Hi Krzysztof,
On 05/24/2018 08:56 AM, Krzysztof Hałasa wrote:
Hi,
I've experimented with the ADV7180 a bit and this is what I found.
First, I'm using (with a NTSC camera but I guess PAL won't be much
different):
media-ctl -V '"adv7180 2-0020":0[fmt:UYVY2X8 720x480 field:interlaced]'
media-ctl -V '"ipu2_csi1_mux":1[fmt:UYVY2X8 720x480 field:interlaced]'
media-ctl -V '"ipu2_csi1_mux":2[fmt:UYVY2X8 720x480 field:interlaced]'
media-ctl -V '"ipu2_csi1":0[fmt:UYVY2X8 720x480 field:interlaced]'
media-ctl -V '"ipu2_csi1":2[fmt:UYVY2X8 720x480 field:interlaced]'
IOW I set all of the parts to interlaced mode. If i set the last element
to "none", the CSI is not set for interlaced input, and nothing works at
the low level.
This is what I don't understand. By setting pad ipu2_csi1:2 to
"none", the if statement below should be true (sink pad field
is "interlaced" and the capture field is propagated from ipu2_csi1:2
field so it is "none", thus ipu_cpmem_interlaced_scan() will be called.
And yes you are correct, ipu_cpmem_interlaced_scan() must be
called to enable IDMAC interweave, which is what you want.
This requires a quick temporary hack:
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -474,8 +474,8 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
ipu_smfc_set_burstsize(priv->smfc, burst_size);
- if (image.pix.field == V4L2_FIELD_NONE &&
- V4L2_FIELD_HAS_BOTH(infmt->field))
+ if (1 || (image.pix.field == V4L2_FIELD_NONE &&
+ V4L2_FIELD_HAS_BOTH(infmt->field)))
ipu_cpmem_interlaced_scan(priv->idmac_ch,
image.pix.bytesperline);
I.e., I need to set CPMEM to interlaced mode when I operate CSI in
interlaced mode. The original code is a bit unclear to me in fact.
No the code above is not unclear at all. The if statement is saying
that if the user wants progressive output (V4L2_FIELD_NONE), and
the input contains fields, then turn on interweave in the IDMAC
channel.
This might be a good time to bring up the fact that the ADV7180 driver
is wrong
to set output to "interlaced". The ADV7180 does not transmit top lines
interlaced
with bottom lines. It transmits all top lines followed by all bottom
lines (or
vice-versa), i.e. it should be either V4L2_FIELD_SEQ_TB or
V4L2_FIELD_SEQ_BT.
It can also be set to V4L2_FIELD_ALTERNATE, and then it is left up to
downstream
elements to determine field order (TB or BT).
I've previously sent a patch to fix this at
https://patchwork.linuxtv.org/patch/36193/
but it got lost. Niklas has said he will pick this up again.
The following is required as well. Now the question is why we can't skip
writing those odd UV rows. Anyway, with these 2 changes, I get a stable
NTSC (and probably PAL) interlaced video stream.
The manual says: Reduce Double Read or Writes (RDRW):
This bit is relevant for YUV4:2:0 formats. For write channels:
U and V components are not written to odd rows.
How could it be so? With YUV420, are they normally written?
Well, given that this bit exists, and assuming I understand it correctly
(1),
I guess the U and V components for odd rows normally are placed on the
AXI bus. Which is a total waste of bus bandwidth because in 4:2:0,
the U and V components are the same for odd and even rows.
In other words for writing 4:2:0 to memory, this bit should _always_ be set.
(1) OTOH I don't really understand what this bit is trying to say.
Whether this bit is set or not, the data in memory is correct
for planar 4:2:0: y plane buffer followed by U plane of 1/4 size
(decimated by 2 in width and height), followed by Y plane of 1/4
size.
So I assume it is saying that the IPU normally places U/V components
on the AXI bus for odd rows, that are identical to the even row values.
IOW somehow those identical odd rows are dropped before writing to
the U/V planes in memory.
Philipp please chime in if you have something to add here.
Steve
OTOH it seems that not only UV is broken with this bit set.
Y is broken as well.
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -413,14 +413,12 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
passthrough_bits = 16;
break;
case V4L2_PIX_FMT_YUV420:
case V4L2_PIX_FMT_NV12:
burst_size = (image.pix.width & 0x3f) ?
((image.pix.width & 0x1f) ?
((image.pix.width & 0xf) ? 8 : 16) : 32) : 64;
passthrough = is_parallel_16bit_bus(&priv->upstream_ep);
passthrough_bits = 16;
- /* Skip writing U and V components to odd rows */
- ipu_cpmem_skip_odd_chroma_rows(priv->idmac_ch);
break;
case V4L2_PIX_FMT_YUYV:
case V4L2_PIX_FMT_UYVY:
