Re: [PATCH v2 1/8] drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support

[Neil Armstrong]

Hi Rob,

On 14/03/2019 21:14, Rob Herring wrote:
> On Thu, Mar 14, 2019 at 3:07 PM Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote:
>>

[...]

> 
> Here's with edid-decode:
> 
> EDID version: 1.3
> Manufacturer: CYX Model 101 Serial Number 16843009
> Made in week 28 of 2018
> Digital display
> Maximum image size: 22 cm x 13 cm
> Gamma: 2.20
> DPMS levels: Off
> Undefined display color type
> Default (sRGB) color space is primary color space
> First detailed timing is preferred timing
> Display x,y Chromaticity:
>   Red:   0.6455, 0.3300
>   Green: 0.3095, 0.6171
>   Blue:  0.1523, 0.0732
>   White: 0.3134, 0.3291
> Established timings supported:
>   640x480@60Hz 4:3 HorFreq: 31469 Hz Clock: 25.175 MHz
>   800x600@60Hz 4:3 HorFreq: 37900 Hz Clock: 40.000 MHz
>   1024x768@60Hz 4:3 HorFreq: 48400 Hz Clock: 65.000 MHz
> Standard timings supported:
>   1920x1080@60Hz 16:9
>   1920x1080@60Hz 16:9
>   1920x1080@60Hz 16:9
>   1440x900@60Hz 16:10 HorFreq: 55500 Hz Clock: 88.750 MHz
>   1400x1050@60Hz 4:3 HorFreq: 64700 Hz Clock: 101.000 MHz
>   1280x1024@60Hz 5:4 HorFreq: 64000 Hz Clock: 108.000 MHz
>   1280x960@60Hz 4:3 HorFreq: 60000 Hz Clock: 108.000 MHz
>   1280x720@60Hz 16:9
> Detailed mode: Clock 267.810 MHz, 220 mm x 130 mm
>                2560 2608 2640 2720 hborder 0
>                1600 1603 1608 1641 vborder 0
>                +hsync +vsync
>                VertFreq: 59 Hz, HorFreq: 98459 Hz
> Monitor name: CYS-R101
> Serial number:
> Monitor ranges (bare limits): 48-75Hz V, 30-102kHz H, max dotclock 190MHz
> Has 1 extension blocks
> Checksum: 0x8b (valid)
> 
> CTA extension block
> Extension version: 3
> 58 bytes of CTA data
>   Video data block
>     VIC  16 1920x1080@60Hz 16:9  HorFreq: 67500 Hz Clock: 148.500 MHz
>     VIC   5 1920x1080i@60Hz 16:9  HorFreq: 33750 Hz Clock: 74.250 MHz
>     VIC   4 1280x720@60Hz 16:9  HorFreq: 45000 Hz Clock: 74.250 MHz
>     VIC  31 1920x1080@50Hz 16:9  HorFreq: 56250 Hz Clock: 148.500 MHz
>   Audio data block
>     Linear PCM, max channels 2
>       Supported sample rates (kHz): 48 44.1 32
>       Supported sample sizes (bits): 24 20 16
>   Speaker allocation data block
>     Speaker map:
>       FL/FR - Front Left/Right
>   Vendor-specific data block, OUI 000c03 (HDMI)
>     Source physical address 1.0.0.0
>     DC_36bit
>     DC_30bit
>     DC_Y444
>     Maximum TMDS clock: 340MHz
>   Vendor-specific data block, OUI c45dd8 (HDMI Forum)
>     Version: 1
>     Maximum TMDS Character Rate: 340MHz
>     SCDC Present
>     Supports 10-bits/component Deep Color 4:2:0 Pixel Encoding
>   Vendor-specific data block, OUI 00001a
>   Extended tag: YCbCr 4:2:0 capability map data block
>     VSD Index 17
>     VSD Index 18
>   Extended tag: Colorimetry data block
>     BT2020YCC
>     BT2020RGB
>   Extended tag: Video capability data block
>     YCbCr quantization: Selectable (via AVI YQ) (1)
>     RGB quantization: Selectable (via AVI Q) (1)
>     PT scan behaviour: Support both over- and underscan (3)
>     IT scan behaviour: Support both over- and underscan (3)
>     CE scan behaviour: Support both over- and underscan (3)
>   Extended tag: HDR static metadata data block
>     Electro optical transfer functions:
>       Traditional gamma - SDR luminance range
>       SMPTE ST2084
>     Supported static metadata descriptors:
>       Static metadata type 1
>     Desired content max luminance: 89 (343.724 cd/m^2)
>     Desired content max frame-average luminance: 89 (343.724 cd/m^2)
>     Desired content min luminance: 73 (0.282 cd/m^2)
> Underscans PC formats by default
> Basic audio support
> Supports YCbCr 4:4:4
> Supports YCbCr 4:2:2
> 1 native detailed modes
> Detailed mode: Clock 54.000 MHz, 220 mm x 130 mm
>                2560 2608 2640 2720 hborder 0
>                1440 1443 1448 1481 vborder 0
>                +hsync +vsync side by side interleaved
>                VertFreq: 13 Hz, HorFreq: 19852 Hz
> Checksum: 0x3c (valid)
> 


Thanks for the parsed edid.

I think we have multiple issues :
- This EDID is severely broken, SCDC support doesn't make sense because
"Maximum TMDS Character Rate: 340MHz" and "Supports scrambling for <= 340 Mcsc" is not present
Same for 4:2:0, the IDs in the "YCbCr 4:2:0 capability map data block" refers
to invalid modes 17 & 18 in a mode table containing only 4 entries.
- DW-HDMI should not care if SCDC is present, Max TMDS <= 340MHz and low_rates is not present
- In any case, the SoC should not freeze in this situation, so either the
HDMI_FC_SCRAMBLER_CTRL or HDMI_MC_SWRSTZ writes makes the SoC freeze or
the drm_scdc_set_scrambling() containing i2c write fails, anyway this is
the root issue.

This will need 3 steps :
- an entry in the EDID quirk table to disable SCDC and 420 for this monitor
- a fix in dw-hdmi to ignore this SCDC setup
- an investigation to find why and where the SoC did freeze

Rob, could you give the Commercial name of the display for the EDID quirk table ?

Thanks,

Neil