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SubjectRe: [PATCH 5/5] drm/i915/dsi: Control panel and backlight enable GPIOs on BYT
On Sun, Dec 15, 2019 at 5:38 PM Hans de Goede <> wrote:

> On Bay Trail devices the MIPI power on/off sequences for DSI LCD panels
> do not control the LCD panel- and backlight-enable GPIOs. So far, when
> the VBT indicates we should use the SoC for backlight control, we have
> been relying on these GPIOs being configured as output and driven high by
> the Video BIOS (GOP) when it initializes the panel.
> This does not work when the device is booted with a HDMI monitor connected
> as then the GOP will initialize the HDMI instead of the panel, leaving the
> panel black, even though the i915 driver tries to output an image to it.
> Likewise on some device-models when the GOP does not initialize the DSI
> panel it also leaves the mux of the PWM0 pin in generic GPIO mode instead
> of muxing it to the PWM controller.
> This commit makes the DSI code control the SoC GPIOs for panel- and
> backlight-enable on BYT, when the VBT indicates the SoC should be used
> for backlight control. It also ensures that the PWM0 pin is muxed to the
> PWM controller in this case.
> This fixes the LCD panel not lighting up on various devices when booted
> with a HDMI monitor connected. This has been tested to fix this on the
> following devices:
> Peaq C1010
> Point of View MOBII TAB-P800W
> Point of View MOBII TAB-P1005W
> Terra Pad 1061
> Yours Y8W81
> Signed-off-by: Hans de Goede <>

Looks good to me:
Reviewed-by: Linus Walleij <>

Linus Walleij

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