SYNA DRM / KMS Driver User Guide
Introduction
Overview
The scope of the document is to provide detailed steps to configure and unit test drm/kms driver for SL16xx display interfaces.
This document emphasizes on MIPI-DSI related configuration like timing, initialization command, etc.
Acronyms
MIPI - Mobile Industry Processor Interface
LCD – Liquid Crystal Display
TFT – Thin Film Transistor
DRM – Direct Rendering Manager
KMS – Kernel Mode Setting
Astra Machina Display Capabilities
syna drm/kms driver is supported for the SL16xx Astra Machina platforms.
Display capability of the supported SoC’s.
SL1640: Supports Single Display (Either HDMI or MIPI-DSI)
SL1680: Supports Dual Display (HDMI and MIPI-DSI)
SL1620: Supports Dual Display (TFT and MIPI-DSI)
SYNA DRM/KMS Configuration
Device driver configurations are handled through the defconfig and dts files.
Configuration based on defconfig
Following device driver configuration available in defconfig:
DRM/KMS driver
Backlight
defconfig for each platform is given below:
SL1620: myna2_defconfig
SL1640: platypus_defconfig
SL1680: dolphin_defconfig
Configuration based on dts
Following device configuration are handled through dts files:
Generic Display configuration
MIPI-DSI Panel configuration
LCDC panel configuration
HDMI TX configuration
dts files of each platform given below:
SL1620: myna2-rdk.dts
SL1640: platypus-rdk.dts
SL1680: dolphin-rdk.dts
dts configuration template for SL16XX given below:
dts for SL1640 and SL1680
&drm {
Generic Display configuration
MIPI-DSI Panel configuration
HDMI TX configuration
}
dts for SL1620
&drm {
MIPI-DSI Panel configuration
LCDC panel specific configuration
}
Generic Display Configuration
For SL1640 or SL1680, the default display type on bootup need be specified.
Below are the parameters which need be configured for the display.
disp-mode: Specifies the display mode. Whether it is single display/ dual display.
disp1-res-id: Resolution Id corresponding to a timing information.
More information on the timing and resolution id are available in below file.
<linux>/drivers/soc/berlin/modules/avio/vpp/ca/include/vpp_defines.h
disp1-type: Type of the Display1 whether it is HDMI or MIPI-DSI.
disp2-res-id: Resolution Id corresponding to the timing information. In case of dual Display, display2 must be MIPI-DSI and resolution id is fixed to 102.
disp2-type: Type of the Display2.
SL1640/SL1680 Single Display configuration
Default configuration for SL1640 and SL1680 given as below.
SL1640 - Single Display mode – HDMI only.
SL1680 - Dual Display mode – HDMI + MIPI-DSI
Display mode can be changed in dts. Single Display mode is applicable for both SL1640 and SL1680.
Below is an example for Single display mode.
Single Display: HDMI Display Mode
&drm {
disp-mode = <0>;
disp1-res-id = <24>;
disp1-type = <0>;
};
Single Display mode: MIPI-DSI Display Mode
&drm {
disp-mode = <1>;
disp1-res-id = <102>;
disp1-type = <3>;
};
SL1680 Dual Display configuration
Dual Display Mode (HDMI as primary + DSI as secondary)
&drm {
disp-mode = <2>;
disp1-res-id = <24>;
disp1-type = <0>;
disp2-res-id = <102>;
disp2-type = <3>;
};
Note:
For MIPI-DSI Display: RESID is fixed to 102 where it takes the custom timing provided in the dts.
For HDMI display ID, depending on the capability of the SINK at bootup only 4K or 1080P are supported at present.
SL1620 Display configuration
Default display configuration for SL1620 is Dual – TFT + MIPI-DSI.
lcdc_panel node and dsi_panel nodes in dts decide the number of displays. Display configuration will be carried on based on the parameters in section 4.5 and section 4.3 respectively.
HDMI configuration
HDMI configuration options in dts are as below:
hdtx-core-config: used to configure HDMI output, it includes bitfields to control below options.
Default options: hdtx-core-config = /bits/ 8 <1 0 1>
HPD handling: to enable/disable handling of sink hotplug. If HPD handling is disabled, output format will be configured on bootup depending on sink capability and retained till next reboot.
HDCP control: to enable/disabled HDCP. Currently not handled.
FixedModeset: to let SYNA DRM/KMS driver handle the mode setting internally without exposing user interface. If set, it will configure output format without requiring the userspace application to configure output format, any attempt to override the configured format will be ignored.
hdtx-supported-formats: used to list the formats exposed to user via kms mode query.
Default selection: hdtx-supported-formats = /bits/ 8 <12 9 10 13 22 21 19 26 25 24 61 62 64>.
Refer below file for resolution indices in <linux>/drivers/soc/berlin/modules/avio/vpp/ca/include/vpp_defines.h
If needed, this can be overridden using parameter “hdmi_preferred_mode “, by adding/modifying the same in /etc/modprobe.d/syna_drm.conf.
Example: To override preferred modes as 1080p: hdmi_preferred_mode=1920x1080
Below is out of box default configuration,
syna drm/kms driver will internally configure HDMI output format.
On connecting 4K supported sink, 4K30 RGB 8bit format will be selected.
On 1080p TV, output will be configured as 1080p60 RGB 8bit.
Preferred mode of EDID is override to 1080p.
MIPI-DSI Display Configuration
MIPI-DSI panel configuration parameters
Lanes - Number of Data lanes
Data_Lane_Polarity - Polarity of the Data Lane
Clk_Lane_Polarity - Polarity of the clock lane
virtual_chan - virtual channel number
Vid_mode - Video mode. Supported video mode are:
0 - non-burst mode + sync pulse
1 - non-burst mode + sync event
2 - Burst mode
non-Continuous_clk - 0 for continuous and 1 for non-continuous clock configuration
Byte_clk - Byte clock rate. Calculated as Total Bandwidth / (Lanes * 8)
Recv_ack - Receive acknowledgement.
Color_format - Color coding output format
RGB888 - 5
Loosely_18 - Loosely 18 packed
Data_Polarity – Data enable signal. Assertion indicates valid pixel. 0 – Positive & 1 - negative
H_polarity - Horizontal polarity active low/High
V_Polarity - Vertical polarity
Eotp_rx - EOTP Reception support enable/disable.
Eotp_tx - EOTP Transmission enable/disable.
HTOTAL – Total number of pixels in a line.
Chunks - Number of Chunks in case of multiple chunk transmission otherwise ‘1’ for single.
Null_Pkt - Size of the null packet.
dpi_lp_cmd - Enable DPI low power command.
ACTIVE_WIDTH - Active width of the Panel
ACTIVE_HEIGHT - Active height of the panel
HFP - Horizontal Front porch
HSYNCWIDTH - Horizontal sync width
HBP - Horizontal Back porch
VFP - vertical Front porch
VSYNCWIDTH - Vertical sync width
VBP - Vertical Back porch
TYPE - ‘0’ for SD, ‘1’ for Full HD ‘2’ for UHD
SCAN - ‘1’ for Progressive, ‘0’ for Interlaced
FRAME_RATE - Frame rate, ENUMs mentioned as below.
FRAME_RATE_23P98 = 0
FRAME_RATE_24 = 1
FRAME_RATE_25 = 2
FRAME_RATE_29P97 = 3
FRAME_RATE_30 = 4
FRAME_RATE_47P96 = 5
FRAME_RATE_48 = 6
FRAME_RATE_50 = 7
FRAME_RATE_59P94 = 8
FRAME_RATE_60 = 9
FRAME_RATE_100 = 10
FRAME_RATE_119P88 = 11
FRAME_RATE_120 = 12
FRAME_RATE_89P91 = 13
FRAME_RATE_90 = 14
FLAG_3D – Disabled always.
