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- Fix busdma sync: dcache invalidation operates on cache line aligned

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addresses and could modify areas of memory that share the same cache
  line at the beginning and at the ending of the buffer. In order to
  prevent a data loss we save these chunks in temporary buffer before
  invalidation and restore them afer it.

Idea suggested by: cognet
This commit is contained in:
Oleksandr Tymoshenko 2009-10-28 03:34:05 +00:00
parent 0ffd7b6759
commit 1453f4e112
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/projects/mips/; revision=198534
1 changed files with 47 additions and 4 deletions
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51
sys/mips/mips/busdma_machdep.c
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@ -1029,10 +1029,43 @@ _bus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
static void
bus_dmamap_sync_buf(void *buf, int len, bus_dmasync_op_t op)
{
char tmp_cl[mips_pdcache_linesize], tmp_clend[mips_pdcache_linesize];
vm_offset_t buf_cl, buf_clend;
vm_size_t size_cl, size_clend;
int cache_linesize_mask = mips_pdcache_linesize - 1;
/*
* dcache invalidation operates on cache line aligned addresses
* and could modify areas of memory that share the same cache line
* at the beginning and the ending of the buffer. In order to
* prevent a data loss we save these chunks in temporary buffer
* before invalidation and restore them afer it
*/
buf_cl = (vm_offset_t)buf & ~cache_linesize_mask;
size_cl = (vm_offset_t)buf & cache_linesize_mask;
buf_clend = (vm_offset_t)buf + len;
size_clend = (mips_pdcache_linesize -
(buf_clend & cache_linesize_mask)) & cache_linesize_mask;
switch (op) {
case BUS_DMASYNC_POSTREAD | BUS_DMASYNC_POSTWRITE:
case BUS_DMASYNC_POSTREAD:
/*
* Save buffers that might be modified by invalidation
*/
if (size_cl)
memcpy (tmp_cl, (void*)buf_cl, size_cl);
if (size_clend)
memcpy (tmp_clend, (void*)buf_clend, size_clend);
mips_dcache_inv_range((vm_offset_t)buf, len);
/*
* Restore them
*/
if (size_cl)
memcpy ((void*)buf_cl, tmp_cl, size_cl);
if (size_clend)
memcpy ((void*)buf_clend, tmp_clend, size_clend);
break;
case BUS_DMASYNC_PREREAD|BUS_DMASYNC_PREWRITE:
@ -1040,11 +1073,21 @@ bus_dmamap_sync_buf(void *buf, int len, bus_dmasync_op_t op)
break;
case BUS_DMASYNC_PREREAD:
#if 0
mips_dcache_wbinv_range((vm_offset_t)buf, len);
#else
/*
* Save buffers that might be modified by invalidation
*/
if (size_cl)
memcpy (tmp_cl, (void *)buf_cl, size_cl);
if (size_clend)
memcpy (tmp_clend, (void *)buf_clend, size_clend);
mips_dcache_inv_range((vm_offset_t)buf, len);
#endif
/*
* Restore them
*/
if (size_cl)
memcpy ((void *)buf_cl, tmp_cl, size_cl);
if (size_clend)
memcpy ((void *)buf_clend, tmp_clend, size_clend);
break;
case BUS_DMASYNC_PREWRITE: