Re: [RFC PATCH 3/3] encoder-tpd12s015: keep the ls_oe_gpio on while the phys_addr is valid

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On 12/04/17 16:03, Hans Verkuil wrote:

> I noticed while experimenting with this that tpd_disconnect() in
> drivers/gpu/drm/omapdrm/displays/encoder-tpd12s015.c isn't called when
> I disconnect the HDMI cable. Is that a bug somewhere?
> 
> I would expect that tpd_connect and tpd_disconnect are balanced. The tpd_enable
> and tpd_disable calls are properly balanced and I see the tpd_disable when I
> disconnect the HDMI cable.

The connect/disconnect naming there is legacy... It's not about cable
connect, it's about the initial "connect" of the drivers in the video
pipeline. It's done just once when starting omapdrm.

> The key to keeping CEC up and running, even when there is no HPD is to keep
> the hdmi.vdda_reg regulator enabled. Also the HDMI_IRQ_CORE should always be
> on, otherwise I won't get any CEC interrupts.

At the moment there's no way to enable the pipeline without enabling the
video.

> So if the omap4 CEC support is enabled in the kernel config, then always enable
> this regulator and irq, and otherwise keep the current code.

Well, I have no clue about how CEC is used, but don't we have some
userspace components using it? I presume there's an open() or something
similar that signals that the userspace is interested in CEC. That
should be the trigger to enable the HW required for CEC.

So is some other driver supporting this already? Or is the omap4 the
first platform you're trying this on?

 Tomi

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