* [PATCH] ARM: dts: rockchip: Use interpolated brightness tables for veyron
@ 2019-10-01 23:07 Matthias Kaehlcke
2019-10-02 22:23 ` Doug Anderson
0 siblings, 1 reply; 3+ messages in thread
From: Matthias Kaehlcke @ 2019-10-01 23:07 UTC (permalink / raw)
To: Heiko Stuebner, Rob Herring, Mark Rutland
Cc: Douglas Anderson, Matthias Kaehlcke, devicetree, linux-kernel,
linux-rockchip, linux-arm-kernel
Use interpolated brightness tables (added by commit 573fe6d1c25
("backlight: pwm_bl: Linear interpolation between
brightness-levels") for veyron, instead of specifying every single
step.
Another option would be to switch to a perceptual brightness curve
(CIE 1931), with the caveat that it would change the behavior of
the backlight. Also the concept of a minimum brightness level is
currently not supported for CIE 1931 curves.
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
---
arch/arm/boot/dts/rk3288-veyron-edp.dtsi | 35 ++--------------------
arch/arm/boot/dts/rk3288-veyron-jaq.dts | 35 ++--------------------
arch/arm/boot/dts/rk3288-veyron-minnie.dts | 35 ++--------------------
arch/arm/boot/dts/rk3288-veyron-tiger.dts | 35 ++--------------------
4 files changed, 8 insertions(+), 132 deletions(-)
diff --git a/arch/arm/boot/dts/rk3288-veyron-edp.dtsi b/arch/arm/boot/dts/rk3288-veyron-edp.dtsi
index 773bedca872f..e95c89fe0545 100644
--- a/arch/arm/boot/dts/rk3288-veyron-edp.dtsi
+++ b/arch/arm/boot/dts/rk3288-veyron-edp.dtsi
@@ -41,39 +41,8 @@
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>;
+ brightness-levels = <0 255>;
+ num-interpolated-steps = <254>;
default-brightness-level = <128>;
enable-gpios = <&gpio7 RK_PA2 GPIO_ACTIVE_HIGH>;
pinctrl-names = "default";
diff --git a/arch/arm/boot/dts/rk3288-veyron-jaq.dts b/arch/arm/boot/dts/rk3288-veyron-jaq.dts
index 56ad9a43a6c2..5e10cc644875 100644
--- a/arch/arm/boot/dts/rk3288-veyron-jaq.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-jaq.dts
@@ -21,39 +21,8 @@
&backlight {
/* Jaq panel PWM must be >= 3%, so start non-zero brightness at 8 */
- brightness-levels = <
- 0
- 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>;
+ brightness-levels = <8 255>;
+ num-interpolated-steps = <246>;
};
&rk808 {
diff --git a/arch/arm/boot/dts/rk3288-veyron-minnie.dts b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
index 6b0e1cb1f681..503278e60d6b 100644
--- a/arch/arm/boot/dts/rk3288-veyron-minnie.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
@@ -39,39 +39,8 @@
&backlight {
/* Minnie panel PWM must be >= 1%, so start non-zero brightness at 3 */
- brightness-levels = <
- 0 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>;
+ brightness-levels = <3 255>;
+ num-interpolated-steps = <251>;
};
&i2c_tunnel {
diff --git a/arch/arm/boot/dts/rk3288-veyron-tiger.dts b/arch/arm/boot/dts/rk3288-veyron-tiger.dts
index 27557203ae33..e50367564dc6 100644
--- a/arch/arm/boot/dts/rk3288-veyron-tiger.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-tiger.dts
@@ -23,39 +23,8 @@
&backlight {
/* Tiger panel PWM must be >= 1%, so start non-zero brightness at 3 */
- brightness-levels = <
- 0 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>;
+ brightness-levels = <3 255>;
+ num-interpolated-steps = <251>;
};
&backlight_regulator {
--
2.23.0.444.g18eeb5a265-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ARM: dts: rockchip: Use interpolated brightness tables for veyron
2019-10-01 23:07 [PATCH] ARM: dts: rockchip: Use interpolated brightness tables for veyron Matthias Kaehlcke
@ 2019-10-02 22:23 ` Doug Anderson
2019-10-02 23:44 ` Matthias Kaehlcke
0 siblings, 1 reply; 3+ messages in thread
From: Doug Anderson @ 2019-10-02 22:23 UTC (permalink / raw)
To: Matthias Kaehlcke
Cc: Heiko Stuebner, Rob Herring, Mark Rutland, devicetree, LKML,
open list:ARM/Rockchip SoC...,
Linux ARM
Hi,
On Tue, Oct 1, 2019 at 4:07 PM Matthias Kaehlcke <mka@chromium.org> wrote:
> --- a/arch/arm/boot/dts/rk3288-veyron-minnie.dts
> +++ b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
> @@ -39,39 +39,8 @@
>
> &backlight {
> /* Minnie panel PWM must be >= 1%, so start non-zero brightness at 3 */
> - brightness-levels = <
> - 0 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>;
> + brightness-levels = <3 255>;
> + num-interpolated-steps = <251>;
I _think_ you want:
brightness-levels = <0 3 255>;
num-interpolated-steps = <252>;
Specifically:
* It seems like you're intending to keep everything the same and just
have a more compact representation, right? Looking through the values
in '/sys/class/backlight/backlight' on minnie shows differences before
and after your patch.
