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

[Ville Syrjälä]

On Fri, Dec 11, 2015 at 05:05:11AM +0000, Jindal, Sonika wrote:
> How about following instead of two levels of check in the while loop:
> 
> unsigned int retry = 3;
> 
> do {
> 	live_status = intel_digital_port_connected(dev_priv,
> 			hdmi_to_dig_port(intel_hdmi));
> 	if (live_status)
> 		break;
> 	mdelay(10);
> } while (--retry);

How about a straight up for loop instead?

> 
> Regards,
> Sonika
> 
> -----Original Message-----
> From: Intel-gfx [mailto:intel-gfx-bounces at lists.freedesktop.org] On Behalf Of Wang, Gary C
> Sent: Friday, December 11, 2015 7:39 AM
> To: intel-gfx at lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH] drm/i915: Correct max delay for HDMI hotplug live status checking
> 
> The total delay of HDMI hotplug detecting with 30ms should have 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.
> 
> Reviewed-by: Cooper Chiou <cooper.chiou at intel.com>
> Cc: Gavin Hindman <gavin.hindman at intel.com>
> Signed-off-by: Gary Wang <gary.c.wang at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_hdmi.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 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 be7fab9..888401b
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1387,16 +1387,19 @@ 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;
> +	// read hotplug status 4 times at most for 30ms delay (3 retries of 10ms each)
> +	unsigned int retry = 4;
>  
>  	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) {
> +	while (!live_status && retry--) {
>  		live_status = intel_digital_port_connected(dev_priv,
>  				hdmi_to_dig_port(intel_hdmi));
> +		if (live_status || !retry)
> +				break;
>  		mdelay(10);
>  	}
>  
> --
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC