cmds--;
  32 -               else
  33 -                       cmds += mdesc->list_cmds_done;
  34 -
  35 -               bytes = mdesc->list_xfer_size;
  36 -               ldesc = mdesc->list;
  37 -               for (i = 0; i < cmds; i++) {
  38 -                       bytes -= ldesc->xfer_size + 1;
  39 -                       ldesc = ldesc->next_desc;
  40 -               }
  41 -               if (ldesc) {
  42 -                       if (residue != MDC_TRANSFER_SIZE_MASK)
  43 -                               bytes -= ldesc->xfer_size - residue;
  44 +               if (!mdesc->cmd_loaded && !cmds) {
  45 +                       bytes = mdesc->list_xfer_size;
  46 +               } else {
  47 +                       /*
  48 +                        * If the command loaded event hasn't been processed yet, then
  49 +                        * the difference above includes an extra command.
  50 +                        */
  51 +                       if (!mdesc->cmd_loaded)
  52 +                               cmds--;
  53                         else
  54 +                               cmds += mdesc->list_cmds_done;
  55 +
  56 +                       bytes = mdesc->list_xfer_size;
  57 +                       ldesc = mdesc->list;
  58 +                       for (i = 0; i < cmds; i++) {
  59                                 bytes -= ldesc->xfer_size + 1;
  60 +                               ldesc = ldesc->next_desc;
  61 +                       }
  62 +                       if (ldesc) {
  63 +                               if (residue != MDC_TRANSFER_SIZE_MASK)
  64 +                                       bytes -= ldesc->xfer_size - residue;
  65 +                               else
  66 +                                       bytes -= ldesc->xfer_size + 1;
  67 +                       }
  68                 }
  69         }
  70         spin_unlock_irqrestore(&mchan->vc.lock, flags);
  71 --
  72 2.7.4
  73