[PATCH] drm/i915/display/vlv_dsi: Do no shut down displays on reboot if a DSI panel is used

[Hans de Goede]

Hi,

On 3/1/21 4:43 PM, Hans de Goede wrote:
> After the recently added commit fe0f1e3bfdfe ("drm/i915: Shut down
> displays gracefully on reboot"), the DSI panel on a Cherry Trail based
> Predia Basic tablet would no longer properly light up after reboot.
> 
> The backlight still turns back on after reboot, but the LCD shows an
> all black display. The display is also all black during the time that
> EFI / the GOP is managing it, so e.g. the grub menu also is not visible.
> 
> In this scenario the panel is initialized so that it appears to be working
> and the fastboot code skips doing a modeset. Forcing a modeset by doing a
> chvt to a text-console over ssh followed by echo-ing 1 and then 0 to
> /sys/class/graphics/fb0/blank causes the panel to work again.
> 
> Add a QUIRK_SKIP_SHUTDOWN quirk which turns i915_driver_shutdown() into
> a no-op when set; and set this on vlv/chv devices when a DSI panel is
> detected, to work around this.
> 
> Admittedly this is a bit of a big hammer, but these platforms have been
> around for quite some time now and they have always worked fine without
> the new behavior to shutdown everything on shutdown/reboot. This approach
> simply disables the recently introduced new shutdown behavior in this
> specific case where it is known to cause problems. Which is a nice and
> simple way to deal with this.
> 
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>

Ping? Since sending this patch I've been seeing the issue addressed by
this on variour other CHT based devices too.

So we have various devices suffering from a black screen after reboot
now. This is pretty serious usability regression.

As such it would be good to get this reviewed, or another fix proposed.

Regards,

Hans



> ---
>  drivers/gpu/drm/i915/display/vlv_dsi.c | 3 +++
>  drivers/gpu/drm/i915/i915_drv.c        | 3 +++
>  drivers/gpu/drm/i915/i915_drv.h        | 1 +
>  3 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/vlv_dsi.c b/drivers/gpu/drm/i915/display/vlv_dsi.c
> index f94025ec603a..792ef868b6af 100644
> --- a/drivers/gpu/drm/i915/display/vlv_dsi.c
> +++ b/drivers/gpu/drm/i915/display/vlv_dsi.c
> @@ -1949,6 +1949,9 @@ void vlv_dsi_init(struct drm_i915_private *dev_priv)
>  
>  	vlv_dsi_add_properties(intel_connector);
>  
> +	/* Some BIOS-es fail to re-init the DSI panel on reboot if we turn it off */
> +	dev_priv->quirks |= QUIRK_SKIP_SHUTDOWN;
> +
>  	return;
>  
>  err_cleanup_connector:
> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> index 8e9cb44e66e5..92f2af55af6d 100644
> --- a/drivers/gpu/drm/i915/i915_drv.c
> +++ b/drivers/gpu/drm/i915/i915_drv.c
> @@ -1048,6 +1048,9 @@ static void intel_shutdown_encoders(struct drm_i915_private *dev_priv)
>  
>  void i915_driver_shutdown(struct drm_i915_private *i915)
>  {
> +	if (i915->quirks & QUIRK_SKIP_SHUTDOWN)
> +		return;
> +
>  	disable_rpm_wakeref_asserts(&i915->runtime_pm);
>  
>  	i915_gem_suspend(i915);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 26d69d06aa6d..272cd7cb22d4 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -517,6 +517,7 @@ struct i915_psr {
>  #define QUIRK_PIN_SWIZZLED_PAGES (1<<5)
>  #define QUIRK_INCREASE_T12_DELAY (1<<6)
>  #define QUIRK_INCREASE_DDI_DISABLED_TIME (1<<7)
> +#define QUIRK_SKIP_SHUTDOWN (1<<8)
>  
>  struct intel_fbdev;
>  struct intel_fbc_work;
>