refactor(core): refactoring the function calls of display backlight driver in RUST so that the u16 data types have been converted to u8 ones. The code has been reviewed whether it's safe - no problems detected.

diff --git a/core/embed/rust/src/ui/layout_bolt/component/number_input_slider.rs b/core/embed/rust/src/ui/layout_bolt/component/number_input_slider.rs
index e652f8ec..7b40a4b0 100644
--- a/core/embed/rust/src/ui/layout_bolt/component/number_input_slider.rs
+++ b/core/embed/rust/src/ui/layout_bolt/component/number_input_slider.rs
@@ -9,7 +9,7 @@ use crate::ui::{
 use super::{theme, Button, ButtonMsg};
 
 pub enum NumberInputSliderDialogMsg {
-    Changed(u16),
+    Changed(u8),
     Confirmed,
     Cancelled,
 }
@@ -22,7 +22,8 @@ pub struct NumberInputSliderDialog {
 }
 
 impl NumberInputSliderDialog {
-    pub fn new(min: u16, max: u16, init_value: u16) -> Self {
+    pub fn new(min: u8, max: u8, init_value: u8) -> Self {
+        debug_assert!(min < max);
         Self {
             area: Rect::zero(),
             input: NumberInputSlider::new(min, max, init_value).into_child(),
@@ -35,7 +36,7 @@ impl NumberInputSliderDialog {
         }
     }
 
-    pub fn value(&self) -> u16 {
+    pub fn value(&self) -> u8 {
         self.input.inner().value
     }
 }
@@ -91,13 +92,13 @@ impl crate::trace::Trace for NumberInputSliderDialog {
 pub struct NumberInputSlider {
     area: Rect,
     touch_area: Rect,
-    min: u16,
-    max: u16,
-    value: u16,
+    min: u8,
+    max: u8,
+    value: u8,
 }
 
 impl NumberInputSlider {
-    pub fn new(min: u16, max: u16, value: u16) -> Self {
+    pub fn new(min: u8, max: u8, value: u8) -> Self {
         let value = value.clamp(min, max);
         Self {
             area: Rect::zero(),
@@ -108,12 +109,12 @@ impl NumberInputSlider {
         }
     }
 
-    pub fn slider_eval(&mut self, pos: Point, ctx: &mut EventCtx) -> Option<u16> {
+    pub fn slider_eval(&mut self, pos: Point, ctx: &mut EventCtx) -> Option<u8> {
         if self.touch_area.contains(pos) {
             let filled = pos.x - self.area.x0;
             let filled = filled.clamp(0, self.area.width());
             let val_pct = (filled as u16 * 100) / self.area.width() as u16;
-            let val = (val_pct * (self.max - self.min)) / 100 + self.min;
+            let val = ((val_pct * (self.max - self.min) as u16) / 100) as u8 + self.min;
 
             if val != self.value {
                 self.value = val;
@@ -126,7 +127,7 @@ impl NumberInputSlider {
 }
 
 impl Component for NumberInputSlider {
-    type Msg = u16;
+    type Msg = u8;
 
     fn place(&mut self, bounds: Rect) -> Rect {
         self.area = bounds;
@@ -146,7 +147,7 @@ impl Component for NumberInputSlider {
     }
 
     fn render<'s>(&'s self, target: &mut impl Renderer<'s>) {
-        let val_pct = (100 * (self.value - self.min)) / (self.max - self.min);
+        let val_pct = (100 * (self.value - self.min) as u16) / (self.max - self.min) as u16;
 
         shape::Bar::new(self.area)
             .with_radius(2)
diff --git a/core/embed/rust/src/ui/layout_bolt/component/set_brightness.rs b/core/embed/rust/src/ui/layout_bolt/component/set_brightness.rs
index 3f9075ae..dd644f29 100644
--- a/core/embed/rust/src/ui/layout_bolt/component/set_brightness.rs
+++ b/core/embed/rust/src/ui/layout_bolt/component/set_brightness.rs
@@ -19,9 +19,9 @@ pub struct SetBrightnessDialog(NumberInputSliderDialog);
 impl SetBrightnessDialog {
     pub fn new(current: u8) -> Self {
         Self(NumberInputSliderDialog::new(
-            theme::backlight::get_backlight_min().into(),
-            theme::backlight::get_backlight_max().into(),
-            current.into(),
+            theme::backlight::get_backlight_min(),
+            theme::backlight::get_backlight_max(),
+            current,
         ))
     }
 }
@@ -36,15 +36,7 @@ impl Component for SetBrightnessDialog {
     fn event(&mut self, ctx: &mut EventCtx, event: Event) -> Option<Self::Msg> {
         match self.0.event(ctx, event) {
             Some(NumberInputSliderDialogMsg::Changed(value)) => {
-                // TODO: needs more analysis; why is "value" u16? Can it be changed to u8?
-                // Original code: display::set_backlight(value.into());
-                // Possible solution: display::set_backlight(value.try_into().unwrap());
-                // It's not save. To rather use unwrap!() macro? Another solution below.
-                if let Ok(val) = value.try_into() {
-                    display::set_backlight(val);
-                } else {
-                    display::set_backlight(255);
-                }
+                display::set_backlight(value);
                 None
             }
             Some(NumberInputSliderDialogMsg::Cancelled) => Some(CancelConfirmMsg::Cancelled),
diff --git a/core/embed/rust/src/ui/layout_eckhart/firmware/brightness_screen.rs b/core/embed/rust/src/ui/layout_eckhart/firmware/brightness_screen.rs
index 59598a54..371111f1 100644
--- a/core/embed/rust/src/ui/layout_eckhart/firmware/brightness_screen.rs
+++ b/core/embed/rust/src/ui/layout_eckhart/firmware/brightness_screen.rs
@@ -25,7 +25,7 @@ pub struct SetBrightnessScreen {
 