* I think you want brightness of 0 to match to PWM level 0.
* If I put in printouts in the code with your table, I see:
pwm-backlight backlight: new number of brightness levels: 252
pwm-backlight backlight: i=0, j=0, lc=0, value=3
pwm-backlight backlight: i=0, j=1, lc=1, value=4
...
pwm-backlight backlight: i=0, j=250, lc=250, value=253
pwm-backlight backlight: lc=251, data->levels[i]=255
...as you can see, you end up missing assigning a value of 254.
-Doug
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ARM: dts: rockchip: Use interpolated brightness tables for veyron
2019-10-02 22:23 ` Doug Anderson
@ 2019-10-02 23:44 ` Matthias Kaehlcke
0 siblings, 0 replies; 3+ messages in thread
From: Matthias Kaehlcke @ 2019-10-02 23:44 UTC (permalink / raw)
To: Doug Anderson
Cc: Heiko Stuebner, Rob Herring, Mark Rutland, devicetree, LKML,
open list:ARM/Rockchip SoC...,
Linux ARM
On Wed, Oct 02, 2019 at 03:23:54PM -0700, Doug Anderson wrote:
> Hi,
>
> On Tue, Oct 1, 2019 at 4:07 PM Matthias Kaehlcke <mka@chromium.org> wrote:
> > --- a/arch/arm/boot/dts/rk3288-veyron-minnie.dts
> > +++ b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
> > @@ -39,39 +39,8 @@
> >
> > &backlight {
> > /* Minnie panel PWM must be >= 1%, so start non-zero brightness at 3 */
> > - brightness-levels = <
> > - 0 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>;
> > + brightness-levels = <3 255>;
> > + num-interpolated-steps = <251>;
>
> I _think_ you want:
>
> brightness-levels = <0 3 255>;
> num-interpolated-steps = <252>;
>
> Specifically:
>
> * It seems like you're intending to keep everything the same and just
> have a more compact representation, right?
Ideally yes, I thought we were missing 1 level due to the 0 step being
missing, but it's actually 2, since I interpreted 'num-interpolated-steps'
as the number between two values in the table, however it is this number +1.
> Looking through the values in '/sys/class/backlight/backlight' on
> minnie shows differences before and after your patch.
>
> * I think you want brightness of 0 to match to PWM level 0.
For level 0 that was actually given, due to
pwm_backlight_update_status()
{
..
if (brightness > 0) {
...
} else
pwm_backlight_power_off(pb);
...
}
but we're slightly off for the rest of the levels.
> * If I put in printouts in the code with your table, I see:
>
> pwm-backlight backlight: new number of brightness levels: 252
> pwm-backlight backlight: i=0, j=0, lc=0, value=3
> pwm-backlight backlight: i=0, j=1, lc=1, value=4
> ...
> pwm-backlight backlight: i=0, j=250, lc=250, value=253
> pwm-backlight backlight: lc=251, data->levels[i]=255
>
> ...as you can see, you end up missing assigning a value of 254.
Thanks for investigating. With 'num-interpolated-steps' increased
by one this is fixed, though we are still missing one level at the
beginning of the table. I didn't expect 'brightness-levels = <0 3 255>'
to work, since there are less than 252/251 integer numbers between 0
and 3, but the code actually accounts for that case and just interprets
it as a single step, which is what we want.
Long story short: you are right, we want
brightness-levels = <0 3 255>;
num-interpolated-steps = <252>;
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-10-01 23:07 [PATCH] ARM: dts: rockchip: Use interpolated brightness tables for veyron Matthias Kaehlcke
2019-10-02 22:23 ` Doug Anderson
2019-10-02 23:44 ` Matthias Kaehlcke
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