Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 21 Nov 2018 11:06:16 +0100
From:   Daniel Vetter <daniel@ffwll.ch>
To:     Lyude Paul <lyude@redhat.com>
Cc:     intel-gfx@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Rodrigo Vivi <rodrigo.vivi@intel.com>
Subject: Re: [PATCH] drm/i915: Synchronize hpd work in
 i915_hpd_storm_ctl_show()
Message-ID: <20181121100616.GR4266@phenom.ffwll.local>
Mail-Followup-To: Lyude Paul <lyude@redhat.com>,
        intel-gfx@lists.freedesktop.org, David Airlie <airlied@linux.ie>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        Rodrigo Vivi <rodrigo.vivi@intel.com>
References: <20181121003718.17704-1-lyude@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <20181121003718.17704-1-lyude@redhat.com>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Nov 20, 2018 at 07:37:17PM -0500, Lyude Paul wrote:
> While trying to add a chamelium test for short HPD IRQs, I ran into
> issues where a hotplug storm would be triggered, but the point at which
> it would be reported by the kernel would be after igt actually finished
> checking i915_hpd_storm_ctl's status. So, fix this by simply
> synchronizing our IRQ work, dig_port_work, and hotplug_work before
> printing out the HPD storm status in i915_hpd_storm_ctl_show().
> 
> Signed-off-by: Lyude Paul <lyude@redhat.com>
> Cc: Ville Syrj?l? <ville.syrjala@linux.intel.com>

Makes sense.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 69447c68b9af..af4268a6d2d9 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4592,6 +4592,13 @@ static int i915_hpd_storm_ctl_show(struct seq_file *m, void *data)
>  	struct drm_i915_private *dev_priv = m->private;
>  	struct i915_hotplug *hotplug = &dev_priv->hotplug;
>  
> +	/* Synchronize with everything first in case there's been an HPD
> +	 * storm, but we haven't finished handling it in the kernel yet
> +	 */
> +	synchronize_irq(dev_priv->drm.irq);
> +	flush_work(&dev_priv->hotplug.dig_port_work);
> +	flush_work(&dev_priv->hotplug.hotplug_work);
> +
>  	seq_printf(m, "Threshold: %d\n", hotplug->hpd_storm_threshold);
>  	seq_printf(m, "Detected: %s\n",
>  		   yesno(delayed_work_pending(&hotplug->reenable_work)));
> -- 
> 2.19.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch