[PATCH 2/4] staging: imx-hdmi: correct connector detect and hotplug

Russell King - ARM Linux linux at arm.linux.org.uk
Sun Apr 13 14:58:10 UTC 2014


On Fri, Apr 11, 2014 at 04:13:33PM +0200, Lucas Stach wrote:
> Make sure that we probe for a display on detect regardless
> of previous hotplug events. Don't handle connector
> hotplug state ourselves, but let DRM do the right thing
> for us. This brings our hotplug handling in line with
> what other DRM drivers do.

Why should working setups have to pay the price for faulty setups when we
can adequately detect the hotplug signal on iMX SoCs when it's correctly
wired?

By "price" I mean - if we end up having to poll the connector, we end up
calling the i2c functions, and the i2c functions on iMX use a fixed
timeout of 100ms.  That means the context which runs the
imx_hdmi_connector_detect() function is forced to sleep for 100ms.  If
that's being run as part of a softirq (eg, via a work struct), that's
bad news because that could be any thread in the system.

The "price" should only be paid by those implementations where the hotplug
signal is not correctly wired.

-- 
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.


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