* pwm_bl on i.MX6Q broken on 5.4-RC1+
@ 2019-10-16 19:55 ` Adam Ford
0 siblings, 0 replies; 6+ messages in thread
From: Adam Ford @ 2019-10-16 19:55 UTC (permalink / raw)
To: Uwe Kleine-König, arm-soc, Linux Kernel Mailing List,
linux-pwm, Thierry Reding
I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
through the current master (16 Oct 2019), the backlight does not come
on by default. I can get it come on by manually setting the
brightness, but any video activity seems to blank the screen again
until I change the brightness again.
I bisected the patch to 01ccf903edd6 ("pwm: Let pwm_get_state() return
the last implemented state")
If I revert this patch on 5.4-rc3, the issue goes away.
I was hoping someone might have a suggestion on how to fix it to play
nicely with the iMX6Q PWM or revert if no solution can be found.
thank you,
adam
^ permalink raw reply [flat|nested] 6+ messages in thread* pwm_bl on i.MX6Q broken on 5.4-RC1+
@ 2019-10-16 19:55 ` Adam Ford
0 siblings, 0 replies; 6+ messages in thread
From: Adam Ford @ 2019-10-16 19:55 UTC (permalink / raw)
To: Uwe Kleine-König, arm-soc, Linux Kernel Mailing List,
linux-pwm, Thierry Reding
I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
through the current master (16 Oct 2019), the backlight does not come
on by default. I can get it come on by manually setting the
brightness, but any video activity seems to blank the screen again
until I change the brightness again.
I bisected the patch to 01ccf903edd6 ("pwm: Let pwm_get_state() return
the last implemented state")
If I revert this patch on 5.4-rc3, the issue goes away.
I was hoping someone might have a suggestion on how to fix it to play
nicely with the iMX6Q PWM or revert if no solution can be found.
thank you,
adam
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: pwm_bl on i.MX6Q broken on 5.4-RC1+
2019-10-16 19:55 ` Adam Ford
@ 2019-10-20 18:24 ` Ondřej Jirman
-1 siblings, 0 replies; 6+ messages in thread
From: Ondřej Jirman @ 2019-10-20 18:24 UTC (permalink / raw)
To: Adam Ford
Cc: Uwe Kleine-König, arm-soc, Linux Kernel Mailing List,
linux-pwm, Thierry Reding
On Wed, Oct 16, 2019 at 02:55:54PM -0500, Adam Ford wrote:
> I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
> through the current master (16 Oct 2019), the backlight does not come
> on by default. I can get it come on by manually setting the
> brightness, but any video activity seems to blank the screen again
> until I change the brightness again.
You might want to check PWM driver that's used on your SoC. I had a similar
breakage on Allwinner SoCs, and it was caused by a broken get_state callback.
The problem was there for a long time and it was only exposed by the commit you
bisected to.
regards,
o.
> I bisected the patch to 01ccf903edd6 ("pwm: Let pwm_get_state() return
> the last implemented state")
>
> If I revert this patch on 5.4-rc3, the issue goes away.
>
> I was hoping someone might have a suggestion on how to fix it to play
> nicely with the iMX6Q PWM or revert if no solution can be found.
>
> thank you,
>
> adam
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: pwm_bl on i.MX6Q broken on 5.4-RC1+
@ 2019-10-20 18:24 ` Ondřej Jirman
0 siblings, 0 replies; 6+ messages in thread
From: Ondřej Jirman @ 2019-10-20 18:24 UTC (permalink / raw)
To: Adam Ford
Cc: linux-pwm, Thierry Reding, arm-soc, Uwe Kleine-König,
Linux Kernel Mailing List
On Wed, Oct 16, 2019 at 02:55:54PM -0500, Adam Ford wrote:
> I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
> through the current master (16 Oct 2019), the backlight does not come
> on by default. I can get it come on by manually setting the
> brightness, but any video activity seems to blank the screen again
> until I change the brightness again.
