releases/4.4.177/dmaengine-at_xdmac-fix-wrongfull-report-of-a-channel.patch

   1 From 6ee0b2d89a3e17e4f545ca6515f62b5f81870090 Mon Sep 17 00:00:00 2001
   2 From: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
   3 Date: Wed, 23 Jan 2019 16:33:47 +0000
   4 Subject: dmaengine: at_xdmac: Fix wrongfull report of a channel as in use
   5
   6 [ Upstream commit dc3f595b6617ebc0307e0ce151e8f2f2b2489b95 ]
   7
   8 atchan->status variable is used to store two different information:
   9  - pass channel interrupts status from interrupt handler to tasklet;
  10  - channel information like whether it is cyclic or paused;
  11
  12 This causes a bug when device_terminate_all() is called,
  13 (AT_XDMAC_CHAN_IS_CYCLIC cleared on atchan->status) and then a late End
  14 of Block interrupt arrives (AT_XDMAC_CIS_BIS), which sets bit 0 of
  15 atchan->status. Bit 0 is also used for AT_XDMAC_CHAN_IS_CYCLIC, so when
  16 a new descriptor for a cyclic transfer is created, the driver reports
  17 the channel as in use:
  18
  19 if (test_and_set_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status)) {
  20         dev_err(chan2dev(chan), "channel currently used\n");
  21         return NULL;
  22 }
  23
  24 This patch fixes the bug by adding a different struct member to keep
  25 the interrupts status separated from the channel status bits.
  26
  27 Fixes: e1f7c9eee707 ("dmaengine: at_xdmac: creation of the atmel eXtended DMA Controller driver")
  28 Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
  29 Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
  30 Signed-off-by: Vinod Koul <vkoul@kernel.org>
  31 Signed-off-by: Sasha Levin <sashal@kernel.org>
  32 ---
  33  drivers/dma/at_xdmac.c | 19 ++++++++++---------
  34  1 file changed, 10 insertions(+), 9 deletions(-)
  35
  36 diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
  37 index 82a7c89caae2..af24c5bf32d6 100644
  38 --- a/drivers/dma/at_xdmac.c
  39 +++ b/drivers/dma/at_xdmac.c
  40 @@ -203,6 +203,7 @@ struct at_xdmac_chan {
  41         u32                             save_cim;
  42         u32                             save_cnda;
  43         u32                             save_cndc;
  44 +       u32                             irq_status;
  45         unsigned long                   status;
  46         struct tasklet_struct           tasklet;
  47         struct dma_slave_config         sconfig;
  48 @@ -1582,8 +1583,8 @@ static void at_xdmac_tasklet(unsigned long data)
  49         struct at_xdmac_desc    *desc;
  50         u32                     error_mask;
  51
  52 -       dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08lx\n",
  53 -                __func__, atchan->status);
  54 +       dev_dbg(chan2dev(&atchan->chan), "%s: status=0x%08x\n",
  55 +               __func__, atchan->irq_status);
  56
  57         error_mask = AT_XDMAC_CIS_RBEIS
  58                      | AT_XDMAC_CIS_WBEIS
  59 @@ -1591,15 +1592,15 @@ static void at_xdmac_tasklet(unsigned long data)
  60
  61         if (at_xdmac_chan_is_cyclic(atchan)) {
  62                 at_xdmac_handle_cyclic(atchan);
  63 -       } else if ((atchan->status & AT_XDMAC_CIS_LIS)
  64 -                  || (atchan->status & error_mask)) {
  65 +       } else if ((atchan->irq_status & AT_XDMAC_CIS_LIS)
  66 +                  || (atchan->irq_status & error_mask)) {
  67                 struct dma_async_tx_descriptor  *txd;
  68
  69 -               if (atchan->status & AT_XDMAC_CIS_RBEIS)
  70 +               if (atchan->irq_status & AT_XDMAC_CIS_RBEIS)
  71                         dev_err(chan2dev(&atchan->chan), "read bus error!!!");
  72 -               if (atchan->status & AT_XDMAC_CIS_WBEIS)
  73 +               if (atchan->irq_status & AT_XDMAC_CIS_WBEIS)
  74                         dev_err(chan2dev(&atchan->chan), "write bus error!!!");
  75 -               if (atchan->status & AT_XDMAC_CIS_ROIS)
  76 +               if (atchan->irq_status & AT_XDMAC_CIS_ROIS)
  77                         dev_err(chan2dev(&atchan->chan), "request overflow error!!!");
  78
  79                 spin_lock_bh(&atchan->lock);
  80 @@ -1654,7 +1655,7 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
  81                         atchan = &atxdmac->chan[i];
  82                         chan_imr = at_xdmac_chan_read(atchan, AT_XDMAC_CIM);
  83                         chan_status = at_xdmac_chan_read(atchan, AT_XDMAC_CIS);
  84 -                       atchan->status = chan_status & chan_imr;
  85 +                       atchan->irq_status = chan_status & chan_imr;
  86                         dev_vdbg(atxdmac->dma.dev,
  87                                  "%s: chan%d: imr=0x%x, status=0x%x\n",
  88                                  __func__, i, chan_imr, chan_status);
  89 @@ -1668,7 +1669,7 @@ static irqreturn_t at_xdmac_interrupt(int irq, void *dev_id)
  90                                  at_xdmac_chan_read(atchan, AT_XDMAC_CDA),
  91                                  at_xdmac_chan_read(atchan, AT_XDMAC_CUBC));
  92
  93 -                       if (atchan->status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
  94 +                       if (atchan->irq_status & (AT_XDMAC_CIS_RBEIS | AT_XDMAC_CIS_WBEIS))
  95                                 at_xdmac_write(atxdmac, AT_XDMAC_GD, atchan->mask);
  96
  97                         tasklet_schedule(&atchan->tasklet);
  98 --
  99 2.19.1
 100