On 01/05/2019 15:09, Jagan Teki wrote:
On Wed, May 1, 2019 at 6:17 PM Robin Murphy <robin.murphy@xxxxxxx> wrote:
On 01/05/2019 13:14, Jagan Teki wrote:
FriendlyELEC HD702E is one of optional LCD panel for
NanoPC T4 eDP interface.
It features 800x1280 resolutions, with built in GT9271 captive
touchscreen and adjustable backlight via PWM.
eDP panel connections are:
- VCC3V3_SYS: 3.3V panel power supply
- GPIO4_C2: PWM0_BL pin
- GPIO4_D5_LCD_BL_EN: Backlight enable pin
- VCC12V0_SYS: 12V backlight power supply
- Touchscreen connected via I2C4
- GPIO1_C4_TP_INT: touchscreen interrupt pin
- GPIO1_B5_TP_RST: touchscreen reset pin
Add support for it.
Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx>
---
Note: we need to disable hdmi-cec pinctrl to work with
edp-hpd since both share same pin, otherwise we can
encounter below error during bootup
[ 1.047726] rockchip-pinctrl pinctrl: pin gpio4-23 already requested by ff940000.hdmi; cannot claim for ff970000.edp
[ 1.048655] rockchip-pinctrl pinctrl: pin-151 (ff970000.edp) status -22
[ 1.049235] rockchip-pinctrl pinctrl: could not request pin 151 (gpio4-23) from group edp-hpd on device rockchip-pinctrl
[ 1.050191] rockchip-dp ff970000.edp: Error applying setting, reverse things back
[ 1.050867] rockchip-dp: probe of ff970000.edp failed with error -22
Hmm, AFAICS that pin is exclusively wired to the HDMI connector and not
used for the eDP interface, so really it's the fault of rk3399.dtsi for
trying to claim it unconditionally. Ideally we'd pull those pinctrl
properties out into the board DTs which do actually need them, but the
quick and easy approach would be to add some "/delete-property/ ..."
workarounds to the &edp node here.
Thought that initially, but the same pin shared between HDMI CEC and
eDP hotplug with different bit function to enable.
gpio4c7_sel
GPIO4C[7] iomux select
2'b00: gpio
2'b01: hdmi_cecinout
2'b10: edp_hotplug
2'b11: reserved
GPIO4_C7/HDMI_CECINOUT/EDP_HOTPLUG is the shared pin, which is
available in any nanopc-t4 as well in rk3399 datasheet, look like it's
an SoC pin that driver hotplug to eDP and ie same reason is pinmux in
rk3399.dtsi.
I event removed edp_hpd pinctrl from edp node in rk3399.dtsi, but
display not appear on the screen and observed edp bridge issue on
host.
Ah, I see - from a quick scan through the drivers it looks the
"force-hpd" property already exists as the solution for that. Either way
I don't think it would be safe to rely on the EDP_HOTPLUG pinctrl
appearing to work, given that the physical pin is hard-wired to the HDMI
connector - presumably if you tried to use the eDP display while a TV is
plugged in and periodically sending CEC messages, all kinds of
shenanigans might ensue.
[ 1.052191] rockchip-drm display-subsystem: bound ff8f0000.vop (ops
vop_component_ops)
[ 1.054460] rockchip-drm display-subsystem: bound ff900000.vop (ops
vop_component_ops)
[ 1.055214] rockchip-dp ff970000.edp: no DP phy configured
[ 1.056088] rockchip-drm display-subsystem: bound ff970000.edp (ops
rockchip_dp_component_ops)
[ 1.056852] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 1.057449] [drm] No driver support for vblank timestamp query.
