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Date: Fri, 21 Jan 2022 08:28:41 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Jammy Huang <jammy_huang@...eedtech.com>, eajames@...ux.ibm.com,
mchehab@...nel.org, joel@....id.au, andrew@...id.au,
linux-media@...r.kernel.org, openbmc@...ts.ozlabs.org,
linux-arm-kernel@...ts.infradead.org,
linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] media: aspeed: Correct values for detected timing
Hi Jammy,
On 1/21/22 07:01, Jammy Huang wrote:
> 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.
OK, thank you for the confirmation.
I would like a v3 where basically the explanation you made in the cover letter
is copied to the code, probably as a comment block just before aspeed_video_get_resolution().
This is unusual enough that it should be documented well in the code.
Regards,
Hans
>
> 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@...eedtech.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;
>>>
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