Re: drm bridge control from another driver

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On 13.02.2019 15:31, Vinay Simha B N wrote:
>
>
> On Wed, Feb 13, 2019 at 7:44 PM Andrzej Hajda <a.hajda@xxxxxxxxxxx
> <mailto:a.hajda@xxxxxxxxxxx>> wrote:
>
>     On 13.02.2019 14:40, Vinay Simha B N wrote:
>     > Andrzej/Daniel,
>     >
>     > please suggest any input on the scenario for temperature control and
>     > dsi bridge enable/disable.
>     >
>     > On Mon, Feb 11, 2019 at 2:41 PM Vinay Simha B N
>     <simhavcs@xxxxxxxxx <mailto:simhavcs@xxxxxxxxx>
>     > <mailto:simhavcs@xxxxxxxxx <mailto:simhavcs@xxxxxxxxx>>> wrote:
>     >
>     >     dsi2hdmi(adv7511) chip operating temperature range is -10 degC
>     >     to +85 degC. We want to enable/disable the bridge only when
>     >     temperature range is inbetween these range.
>     >
>     >     We have temperature control chip to read the temp, tLow an tHigh
>     >     can be set. whenever interrupt(alert) triggers we want to
>     >     enablel/disable the bridge.
>     >
>     >     Any suggestion what is the better way to handle this scenario?
>     >
>
>     Why do you need to bother about this quite big range at all?
>
> we are looking for -10 deg C, this system will be used in a place
> where temp goes beyond -20 deg C... processor(apq8016/410c) can handle
> upto -30, but dsi2hdmi(adv7533) chip if enabled beyond -10 deg C, life
> of the chip goes down or it cannot operate at all. 
>
>
>     I guess the best would be to set whole platform operating temperature
>     range, and poweroff/sleep/slow down/??? whole system, not just one
>     random chip, which probably is not the most fragile piece, am I right?
>
> right now we are focused only to disable the hdmi chip if temp goes
> beyond -10, since this is only chip in board faces temp issue, other
> components are fine to go upto -30 deg C.
>
>
>     If you really insist on handling it per chip, you can try to
>     investigate
>     following paths:
>
>     1. Just disable the chip, without noticing drm, other drivers, or
>     userspace, and re-enable it if temperature become acceptable, but I am
>     not sure if this will not change behavior of other chips.
>
> dsi2hdmi tied with drm framework, i need to enable/disable the bridge.
> i can disable the regulators enabled for it , but this does not work
> as we want.
>  
>
>     2. Disable the chip and report to the drm subsystem
>     connector_status_disconnected - this will cause drm to stop display
>     pipeline and userspace notification.
>
> any references/driver on how to disable and report to drm susbsystem
> will help to implement.
> connector_status_disconnected i need to call in the interrupt handler
> of tmp102 driver.


Look at the code of adv7511_hpd_work, it evaluates connector status
based on ADV7511_REG_STATUS, so you can put there temperature check
also, and call 'schedule_work(&adv7511->hpd_work)'

if temperature passes valid temp range.

If you want to do it in mainline, please consult it with adv7511
authors/commiters.


Regards

Andrzej


>
> in userspace when i tried manually  below commands, there is no impact
> in the display.
> /sys/class/drm/card0-HDMI-A-1/status
> echo off > status
> echo on > status
>
>
>     Regards
>
>     Andrzej
>
>
>     >
>     >     regards,
>     >     vinaysimha
>     >
>     >     On Mon, Feb 11, 2019 at 2:10 PM Daniel Vetter
>     <daniel@xxxxxxxx <mailto:daniel@xxxxxxxx>
>     >     <mailto:daniel@xxxxxxxx <mailto:daniel@xxxxxxxx>>> wrote:
>     >
>     >         On Mon, Feb 11, 2019 at 09:32:54AM +0100, Andrzej Hajda
>     wrote:
>     >         > On 11.02.2019 07:52, Vinay Simha B N wrote:
>     >         > > hi,
>     >         > >
>     >         > > is it possible to control the drm bridge from another
>     >         driver in irq
>     >         > > handler(enable/disable the bridge)?
>     >         >
>     >         >
>     >         > If you mean 'in irq context' the answer is no, usually
>     >         enable/disable
>     >         > callbacks can sleep, so cannot be called from atomic
>     context.
>     >         >
>     >         >
>     >         > >
>     >         > > is there a way to control the "dpms force off" and "dpms
>     >         force on" in
>     >         > > the interrupt handler?
>     >         >
>     >         >
>     >         > Could you elaborate more on both subjects.
>     >
>     >         Yeah, please explain what you want to use this for. dpms
>     on/off is
>     >         controlled by userspace, the kernel should not change that
>     >         state behind
>     >         usersapce's back. If this is for some manuel refresh
>     display,
>     >         then that's
>     >         a bit a different story ofc, but for that you don't want
>     to do
>     >         a real dpms
>     >         force off/on.
>     >         -Daniel
>     >         >
>     >         >
>     >         > Regards
>     >         >
>     >         > Andrzej
>     >         >
>     >         >
>     >         > >
>     >         > > --
>     >         > > regards,
>     >         > > vinaysimha
>     >         > >
>     >         > > _______________________________________________
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>     <mailto:dri-devel@xxxxxxxxxxxxxxxxxxxxx>
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>     <mailto:dri-devel@xxxxxxxxxxxxxxxxxxxxx>>
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>     >         >
>     >         >
>     >         > _______________________________________________
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>     >
>     >         --
>     >         Daniel Vetter
>     >         Software Engineer, Intel Corporation
>     >         http://blog.ffwll.ch
>     >
>     >
>     >
>     >     --
>     >     regards,
>     >     vinaysimha
>     >
>     >
>     >
>     > --
>     > regards,
>     > vinaysimha
>
>
>
>
> -- 
> regards,
> vinaysimha


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