Merge tag 'dmaengine-fix-4.5' of git://git.infradead.org/users/vkoul/slave-dma

Pull dmaengine fixes from Vinod Koul:
 "Two fixes showed up in last few days, and they should be included in
  4.5.  Summary:

  Two more late fixes to drivers, nothing major here:

   - A memory leak fix in fsdma unmap the dma descriptors on freeup

   - A fix in xdmac driver for residue calculation of dma descriptor"

* tag 'dmaengine-fix-4.5' of git://git.infradead.org/users/vkoul/slave-dma:
  dmaengine: at_xdmac: fix residue computation
  dmaengine: fsldma: fix memory leak

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 64f5d1bdbb48defdddc4c7ed7ee0c5b988b92e1b..8e304b1befc56385b8fc34d7697a529289d8ae3b 100644 (file)
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -176,6 +176,7 @@
 #define AT_XDMAC_MAX_CHAN      0x20
 #define AT_XDMAC_MAX_CSIZE     16      /* 16 data */
 #define AT_XDMAC_MAX_DWIDTH    8       /* 64 bits */
+#define AT_XDMAC_RESIDUE_MAX_RETRIES   5
 
 #define AT_XDMAC_DMA_BUSWIDTHS\
        (BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED) |\
@@ -1395,8 +1396,8 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
        struct at_xdmac_desc    *desc, *_desc;
        struct list_head        *descs_list;
        enum dma_status         ret;
-       int                     residue;
-       u32                     cur_nda, mask, value;
+       int                     residue, retry;
+       u32                     cur_nda, check_nda, cur_ubc, mask, value;
        u8                      dwidth = 0;
        unsigned long           flags;
 
@@ -1433,7 +1434,42 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                        cpu_relax();
        }
 
+       /*
+        * When processing the residue, we need to read two registers but we
+        * can't do it in an atomic way. AT_XDMAC_CNDA is used to find where
+        * we stand in the descriptor list and AT_XDMAC_CUBC is used
+        * to know how many data are remaining for the current descriptor.
+        * Since the dma channel is not paused to not loose data, between the
+        * AT_XDMAC_CNDA and AT_XDMAC_CUBC read, we may have change of
+        * descriptor.
+        * For that reason, after reading AT_XDMAC_CUBC, we check if we are
+        * still using the same descriptor by reading a second time
+        * AT_XDMAC_CNDA. If AT_XDMAC_CNDA has changed, it means we have to
+        * read again AT_XDMAC_CUBC.
+        * Memory barriers are used to ensure the read order of the registers.
+        * A max number of retries is set because unlikely it can never ends if
+        * we are transferring a lot of data with small buffers.
+        */
        cur_nda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA) & 0xfffffffc;
+       rmb();
+       cur_ubc = at_xdmac_chan_read(atchan, AT_XDMAC_CUBC);
+       for (retry = 0; retry < AT_XDMAC_RESIDUE_MAX_RETRIES; retry++) {
+               rmb();
+               check_nda = at_xdmac_chan_read(atchan, AT_XDMAC_CNDA) & 0xfffffffc;
+
+               if (likely(cur_nda == check_nda))
+                       break;
+
+               cur_nda = check_nda;
+               rmb();
+               cur_ubc = at_xdmac_chan_read(atchan, AT_XDMAC_CUBC);
+       }
+
+       if (unlikely(retry >= AT_XDMAC_RESIDUE_MAX_RETRIES)) {
+               ret = DMA_ERROR;
+               goto spin_unlock;
+       }
+
        /*
         * Remove size of all microblocks already transferred and the current
         * one. Then add the remaining size to transfer of the current
@@ -1446,7 +1482,7 @@ at_xdmac_tx_status(struct dma_chan *chan, dma_cookie_t cookie,
                if ((desc->lld.mbr_nda & 0xfffffffc) == cur_nda)
                        break;
        }
-       residue += at_xdmac_chan_read(atchan, AT_XDMAC_CUBC) << dwidth;
+       residue += cur_ubc << dwidth;
 
        dma_set_residue(txstate, residue);
 

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index 2209f75fdf05bf29114f0fb3ffedff89f55b43f3..aac85c30c2cf6fc64669841c5b6abb5317df1b94 100644 (file)
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -522,6 +522,8 @@ static dma_cookie_t fsldma_run_tx_complete_actions(struct fsldma_chan *chan,
                        chan_dbg(chan, "LD %p callback\n", desc);
                        txd->callback(txd->callback_param);
                }
+
+               dma_descriptor_unmap(txd);
        }
 
        /* Run any dependencies */