target/linux/pistachio/patches-4.14/101-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 --- a/drivers/dma/img-mdc-dma.c
  18 +++ b/drivers/dma/img-mdc-dma.c
  19 @@ -620,25 +620,33 @@ static enum dma_status mdc_tx_status(str
  20                         (MDC_CMDS_PROCESSED_CMDS_DONE_MASK + 1);
  21
  22                 /*
  23 -                * If the command loaded event hasn't been processed yet, then
  24 -                * the difference above includes an extra command.
  25 +                * If the first node has not yet been read from memory,
  26 +                * the residue register value is undefined
  27                  */
  28 -               if (!mdesc->cmd_loaded)
  29 -                       cmds--;
  30 -               else
  31 -                       cmds += mdesc->list_cmds_done;
  32 -
  33 -               bytes = mdesc->list_xfer_size;
  34 -               ldesc = mdesc->list;
  35 -               for (i = 0; i < cmds; i++) {
  36 -                       bytes -= ldesc->xfer_size + 1;
  37 -                       ldesc = ldesc->next_desc;
  38 -               }
  39 -               if (ldesc) {
  40 -                       if (residue != MDC_TRANSFER_SIZE_MASK)
  41 -                               bytes -= ldesc->xfer_size - residue;
  42 +               if (!mdesc->cmd_loaded && !cmds) {
  43 +                       bytes = mdesc->list_xfer_size;
  44 +               } else {
  45 +                       /*
  46 +                        * If the command loaded event hasn't been processed yet, then
  47 +                        * the difference above includes an extra command.
  48 +                        */
  49 +                       if (!mdesc->cmd_loaded)
  50 +                               cmds--;
  51                         else
  52 +                               cmds += mdesc->list_cmds_done;
  53 +
  54 +                       bytes = mdesc->list_xfer_size;
  55 +                       ldesc = mdesc->list;
  56 +                       for (i = 0; i < cmds; i++) {
  57                                 bytes -= ldesc->xfer_size + 1;
  58 +                               ldesc = ldesc->next_desc;
  59 +                       }
  60 +                       if (ldesc) {
  61 +                               if (residue != MDC_TRANSFER_SIZE_MASK)
  62 +                                       bytes -= ldesc->xfer_size - residue;
  63 +                               else
  64 +                                       bytes -= ldesc->xfer_size + 1;
  65 +                       }
  66                 }
  67         }
  68         spin_unlock_irqrestore(&mchan->vc.lock, flags);