You might want to check PWM driver that's used on your SoC. I had a similar
breakage on Allwinner SoCs, and it was caused by a broken get_state callback.
The problem was there for a long time and it was only exposed by the commit you
bisected to.
regards,
o.
> I bisected the patch to 01ccf903edd6 ("pwm: Let pwm_get_state() return
> the last implemented state")
>
> If I revert this patch on 5.4-rc3, the issue goes away.
>
> I was hoping someone might have a suggestion on how to fix it to play
> nicely with the iMX6Q PWM or revert if no solution can be found.
>
> thank you,
>
> adam
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: pwm_bl on i.MX6Q broken on 5.4-RC1+
2019-10-20 18:24 ` Ondřej Jirman
@ 2019-10-21 10:11 ` Uwe Kleine-König
-1 siblings, 0 replies; 6+ messages in thread
From: Uwe Kleine-König @ 2019-10-21 10:11 UTC (permalink / raw)
To: Adam Ford, arm-soc, Linux Kernel Mailing List, linux-pwm, Thierry Reding
Hello Ondřej,
On Sun, Oct 20, 2019 at 08:24:28PM +0200, Ondřej Jirman wrote:
> On Wed, Oct 16, 2019 at 02:55:54PM -0500, Adam Ford wrote:
> > I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
> > through the current master (16 Oct 2019), the backlight does not come
> > on by default. I can get it come on by manually setting the
> > brightness, but any video activity seems to blank the screen again
> > until I change the brightness again.
>
> You might want to check PWM driver that's used on your SoC. I had a similar
> breakage on Allwinner SoCs, and it was caused by a broken get_state callback.
> The problem was there for a long time and it was only exposed by the commit you
> bisected to.
I added Adam to the recipents of the Thread "backlight: pwm_bl:
configure pwm only once per backlight toggle" here on this list. In this
thread the problem is analysed and it's a bit different than for sun4i.
I assume we don't need to follow up on this report given the discussion
is already ongoing elsewhere.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: pwm_bl on i.MX6Q broken on 5.4-RC1+
@ 2019-10-21 10:11 ` Uwe Kleine-König
0 siblings, 0 replies; 6+ messages in thread
From: Uwe Kleine-König @ 2019-10-21 10:11 UTC (permalink / raw)
To: Adam Ford, arm-soc, Linux Kernel Mailing List, linux-pwm, Thierry Reding
Hello Ondřej,
On Sun, Oct 20, 2019 at 08:24:28PM +0200, Ondřej Jirman wrote:
> On Wed, Oct 16, 2019 at 02:55:54PM -0500, Adam Ford wrote:
> > I have an i.MX6Q with an LCD and PWM controlled backlight. On 5.4-RC1
> > through the current master (16 Oct 2019), the backlight does not come
> > on by default. I can get it come on by manually setting the
> > brightness, but any video activity seems to blank the screen again
> > until I change the brightness again.
>
> You might want to check PWM driver that's used on your SoC. I had a similar
> breakage on Allwinner SoCs, and it was caused by a broken get_state callback.
> The problem was there for a long time and it was only exposed by the commit you
> bisected to.
I added Adam to the recipents of the Thread "backlight: pwm_bl:
configure pwm only once per backlight toggle" here on this list. In this
thread the problem is analysed and it's a bit different than for sun4i.
I assume we don't need to follow up on this report given the discussion
is already ongoing elsewhere.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2019-10-21 10:11 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-10-16 19:55 pwm_bl on i.MX6Q broken on 5.4-RC1+ Adam Ford
2019-10-16 19:55 ` Adam Ford
2019-10-20 18:24 ` Ondřej Jirman
2019-10-20 18:24 ` Ondřej Jirman
2019-10-21 10:11 ` Uwe Kleine-König
2019-10-21 10:11 ` Uwe Kleine-König
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