Re: [PATCH 3/3] OMAPDSS: HDMI: Cache EDID

On 28 June 2012 20:44, Tomi Valkeinen [off-list ref] wrote:

On Thu, 2012-06-28 at 18:43 +0530, Jassi Brar wrote:

quoted

A quick reaction of my guts say, we simply enable 5V/HPD_IRQ during
probe and disable during remove.
HDMI enable/disable via /sysfs/ and HPD (de)assertion, switch only
HDMI_PHY on/off.
The user selecting "Autodetect and Configure" option would then equate
to "(un)loading" of the HDMI driver.
Not to mean a trivial job.

One more thing I realized while thinking about this:

While it could be argued that the power draw from having the tpd12s015
always enabled is very small, I think it could matter. If you consider a
phone with HDMI output, it's likely that the phone is locked 99% of the
time. When the phone is locked, there's no need to keep the HDMI HPD
enabled. So this could add to a considerable amount of power wasted, if
the HPD was always enabled.

At least I can't figure out a reason why one would want the HPD to work
when the phone is locked. Also, I have never used the HDMI output on my
phone, so I'd be glad if it was totally powered off if it gave me more
standby hours =).

Of course, I don't suggest imposing any hard rule here.
All I suggest is make it platform dependent and provide a way from
user-space too to enable/disable HPD.