[v2] ARM: dts: rockchip: Use interpolated brightness tables for veyron
diff mbox series

Message ID 20191003094137.v2.1.Ic9fd698810ea569c465350154da40b85d24f805b@changeid
State New
Headers show
Series
  • [v2] ARM: dts: rockchip: Use interpolated brightness tables for veyron
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Commit Message

Matthias Kaehlcke Oct. 3, 2019, 4:41 p.m. UTC
Use interpolated brightness tables (added by commit 573fe6d1c25
("backlight: pwm_bl: Linear interpolation between
brightness-levels") for veyron, instead of specifying every single
step. Some devices/panels have intervals that are smaller than
the specified 'num-interpolated-steps', the driver interprets
these intervals as a 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>
---

Changes in v2:
- added 0 as first step for devices/panels that require a minimum
  PWM duty cycle
- increased 'num-interpolated-steps' values by one, it's not the
  number of steps between levels, but that number +1

 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(-)

Comments

Doug Anderson Oct. 8, 2019, 6:05 p.m. UTC | #1
Hi,

On Thu, Oct 3, 2019 at 9:42 AM Matthias Kaehlcke <mka@chromium.org> wrote:
>
> Use interpolated brightness tables (added by commit 573fe6d1c25
> ("backlight: pwm_bl: Linear interpolation between
> brightness-levels") for veyron, instead of specifying every single
> step. Some devices/panels have intervals that are smaller than
> the specified 'num-interpolated-steps', the driver interprets
> these intervals as a 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>
> ---
>
> Changes in v2:
> - added 0 as first step for devices/panels that require a minimum
>   PWM duty cycle
> - increased 'num-interpolated-steps' values by one, it's not the
>   number of steps between levels, but that number +1
>
>  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(-)

I guess if someone wanted to they could try to increase the number of
steps and see if they got prettier backlight transition, but what's
there now doesn't bother me and has the advantage of matching what has
been in use forever.  Thus:

Reviewed-by: Douglas Anderson <dianders@chromium.org>
Heiko Stübner Oct. 10, 2019, 9:23 p.m. UTC | #2
Am Donnerstag, 3. Oktober 2019, 18:41:52 CEST schrieb Matthias Kaehlcke:
> Use interpolated brightness tables (added by commit 573fe6d1c25
> ("backlight: pwm_bl: Linear interpolation between
> brightness-levels") for veyron, instead of specifying every single
> step. Some devices/panels have intervals that are smaller than
> the specified 'num-interpolated-steps', the driver interprets
> these intervals as a 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>

applied for 5.5

Thanks
Heiko

Patch
diff mbox series

diff --git a/arch/arm/boot/dts/rk3288-veyron-edp.dtsi b/arch/arm/boot/dts/rk3288-veyron-edp.dtsi
index b12e061c5f7f..300a7e32c978 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 = <255>;
 		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 80386203e85b..a4966e505a2f 100644
--- a/arch/arm/boot/dts/rk3288-veyron-jaq.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-jaq.dts
@@ -20,39 +20,8 @@ 
 
 &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 = <0 8 255>;
+	num-interpolated-steps = <247>;
 };
 
 &rk808 {
diff --git a/arch/arm/boot/dts/rk3288-veyron-minnie.dts b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
index 55955b082501..c833716dbe48 100644
--- a/arch/arm/boot/dts/rk3288-veyron-minnie.dts
+++ b/arch/arm/boot/dts/rk3288-veyron-minnie.dts
@@ -38,39 +38,8 @@ 
 
 &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 = <0 3 255>;
+	num-interpolated-steps = <252>;
 };
 
 &i2c_tunnel {
diff --git a/arch/arm/boot/dts/rk3288-veyron-tiger.dts b/arch/arm/boot/dts/rk3288-veyron-tiger.dts
index 27557203ae33..bebb230e592f 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 = <0 3 255>;
+	num-interpolated-steps = <252>;
 };
 
 &backlight_regulator {