[Intel-gfx] [PATCH v2] drm/i915: Correct max delay for HDMI hotplug live status checking

[Daniel Vetter]

On Tue, Dec 15, 2015 at 12:40:30PM +0800, Gary Wang wrote:
> The total delay of HDMI hotplug detecting with 30ms have already
> been split into a resolution of 3 retries of 10ms each, for the worst
> cases. But it still suffered from only waiting 10ms at most in
> intel_hdmi_detect(). This patch corrects it by reading hotplug status
> with 4 times at most for 30ms delay.
> 
> v2:
> - straight up to loop execution for more clear in code readability
> - mdelay will replace with msleep by Daniel's new patch
> 
> 	drm/i915: mdelay(10) considered harmful
> 
> - suggest to re-evaluate try times for being compatible to old HDMI monitor
> 
> Reviewed-by: Cooper Chiou <cooper.chiou at intel.com>
> Tested-by: Gary Wang <gary.c.wang at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Daniel Vetter <daniel at ffwll.ch>
> Cc: Gavin Hindman <gavin.hindman at intel.com>
> Cc: Sonika Jindal <sonika.jindal at intel.com>
> Cc: Shashank Sharma <shashank.sharma at intel.com>
> Signed-off-by: Gary Wang <gary.c.wang at intel.com>

Queued for -next (including cc: fixes), thanks for the patch.
-Daniel
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
>  mode change 100644 => 100755 drivers/gpu/drm/i915/intel_hdmi.c
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> old mode 100644
> new mode 100755
> index 6825543..912d6c3
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1387,17 +1387,18 @@ intel_hdmi_detect(struct drm_connector *connector, bool force)
>  	struct intel_hdmi *intel_hdmi = intel_attached_hdmi(connector);
>  	struct drm_i915_private *dev_priv = to_i915(connector->dev);
>  	bool live_status = false;
> -	unsigned int retry = 3;
> +	unsigned int try;
>  
>  	DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n",
>  		      connector->base.id, connector->name);
>  
>  	intel_display_power_get(dev_priv, POWER_DOMAIN_GMBUS);
>  
> -	while (!live_status && --retry) {
> +	for (try = 0; !live_status && try < 4; try++) {
> +		if (try)
> +			mdelay(10);
>  		live_status = intel_digital_port_connected(dev_priv,
>  				hdmi_to_dig_port(intel_hdmi));
> -		mdelay(10);
>  	}
>  
>  	if (!live_status)
> -- 
> 1.9.1
> 

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