linux-kernel - Re: [PATCH v4 2/8] drm/nouveau: Enable polling even if we have runtime PM

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Date:   Thu, 2 Aug 2018 21:14:05 +0200
From:   Lukas Wunner <lukas@...ner.de>
To:     Lyude Paul <lyude@...hat.com>
Cc:     nouveau@...ts.freedesktop.org,
        Peter Ujfalusi <peter.ujfalusi@...com>, stable@...r.kernel.org,
        Ben Skeggs <bskeggs@...hat.com>,
        David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/8] drm/nouveau: Enable polling even if we have
 runtime PM

On Wed, Aug 01, 2018 at 05:14:52PM -0400, Lyude Paul wrote:
> --- a/drivers/gpu/drm/nouveau/nouveau_drm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
> @@ -592,10 +592,11 @@ nouveau_drm_load(struct drm_device *dev, unsigned long flags)
>  		pm_runtime_allow(dev->dev);
>  		pm_runtime_mark_last_busy(dev->dev);
>  		pm_runtime_put(dev->dev);
> -	} else {
> -		/* enable polling for external displays */
> -		drm_kms_helper_poll_enable(dev);
>  	}
> +
> +	/* enable polling for connectors without hpd */
> +	drm_kms_helper_poll_enable(dev);
> +

I'm wondering why drm_kms_helper_poll_enable() is called here at all.
Does the invocation in nouveau_display_init() not suffice?  Can there
be a situation when nouveau_display_init() is not called despite there
being connectors that need to be polled?

Thanks,

Lukas