Re: [PATCH v2 3/4] media: aspeed: Correct values for detected timing

[Jammy Huang <jammy_huang@aspeedtech.com>]

Hi Hans,

Yes, this is a weird part of our hardware.
Because it uses the rising edge of the sync to start counting, an 
additional calculation
is needed to get the exact value of the timings.

This problem was found when I was debugging the timing detection 
unstable problem.

Reards,

Jammy

On 2022/1/20 下午 08:31, Hans Verkuil wrote:
> Hi Jammy,
>
> I just want to double check this: I assume you have tested this with the
> various polarity combinations?
>
> I ask because I've never seen this before in any other hardware. The
> sync and porch values reported by hardware are always independent from the
> polarity, so that's why I am surprised to see this.
>
> Same for the next patch (4/4).
>
> Regards,
>
> 	Hans
>
> On 12/22/21 09:21, Jammy Huang wrote:
>> Correct timing's fp/sync/bp value based on the information below.
>> It should be noticed that the calculation formula should be changed
>> per sync polarity.
>>
>> The sequence of signal: sync - backporch - video data - frontporch
>>
>> The following registers start counting from sync's rising edge:
>> 1. VR090: frame edge's left and right
>> 2. VR094: frame edge's top and bottom
>> 3. VR09C: counting from sync's rising edge to falling edge
>>
>> [Vertical timing]
>>              +--+     +-------------------+     +--+
>>              |  |     |    v i d e o      |     |  |
>>           +--+  +-----+                   +-----+  +---+
>>
>>         vsync+--+
>>     frame_top+--------+
>> frame_bottom+----------------------------+
>>
>>                    +-------------------+
>>                    |    v i d e o      |
>>        +--+  +-----+                   +-----+  +---+
>>           |  |                               |  |
>>           +--+                               +--+
>>         vsync+-------------------------------+
>>     frame_top+-----+
>> frame_bottom+-------------------------+
>>
>> [Horizontal timing]
>>              +--+     +-------------------+     +--+
>>              |  |     |    v i d e o      |     |  |
>>           +--+  +-----+                   +-----+  +---+
>>
>>         hsync+--+
>>    frame_left+--------+
>>   frame_right+----------------------------+
>>
>>                    +-------------------+
>>                    |    v i d e o      |
>>        +--+  +-----+                   +-----+  +---+
>>           |  |                               |  |
>>           +--+                               +--+
>>         hsync+-------------------------------+
>>    frame_left+-----+
>>   frame_right+-------------------------+
>>
>> Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
>> ---
>>   v2:
>>    - Code refined per Joel's suggestion
>>    - Update commit message to have name matching variable
>> ---
>>   drivers/media/platform/aspeed-video.c | 30 ++++++++++++++++++++-------
>>   1 file changed, 22 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/media/platform/aspeed-video.c b/drivers/media/platform/aspeed-video.c
>> index c241038ee27c..7c50567f5ab0 100644
>> --- a/drivers/media/platform/aspeed-video.c
>> +++ b/drivers/media/platform/aspeed-video.c
>> @@ -936,7 +936,7 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)
>>   	u32 src_lr_edge;
>>   	u32 src_tb_edge;
>>   	u32 sync;
>> -	u32 htotal;
>> +	u32 htotal, vtotal, vsync, hsync;
>>   	struct v4l2_bt_timings *det = &video->detected_timings;
>>   
>>   	det->width = MIN_WIDTH;
>> @@ -983,21 +983,35 @@ static void aspeed_video_get_resolution(struct aspeed_video *video)
>>   		mds = aspeed_video_read(video, VE_MODE_DETECT_STATUS);
>>   		sync = aspeed_video_read(video, VE_SYNC_STATUS);
>>   		htotal = aspeed_video_read(video, VE_H_TOTAL_PIXELS);
>> +		vtotal = FIELD_GET(VE_MODE_DETECT_V_LINES, mds);
>> +		vsync = FIELD_GET(VE_SYNC_STATUS_VSYNC, sync);
>> +		hsync = FIELD_GET(VE_SYNC_STATUS_HSYNC, sync);
>>   
>>   		video->frame_bottom = FIELD_GET(VE_SRC_TB_EDGE_DET_BOT, src_tb_edge);
>>   		video->frame_top = FIELD_GET(VE_SRC_TB_EDGE_DET_TOP, src_tb_edge);
>> -		det->vfrontporch = video->frame_top;
>> -		det->vbackporch = FIELD_GET(VE_MODE_DETECT_V_LINES, mds) -
>> -			video->frame_bottom;
>> -		det->vsync = FIELD_GET(VE_SYNC_STATUS_VSYNC, sync);
>> +		if (det->polarities & V4L2_DV_VSYNC_POS_POL) {
>> +			det->vbackporch = video->frame_top - vsync;
>> +			det->vfrontporch = vtotal - video->frame_bottom;
>> +			det->vsync = vsync;
>> +		} else {
>> +			det->vbackporch = video->frame_top;
>> +			det->vfrontporch = vsync - video->frame_bottom;
>> +			det->vsync = vtotal - vsync;
>> +		}
>>   		if (video->frame_top > video->frame_bottom)
>>   			continue;
>>   
>>   		video->frame_right = FIELD_GET(VE_SRC_LR_EDGE_DET_RT, src_lr_edge);
>>   		video->frame_left = FIELD_GET(VE_SRC_LR_EDGE_DET_LEFT, src_lr_edge);
>> -		det->hfrontporch = video->frame_left;
>> -		det->hbackporch = htotal - video->frame_right;
>> -		det->hsync = FIELD_GET(VE_SYNC_STATUS_HSYNC, sync);
>> +		if (det->polarities & V4L2_DV_HSYNC_POS_POL) {
>> +			det->hbackporch = video->frame_left - hsync;
>> +			det->hfrontporch = htotal - video->frame_right;
>> +			det->hsync = hsync;
>> +		} else {
>> +			det->hbackporch = video->frame_left;
>> +			det->hfrontporch = hsync - video->frame_right;
>> +			det->hsync = htotal - hsync;
>> +		}
>>   		if (video->frame_left > video->frame_right)
>>   			continue;
>>