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What do I need to modify to add a custom resolution?
11-03-2019, 10:07 PM (Last edited: 11-03-2019, 10:11 PM by sun1987)
Post: #1
What do I need to modify to add a custom resolution?
The display is dell up3218k, the resolution is 7680*4320, using two dp lines, according to dell's documentation, because of the dp1.4 specification, 3218k can only be 8k, 48hz, 10bpc or 8k, 60hz, 8bpc.
I feel that two dp lines can support 8k, 60hz, 10bpc
2*DP1.4≈64.8G bps
8k 60hz 10bit=7680*4320*30*60/1024^3≈55.6G bps


Want to know, add 8k resolution, in addition to the resolution, Back porch, blankong, total and some other settings, do I need to modify?
Any help would be greatly appreciated

   
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11-03-2019, 10:58 PM
Post: #2
RE: What do I need to modify to add a custom resolution?
Well the first problem I see is CRU is not reading the extension blocks, which has the topology information needed to make the two streams work as one display. What video card do you have?

The second problem is since the monitor uses two streams, it should appear as two active displays in CRU, so each display would need to be 3840x4320 instead of 7680x4320, which the monitor already has defined in the extension blocks that you can't see, so there's no point in adding the same resolutions.

The third problem is your bandwidth calculations are wrong. Two DisplayPort 1.4 HBR3 streams gives 64.8 Gbps, but DisplayPort uses 8b/10b coding, so that gives a data rate of 51.84 Gbps. The data rate includes blanking, so you need to calculate with the totals, which in your screenshot is 8240x4410. Also, bits always use multiples of 1000, not 1024 like bytes.

8240 * 4410 * 60 Hz * 30-bit / 1000^3 = 65.40912 Gbps
8240 * 4410 * 60 Hz * 24-bit / 1000^3 = 52.327296 Gbps

You need to reduce the blanking just to get 24-bit to fit, so 30-bit has no chance.

The Dell UP3218K uses two streams at 4040x4368:

2 * 4040 * 4368 * 60 Hz * 24-bit / 1000^3 = 50.8225536 Gbps
2 * 4040 * 4368 * 48 Hz * 30-bit / 1000^3 = 50.8225536 Gbps

That barely fits within the data rate.
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11-04-2019, 05:31 AM
Post: #3
RE: What do I need to modify to add a custom resolution?
(11-03-2019 10:58 PM)ToastyX Wrote:  Well the first problem I see is CRU is not reading the extension blocks, which has the topology information needed to make the two streams work as one display. What video card do you have?

The second problem is since the monitor uses two streams, it should appear as two active displays in CRU, so each display would need to be 3840x4320 instead of 7680x4320, which the monitor already has defined in the extension blocks that you can't see, so there's no point in adding the same resolutions.

The third problem is your bandwidth calculations are wrong. Two DisplayPort 1.4 HBR3 streams gives 64.8 Gbps, but DisplayPort uses 8b/10b coding, so that gives a data rate of 51.84 Gbps. The data rate includes blanking, so you need to calculate with the totals, which in your screenshot is 8240x4410. Also, bits always use multiples of 1000, not 1024 like bytes.

8240 * 4410 * 60 Hz * 30-bit / 1000^3 = 65.40912 Gbps
8240 * 4410 * 60 Hz * 24-bit / 1000^3 = 52.327296 Gbps

You need to reduce the blanking just to get 24-bit to fit, so 30-bit has no chance.

The Dell UP3218K uses two streams at 4040x4368:

2 * 4040 * 4368 * 60 Hz * 24-bit / 1000^3 = 50.8225536 Gbps
2 * 4040 * 4368 * 48 Hz * 30-bit / 1000^3 = 50.8225536 Gbps

That barely fits within the data rate.

thank you for your reply。
The graphics card is radeon vii。

1,If I use ycbcr422,can I get 10bpc 72hz 8k?
2 * 4040 * 4368 * 72 Hz * 20-bit / 1000^3 = 50.8225536 Gbps

2,If so, how do I set the options?
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11-04-2019, 02:09 PM
Post: #4
RE: What do I need to modify to add a custom resolution?
(11-04-2019 05:31 AM)sun1987 Wrote:  1,If I use ycbcr422,can I get 10bpc 72hz 8k?
2 * 4040 * 4368 * 72 Hz * 20-bit / 1000^3 = 50.8225536 Gbps
In theory, yes, but that's assuming the monitor accepts higher refresh rates and doesn't skip frames, and you'd be losing color resolution. You would need to add 3840x4320 @ 72 Hz to each monitor with the totals set to 4040x4368.

Does Radeon Settings let you set YCbCr 4:2:2? You should be able to test 10 bpc with YCbCr 4:2:2 at 60 Hz without changing anything with CRU. If it won't let you do that, then CRU won't help.

Radeon VII should be able to read the extension blocks. Run this for me and post the log file:
.zip  amdtest.zip (Size: 455.21 KB / Downloads: 17)
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