i.MX ProcessorsのトピックRe: userspace hdmi detection

userspace hdmi detection

allanmatthew — Mon, 31 Aug 2015 00:48:56 GMT

How would it be possible for a userspace application to detect the status of the HDMI connection on the i.mx6? For instance, when the HDMI is connected to a monitor, I'd like to start a process.

Re: userspace hdmi detection

art — Mon, 31 Aug 2015 14:13:45 GMT

Please refer to the Chapter 16 of the i.MX6 Series Linux BSP Reference Manual document, available as the part of the L3.14.28_1.0.0_LINUX_DOCS bundle on the Freescale web site (check the "Supporting Information" section):

http://www.freescale.com/products/arm-processors/i.mx-applications-processors-based-on-arm-cores/i.mx-6-processors/i.mx6qp/sabre-platform-for-smart-devices-reference-design-based-on-the-i.mx-6-series:RDIMX6SABREPLAT?fpsp=1&tab=Documentation_Tab

In particular, it describes the hotplug detection capability of the L3.14.28 BSP HDMI driver.

Have a great day,
Artur

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Re: userspace hdmi detection

allanmatthew — Mon, 31 Aug 2015 16:37:11 GMT

Hi Artur-

Thanks for this. I looked through the documentation, but theres nothing obvious to me about the HPD status getting exposed to userspace. It looks like it only generates an interrupt that the HDMI driver handles.

Is there a way to view the HPD status in userspace, like in sysfs or /proc? Or do I need to look at a memory mapped register?

-Allan

Re: userspace hdmi detection

Sasamy — Mon, 31 Aug 2015 18:50:39 GMT

Hi Allan,

cable connection status can be seen in sysfs

linux-2.6-imx.git - Freescale i.MX Linux Tree

# find /sys -name cable_state

/sys/devices/soc0/soc.0/20e0000.hdmi_video/cable_state

# cat /sys/devices/soc0/soc.0/20e0000.hdmi_video/cable_state

plugin

# cat /sys/devices/soc0/soc.0/20e0000.hdmi_video/cable_state

plugout

Alexander