diff options
Diffstat (limited to 'drivers/gpu/host1x/cdma.c')
| -rw-r--r-- | drivers/gpu/host1x/cdma.c | 29 |
1 files changed, 25 insertions, 4 deletions
diff --git a/drivers/gpu/host1x/cdma.c b/drivers/gpu/host1x/cdma.c index 64099cc1964b..07df85b92ebf 100644 --- a/drivers/gpu/host1x/cdma.c +++ b/drivers/gpu/host1x/cdma.c @@ -41,7 +41,17 @@ * means that the push buffer is full, not empty. */ -#define HOST1X_PUSHBUFFER_SLOTS 512 +/* + * Typically the commands written into the push buffer are a pair of words. We + * use slots to represent each of these pairs and to simplify things. Note the + * strange number of slots allocated here. 512 slots will fit exactly within a + * single memory page. We also need one additional word at the end of the push + * buffer for the RESTART opcode that will instruct the CDMA to jump back to + * the beginning of the push buffer. With 512 slots, this means that we'll use + * 2 memory pages and waste 4092 bytes of the second page that will never be + * used. + */ +#define HOST1X_PUSHBUFFER_SLOTS 511 /* * Clean up push buffer resources @@ -143,7 +153,10 @@ static void host1x_pushbuffer_push(struct push_buffer *pb, u32 op1, u32 op2) WARN_ON(pb->pos == pb->fence); *(p++) = op1; *(p++) = op2; - pb->pos = (pb->pos + 8) & (pb->size - 1); + pb->pos += 8; + + if (pb->pos >= pb->size) + pb->pos -= pb->size; } /* @@ -153,7 +166,10 @@ static void host1x_pushbuffer_push(struct push_buffer *pb, u32 op1, u32 op2) static void host1x_pushbuffer_pop(struct push_buffer *pb, unsigned int slots) { /* Advance the next write position */ - pb->fence = (pb->fence + slots * 8) & (pb->size - 1); + pb->fence += slots * 8; + + if (pb->fence >= pb->size) + pb->fence -= pb->size; } /* @@ -161,7 +177,12 @@ static void host1x_pushbuffer_pop(struct push_buffer *pb, unsigned int slots) */ static u32 host1x_pushbuffer_space(struct push_buffer *pb) { - return ((pb->fence - pb->pos) & (pb->size - 1)) / 8; + unsigned int fence = pb->fence; + + if (pb->fence < pb->pos) + fence += pb->size; + + return (fence - pb->pos) / 8; } /* |