PIXEL_CLOCK - Pixel clock frequency for Secondary display in KHz. Make it same as FREQ.
COMMAND = Command for initialization in Hex
Format - <CMD> <Payloadlength-n> <BYTE1> <…> <BYTEn>
Long write Ex: 39 04 FF 98 81 03
CMD => 0x39
Length => 0x04
PayLoad => FF 98 81 03
Delay in microseconds Command format: 0xFF <4BYTE delay>
Delay for 100ms (100000us => 0x000186A0)
FF A0 86 01 00
Display Timing Parameters
These parameters are mandatory for SL1640/SL1680 and optional for SL1620.
VB_MIN - Minimum vertical blanking for the Display TG
HB_MIN - Minimum Horizontal blanking for the Display TG
V_OFF - Vertical offset for the Display TG.
H_OFF - Horizontal offset for the Display TG.
HB_VOP_OFF - Horizontal VOP offset for the Display TG.
VB_VOP_OFF - Vertical VOP offset for the Display TG
HB_BE - Horizontal Blanking Back Edge for the Display TG.
VB_BE - Vertical Blanking Back Edge for the Display TG.
HB_FP - Horizontal Blanking Front porch for the Display TG.
VB_FP - Vertical Blanking Front porch for the Display TG.
Reference entry for the MIPI DSI panel
Below is default entry for the MIPI-DSI in dts.
This serves as a reference for a panel with resolution 800x1280 and HTotal = 952, VTOTAL = 1312.
Refer the parameters above for further information on the panel.
&drm {
…
dsi_panel {
status= “okay”;
/* Reset PIN configuration for the MIPI-DSI if available in the platform */
mipirst-gpio = <&expander0 7 GPIO_ACTIVE_LOW>;
NO_OF_RESID = <1>;
DSI_RES = <102>;
ACTIVE_WIDTH = <800>;
HFP = <60>;
HSYNCWIDTH = <32>;
HBP = <60>;
ACTIVE_HEIGHT = <1280>;
VFP = <16>;
VSYNCWIDTH = <2>;
VBP = <14>;
TYPE = <1>;
SCAN = <0>;
FRAME_RATE = <9>;
FLAG_3D = <0>;
FREQ = <75000>;
PTS_PER_4 = <6000>;
bits_per_pixel = <24>;
busformat = <0>;
HTOTAL = <952>;
Lanes = /bits/ 8 <4>;
Vid_mode = /bits/ 8 <2>;
virtual_chan = /bits/ 8 <0>;
Clk_Lane_Polarity = /bits/ 8 <0>;
Data_Lane_Polarity = /bits/ 8 <0>;
Recv_ack = /bits/ 8 <0>;
Loosely_18 = /bits/ 8 <0>;
H_polarity = /bits/ 8 <1>;
V_Polarity = /bits/ 8 <1>;
Data_Polarity = /bits/ 8 <1>;
Eotp_tx = /bits/ 8 <1>;
Eotp_rx = /bits/ 8 <0>;
non-Continuous_clk = /bits/ 8 <1>;
dpi_lp_cmd = /bits/ 8 <1>;
Color_coding = /bits/ 8 <5>;
Chunks = <0>;
Null_Pkt = <0>;
Byte_clk = <56250>;
VB_MIN = /bits/ 8 <6>;
HB_MIN = /bits/ 8 <30>;
V_OFF = /bits/ 8 <6>;
H_OFF = /bits/ 8 <20>;
HB_VOP_OFF = /bits/ 8 <8>;
VB_VOP_OFF = /bits/ 8 <3>;
HB_BE = /bits/ 8 <7>;
VB_BE = /bits/ 8 <2>;
VB_FP = /bits/ 8 <2>;
HB_FP = /bits/ 8 <10>;
PIXEL_CLOCK = <75000>;
command = /bits/ 8 <0x39 0x04 0xFF 0x98 0x81 0x03
0x15 0x02 0x01 0x00
…..