[ 1.174379] [drm:analogix_dp_bridge_enable] *ERROR* failed to get
hpd single ret = -110
[ 1.174408] rockchip-dp ff970000.edp: failed to set bridge, retry: 0
[ 1.285524] [drm:analogix_dp_bridge_enable] *ERROR* failed to get
hpd single ret = -110
[ 1.285539] rockchip-dp ff970000.edp: failed to set bridge, retry: 1
[ 1.355241] dwmmc_rockchip fe310000.dwmmc: Successfully tuned phase to 212
[ 1.358757] mmc0: new ultra high speed SDR104 SDIO card at address 0001
[ 1.397049] [drm:analogix_dp_bridge_enable] *ERROR* failed to get
hpd single ret = -110
[ 1.397069] rockchip-dp ff970000.edp: failed to set bridge, retry: 2
[ 1.485582] dwmmc_rockchip fe320000.dwmmc: Successfully tuned phase to 220
[ 1.485590] mmc1: new ultra high speed SDR104 SDHC card at address 084e
[ 1.486246] mmcblk1: mmc1:084e R04GS 3.71 GiB
[ 1.488032] mmcblk1: p1
[ 1.509088] [drm:analogix_dp_bridge_enable] *ERROR* failed to get
hpd single ret = -110
[ 1.509119] rockchip-dp ff970000.edp: failed to set bridge, retry: 3
[ 1.620938] [drm:analogix_dp_bridge_enable] *ERROR* failed to get
hpd single ret = -110
[ 1.620953] rockchip-dp ff970000.edp: failed to set bridge, retry: 4
[ 1.620970] rockchip-dp ff970000.edp: too many times retry set
bridge, give it up
[ 1.644026] Console: switching to colour frame buffer device 100x80
.../boot/dts/rockchip/rk3399-nanopc-t4.dts | 82 +++++++++++++++++++
1 file changed, 82 insertions(+)
diff --git a/arch/arm64/boot/dts/rockchip/rk3399-nanopc-t4.dts b/arch/arm64/boot/dts/rockchip/rk3399-nanopc-t4.dts
index 931c3dbf1b7d..b652d960946f 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-nanopc-t4.dts
+++ b/arch/arm64/boot/dts/rockchip/rk3399-nanopc-t4.dts
@@ -46,6 +46,48 @@
};
};
+ backlight: backlight {
+ compatible = "pwm-backlight";
+ brightness-levels = <
+ 0 1 2 3 4 5 6 7
+ 8 9 10 11 12 13 14 15
+ 16 17 18 19 20 21 22 23
+ 24 25 26 27 28 29 30 31
+ 32 33 34 35 36 37 38 39
+ 40 41 42 43 44 45 46 47
+ 48 49 50 51 52 53 54 55
+ 56 57 58 59 60 61 62 63
+ 64 65 66 67 68 69 70 71
+ 72 73 74 75 76 77 78 79
+ 80 81 82 83 84 85 86 87
+ 88 89 90 91 92 93 94 95
+ 96 97 98 99 100 101 102 103
+ 104 105 106 107 108 109 110 111
+ 112 113 114 115 116 117 118 119
+ 120 121 122 123 124 125 126 127
+ 128 129 130 131 132 133 134 135
+ 136 137 138 139 140 141 142 143
+ 144 145 146 147 148 149 150 151
+ 152 153 154 155 156 157 158 159
+ 160 161 162 163 164 165 166 167
+ 168 169 170 171 172 173 174 175
+ 176 177 178 179 180 181 182 183
+ 184 185 186 187 188 189 190 191
+ 192 193 194 195 196 197 198 199
+ 200 201 202 203 204 205 206 207
+ 208 209 210 211 212 213 214 215
+ 216 217 218 219 220 221 222 223
+ 224 225 226 227 228 229 230 231
+ 232 233 234 235 236 237 238 239
+ 240 241 242 243 244 245 246 247
+ 248 249 250 251 252 253 254 255>;
This looks trivial enough that I wonder whether it might still work to
just omit it? Not that I know anything about backlights, but I had the
impression (from mailing list traffic, I guess) that the driver gained
the ability to provide a reasonable default behaviour at some point.
Unaware about this, would you please pass the thread. on the
other-hand I can see sapphire-excavator still using the brightness
levels like this.
It looks like the "default behaviour" thing must have been what ended up
as commit 88ba95bedb79 ("backlight: pwm_bl: Compute brightness of LED
linearly to human eye"). Even if that turns out to be unsuitable for
this particular panel, it seems that the PWM-linear response could now
be specified much more simply as something like:
brightness-levels = <0 255>;
num-interpolated-steps = <256>;
Robin.
