drm: msm: Add ASoC generic hdmi audio codec support.

[karo-tx-linux.git] / drivers / dma / at_xdmac.c

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 370c661c7d7b25c237a3376dd18da79fbd44eadd..02f9aa4ebe05fef65fbdf5d5a55d1213b296541e 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) |\
@@ -1383,8 +1384,8 @@ 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;
 
@@ -1421,7 +1422,42 @@ 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
@@ -1434,7 +1470,7 @@ 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);
 
@@ -1688,6 +1724,7 @@ static int at_xdmac_device_terminate_all(struct dma_chan *chan)
        list_for_each_entry_safe(desc, _desc, &atchan->xfers_list, xfer_node)
                at_xdmac_remove_xfer(atchan, desc);
 
+       clear_bit(AT_XDMAC_CHAN_IS_PAUSED, &atchan->status);
        clear_bit(AT_XDMAC_CHAN_IS_CYCLIC, &atchan->status);
        spin_unlock_irqrestore(&atchan->lock, flags);
 
@@ -1820,6 +1857,8 @@ static int atmel_xdmac_resume(struct device *dev)
                atchan = to_at_xdmac_chan(chan);
                at_xdmac_chan_write(atchan, AT_XDMAC_CC, atchan->save_cc);
                if (at_xdmac_chan_is_cyclic(atchan)) {
+                       if (at_xdmac_chan_is_paused(atchan))
+                               at_xdmac_device_resume(chan);
                        at_xdmac_chan_write(atchan, AT_XDMAC_CNDA, atchan->save_cnda);
                        at_xdmac_chan_write(atchan, AT_XDMAC_CNDC, atchan->save_cndc);
                        at_xdmac_chan_write(atchan, AT_XDMAC_CIE, atchan->save_cim);