…..
0xFF 0xC0 0xD4 0x01 0x00
0x05 0x01 0x29
0xFF 0x10 0x27 0x00 0x00>;
};
};
TFT Display configuration
TBA
Panel Backlight Configuration
Panel Backlight enable using Linux defconfig and dts.
1. External backlight driver-based Panel (Example: TI LP855x part of Panel DC)
Enable backlight driver in Linux kernel defconfig.
-CONFIG_BACKLIGHT_CLASS_DEVICE=m
+CONFIG_BACKLIGHT_CLASS_DEVICE=y
-# CONFIG_BACKLIGHT_LP855X is not set
+CONFIG_BACKLIGHT_LP855X=y
Create the entry in dts file for backlight driver.
backlight@2c {
compatible = “ti, lp8556”;
reg = <0x2c>;
bl-name = “lcd-bl”;
dev-ctrl = /bits/ 8 <0x05>;
init-brt = /bits/ 8 <0xFF>;
pwm-period = /bits/ 8 <0x00>;
/* CFG2 */
rom_A2h {
rom-addr = /bits/ 8 <0xA2>;
rom-val = /bits/ 8 <0x28>;
};
Panel using SL16xx SOC PWM to control the backlight.
Kernel dts:
Configure the pinmux to support the PWM Backlight configuration in the dts file. Below are the details for sample panel and SL1680 platform.
panel0-backlight {
compatible = “pwm-backlight”;
pwms = <&***pwm0* 1 1000000 0>;
brightness-levels = <0 4 8 16 32 64 128 255>;
default-brightness-level = <6>;
enable-gpio = <&expander0 4 GPIO_ACTIVE_HIGH>;
};
pwm1_pmux: pwm1-pmux {
groups = “SPI1_SS1n”;
function = “pwm”;
}
&pwm0 {
pinctrl-names = “default”;
pinctrl-0 = <&pwm1_pmux>;
status = “okay”;
};
SYNA DRM/KMS driver testing
Upon SL1XXX platform boot-up, display comes up with Weston desktop by default.
To execute sample test application such as modetest, disable Weston using below command.
systemctl stop Weston
modetest is a tool provided by libdrm library and is available as part of the SDK release/image (/usr/local/bin/modetest)
Following are some of the tasks performed with modetest
List all display capabilities: CRTCs, encoders & connectors (DP, HDMI, DSI …), planes, modes…
Perform basic tests: display a test pattern, display 2 layers, perform a vsync test.
Specify the video mode: resolution and refreshrate.
Below is the syntax.
modetest -M synaptics -s <connector_id> [, <connector_id>][@<crtc_id>]:[#<mode index>]<mode>[-<vrefresh>][@<format>]
Above application with the syntax provides the frame to Primary plane.
To list the connector, CRTC and plane information for the platform, below command helps.
