[PATCH v2 1/2] drm/exynos: Fix DSI resuming fail because power domain being off

[inki.dae@samsung.com (Inki Dae)]

On 2014? 11? 07? 22:53, Krzysztof Kozlowski wrote:
> During system resume from suspend to RAM the Exynos DRM driver forced
> CRTC mode thus turning display on (DPMS_ON). This lead to runtime resuming
> of DSI which failed because whole LCD power domain was off and it was
> not allowed to turn on because of system resume in progress.
> 
> Forcing mode should not be needed and removing it solves this particular
> problem.

only this patch, Applied.

Thanks,
Inki Dae

> 
> This necessary fix for following scenario reproduced on Exynos DRM:
> 1. Power domain is off before suspending the system.
> 2. System is suspended to RAM.
> 3. Resuming starts. The Exynos DRM driver resume callback is called.
> 4. The Exynos DRM driver calls drm_helper_resume_force_mode() which turns
>    on the screen by calling exynos_dsi_dpms with DRM_MODE_DPMS_ON.
> 5. The Exynos DSI driver calls pm_runtime_get. The driver runtime
>    resumes and this should turn LCD power domain on.
> 6. Unfortunately the domain cannot be turned on because system resume is
>    in progress and genpd->prepared_count is positive.
> 
> Steps to reproduce:
> 1. Add runtime PM to Exynos DSI driver.
> 2. Build Exynos DRM/FB without FRAMEBUFFER_CONSOLE.
> 3. Enable the connector and screen (e.g. with modeset-vsync).
> 4. echo 3 > /sys/devices/platform/exynos-drm/graphics/fb0/blank
> 5. echo mem > /sys/power/state
> 6. Resume.
> [   77.712469] PM: early resume of devices complete after 3.854 msecs
> [   77.712739] exynos-dsi 11c80000.dsi: pm_genpd_resume()
> [   77.712758] exynos4-fimc 11800000.fimc: pm_genpd_resume()
> [   77.712774] exynos4-fimc 11810000.fimc: pm_genpd_resume()
> [   77.712787] exynos-drm-fimc 11820000.fimc: pm_genpd_resume()
> [   77.712802] exynos-drm-fimc 11830000.fimc: pm_genpd_resume()
> [   77.712815] s5p-mipi-csis 11880000.csis: pm_genpd_resume()
> [   77.712829] s5p-mipi-csis 11890000.csis: pm_genpd_resume()
> [   77.712843] exynos-fimc-lite 12390000.fimc-lite: pm_genpd_resume()
> [   77.712856] exynos-fimc-lite 123a0000.fimc-lite: pm_genpd_resume()
> [   77.713788] exynos4-fb 11c00000.fimd: pm_genpd_resume()
> [   77.713912] wake disabled for irq 184
> [   77.713923] wake disabled for irq 185
> [   77.714082] wake disabled for irq 173
> [   77.715676] wake disabled for irq 176
> [   77.718540] exynos4-fb 11c00000.fimd: pm_genpd_runtime_resume()
> [   77.718567] exynos4-fb 11c00000.fimd: state restore latency exceeded, new value 1708 ns
> [   77.718636] exynos-dsi 11c80000.dsi: pm_genpd_runtime_resume()
> [   77.892366] exynos-dsi 11c80000.dsi: PLL failed to stabilize
> [   77.892377] exynos-dsi 11c80000.dsi: failed to configure DSI PLL
> [   78.192168] exynos-dsi 11c80000.dsi: timeout waiting for reset
> [   78.211578] exynos-dsi 11c80000.dsi: waiting for bus lanes timed out
> [   78.307173] exynos-dsi 11c80000.dsi: xfer timed out: d1 00 (null)
> [   78.307190] panel_s6e8aa0 11c80000.dsi.0: error -110 reading dcs seq(0xd1)
> [   78.307199] panel_s6e8aa0 11c80000.dsi.0: read id failed
> 
> Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
> ---
>  drivers/gpu/drm/exynos/exynos_drm_drv.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_drm_drv.c b/drivers/gpu/drm/exynos/exynos_drm_drv.c
> index d32165a7f862..8f7110c9d21f 100644
> --- a/drivers/gpu/drm/exynos/exynos_drm_drv.c
> +++ b/drivers/gpu/drm/exynos/exynos_drm_drv.c
> @@ -200,8 +200,6 @@ static int exynos_drm_resume(struct drm_device *dev)
>  	}
>  	drm_modeset_unlock_all(dev);
>  
> -	drm_helper_resume_force_mode(dev);
> -
>  	return 0;
>  }
>  
>