 impl SetBrightnessScreen {
     const SLIDER_HEIGHT: i16 = 392;
-    pub fn new(min: u16, max: u16, init_value: u16) -> Self {
+    pub fn new(min: u8, max: u8, init_value: u8) -> Self {
         Self {
             header: Header::new(TR::brightness__title.into()).with_right_button(
                 Button::with_icon(theme::ICON_CHECKMARK).styled(theme::button_header()),
@@ -87,17 +87,17 @@ impl crate::trace::Trace for SetBrightnessScreen {
 struct VerticalSlider {
     area: Rect,
     touch_area: Rect,
-    min: u16,
-    max: u16,
-    value: u16,
-    val_pct: u16,
+    min: u8,
+    max: u8,
+    value: u8,
+    val_pct: u8,
     touching: bool,
 }
 
 impl VerticalSlider {
     const SLIDER_WIDTH: i16 = 120;
 
-    pub fn new(min: u16, max: u16, value: u16) -> Self {
+    pub fn new(min: u8, max: u8, value: u8) -> Self {
         debug_assert!(min < max);
         let value = value.clamp(min, max);
         Self {
@@ -113,15 +113,7 @@ impl VerticalSlider {
 
     fn handle_touch(&mut self, pos: Point, ctx: &mut EventCtx) {
         self.update_value(pos, ctx);
-        // TODO: needs more analysis; why is "self.value" u16? Can it be changed to u8?
-        // Original code: display::set_backlight(self.value.into());
-        // Possible solution: display::set_backlight(self.value.try_into().unwrap());
-        // It's not save. To rather use unwrap!() macro? Another solution below.
-        if let Ok(val) = self.value.try_into() {
-            display::set_backlight(val);
-        } else {
-            display::set_backlight(255);
-        }
+        display::set_backlight(self.value);
         ctx.request_paint();
     }
 
@@ -136,7 +128,7 @@ impl VerticalSlider {
 
         let filled = (proportional_area.y1 - pos.y).clamp(0, proportional_area.height());
         let val_pct = (filled as u16 * 100) / proportional_area.height() as u16;
-        let val = (val_pct * (self.max - self.min)) / 100 + self.min;
+        let val = ((val_pct * (self.max - self.min) as u16) / 100) as u8 + self.min;
 
         if val != self.value {
             ctx.request_paint();
@@ -184,7 +176,8 @@ impl Component for VerticalSlider {
     }
 
     fn render<'s>(&'s self, target: &mut impl Renderer<'s>) {
-        let val_pct = ((100 * (self.value - self.min)) / (self.max - self.min)).clamp(0, 100);
+        let val_pct =
+            ((100 * (self.value - self.min) as u16) / (self.max - self.min) as u16).clamp(0, 100);
 
         // Square area for the slider
         let (_, small_area) = self.area.split_bottom(Self::SLIDER_WIDTH);
diff --git a/core/embed/rust/src/ui/layout_eckhart/ui_firmware.rs b/core/embed/rust/src/ui/layout_eckhart/ui_firmware.rs
index 4eba7684..18cff5ec 100644
--- a/core/embed/rust/src/ui/layout_eckhart/ui_firmware.rs
+++ b/core/embed/rust/src/ui/layout_eckhart/ui_firmware.rs
@@ -1051,12 +1051,12 @@ impl FirmwareUI for UIEckhart {
                 // Set the brightness immediately so it is applied in the `_first_paint` UI
                 // layout function
                 unwrap!(storage::set_brightness(value));
-                value.into()
+                value
             }
-            None => theme::backlight::get_backlight_normal().into(),
+            None => theme::backlight::get_backlight_normal(),
         };
-        let min = theme::backlight::get_backlight_min().into();
-        let max = theme::backlight::get_backlight_max().into();
+        let min = theme::backlight::get_backlight_min();
+        let max = theme::backlight::get_backlight_max();
 
         let screen = SetBrightnessScreen::new(min, max, init_value);
         let layout = RootComponent::new(screen);