modetest -M synaptics
SL1680 Display
SL1680, default configuration provides Encoders – 2, connectors – 2,
planes – 4 (MAIN, PIP, GFX1 and GFX2)
Sample output of command modetest -M synaptics is as below:
Encoders:
id crtc type possible crtcs possible clones
38 0 TMDS 0x00000001 0x00000001
40 0 DPI 0x00000002 0x00000002
Connectors:
id encoder status name size (mm) modes encoders
37 0 connected HDMI-A-1 0x0 2 38
modes:
index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
#0 1920x1080 60.00 1920 2008 2052 2200 1080 1084 1089 1125 148500 flags: nhsync, nvsync; type: preferred, driver
#1 1280x720 60.00 1280 1390 1430 1650 720 725 730 750 74250 flags: phsync, pvsync; type: driver
props:
1 EDID:
flags: immutable blob
blobs:
value:
2 DPMS:
flags: enum
enums: On=0 Standby=1 Suspend=2 Off=3
value: 3
5 link-status:
flags: enum
enums: Good=0 Bad=1
value: 0
6 non-desktop:
flags: immutable range
values: 0 1
value: 0
4 TILE:
flags: immutable blob
blobs:
value:
39 0 connected DSI-1 0x0 1 40
modes:
index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
#0 800x1280 60.05 800 860 892 952 1280 1296 1298 1312 75000 flags: ; type: preferred, driver
props:
1 EDID:
flags: immutable blob
blobs:
value:
2 DPMS:
flags: enum
enums: On=0 Standby=1 Suspend=2 Off=3
value: 3
5 link-status:
flags: enum
enums: Good=0 Bad=1
value: 0
6 non-desktop:
flags: immutable range
values: 0 1
value: 0
4 TILE:
flags: immutable blob
blobs:
value:
CRTCs:
id fb pos size
35 0 (0,0) (0x0)
#0 nan 0 0 0 0 0 0 0 0 0 flags: ; type:
props:
24 VRR_ENABLED:
flags: range
values: 0 1
value: 0
36 0 (0,0) (0x0)
#0 nan 0 0 0 0 0 0 0 0 0 flags: ; type:
props:
24 VRR_ENABLED:
flags: range
values: 0 1
value: 0
Planes:
id crtc fb CRTC x,y x,y gamma size possible crtcs
31 0 0 0,0 0,0 0 0x00000003
formats: NV12 NV21 UYVY VYUY YUYV YVYU
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 0
32 0 0 0,0 0,0 0 0x00000003
formats: XR24 AR24 XB24 AB24 NV12 NV21
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 1
33 0 0 0,0 0,0 0 0x00000003
formats: XR24 AR24 XB24 AB24
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 1
34 0 0 0,0 0,0 0 0x00000003
formats: XR24 AR24 XB24 AB24
props:
8 type:
flags: immutable enum
enums: Overlay=0 Primary=1 Cursor=2
value: 0
Frame buffers:
id size pitch
Single Display Mode (HDMI only)
Push frame to GFX1 plane using below modetest command.
modetest -M synaptics -s 37@35:1920x1080@AR24
Push frame to both GFX1 and PIP plane using below modetest command.
modetest -M synaptics -s 37@35:1920x1080@AR24 -P 32@37:1920x1080@AR24
Dual Display Mode (HDMI + MIPI-DSI)
Push frame to GFX1 plane (Display on HDMI) using below modetest command.
modetest -M synaptics -s 37@35:1920x1080@AR24
Push frame to PIP plane (Display on DSI) using below modetest command.
modetest -M synaptics -s 39@36:800x1280@AR24
SL1640 Display
SL1640 Supports: Encoder – 1; CRTC – 1; Planes – 2 (MAIN and GFX1 planes)
Single Display (HDMI only)
Push frame to GFX1 plane using below modetest command.
modetest -M synaptics -s 36@35:1920x1080@AR24
Single Display (MIPI-DSI only)
Push frame to GFX1 plane using below modetest command.
modetest -M synaptics -s 36@35:800x1280@AR24
SL1620 Display
Default list of connector/mode details in SL1620 is as below:
Encoders:
id crtc type possible crtcs possible clones
35 0 DPI 0x00000001 0x00000001
37 0 DSI 0x00000002 0x00000002
Connectors:
id encoder status name size (mm) modes encoders
36 0 connected DPI-1 0x0 1 35
modes:
index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
#0 800x480 59.72 800 1010 1012 1058 480 502 504 527 33300 flags: ; type: preferred, driver
…
…
38 0 connected DPI-2 0x0 1 37
modes:
index name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot
#0 800x1280 60.05 800 860 892 952 1280 1296 1298 1312 75000 flags: ; type: preferred, driver
…
…
TFT Display
Push frame to TFT display using below modetest command.
modetest -M synaptics -s 36@33:800x480@AR24
MIPI-DSI Display
Push frame to MIPI-DSI display using below modetest command.
modetest -M synaptics -s 38@34:800x1280@AR24