V4L/DVB: ivtv: Fix ivtv_api_get_data() to avoid unneeded IO during IRQ handling

ivtv_api_get_data() was performing more PCI MMIO than needed, resulting
often in it accounting for more than half the total time spent in
ivtv_irq_handler().  Now it only reads at most 7 of the 16 mailbox data words
over the PCI bus, and in some instances only 2 or 3 data words as needed.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/media/video/ivtv/ivtv-irq.c b/drivers/media/video/ivtv/ivtv-irq.c
index ee0cdded69f7..12d36ca91d53 100644
--- a/drivers/media/video/ivtv/ivtv-irq.c
+++ b/drivers/media/video/ivtv/ivtv-irq.c
@@ -562,7 +562,7 @@ static void ivtv_irq_enc_dma_complete(struct ivtv *itv)
         u32 data[CX2341X_MBOX_MAX_DATA];
         struct ivtv_stream *s;
 
-        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA_END, data);
+        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA_END, 2, data);
         IVTV_DEBUG_HI_IRQ("ENC DMA COMPLETE %x %d (%d)\n", data[0], data[1], itv->cur_dma_stream);
 
         del_timer(&itv->dma_timer);
@@ -638,7 +638,7 @@ static void ivtv_irq_dma_err(struct ivtv *itv)
         u32 data[CX2341X_MBOX_MAX_DATA];
 
         del_timer(&itv->dma_timer);
-        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA_END, data);
+        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA_END, 2, data);
         IVTV_DEBUG_WARN("DMA ERROR %08x %08x %08x %d\n", data[0], data[1],
                                 read_reg(IVTV_REG_DMASTATUS), itv->cur_dma_stream);
         write_reg(read_reg(IVTV_REG_DMASTATUS) & 3, IVTV_REG_DMASTATUS);
@@ -669,7 +669,7 @@ static void ivtv_irq_enc_start_cap(struct ivtv *itv)
         struct ivtv_stream *s;
 
         /* Get DMA destination and size arguments from card */
-        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA, data);
+        ivtv_api_get_data(&itv->enc_mbox, IVTV_MBOX_DMA, 7, data);
         IVTV_DEBUG_HI_IRQ("ENC START CAP %d: %08x %08x\n", data[0], data[1], data[2]);
 
         if (data[0] > 2 || data[1] == 0 || data[2] == 0) {
@@ -713,9 +713,9 @@ static void ivtv_irq_dec_data_req(struct ivtv *itv)
         struct ivtv_stream *s;
 
         /* YUV or MPG */
-        ivtv_api_get_data(&itv->dec_mbox, IVTV_MBOX_DMA, data);
 
         if (test_bit(IVTV_F_I_DEC_YUV, &itv->i_flags)) {
+                ivtv_api_get_data(&itv->dec_mbox, IVTV_MBOX_DMA, 2, data);
                 itv->dma_data_req_size =
                                  1080 * ((itv->yuv_info.v4l2_src_h + 31) & ~31);
                 itv->dma_data_req_offset = data[1];
@@ -724,6 +724,7 @@ static void ivtv_irq_dec_data_req(struct ivtv *itv)
                 s = &itv->streams[IVTV_DEC_STREAM_TYPE_YUV];
         }
         else {
+                ivtv_api_get_data(&itv->dec_mbox, IVTV_MBOX_DMA, 3, data);
                 itv->dma_data_req_size = min_t(u32, data[2], 0x10000);
                 itv->dma_data_req_offset = data[1];
                 s = &itv->streams[IVTV_DEC_STREAM_TYPE_MPG];