[Letux-kernel] Status 5.0-rc2 on Pyra

Andreas Kemnade andreas at kemnade.info
Mon Jan 21 22:23:42 CET 2019


On Fri, 18 Jan 2019 12:01:43 -0800
Tony Lindgren <tony at atomide.com> wrote:

> * Tony Lindgren <tony at atomide.com> [190117 14:28]:
> > * H. Nikolaus Schaller <hns at goldelico.com> [190117 11:07]:  
> > > This seems to break dmtimer/pwm mode for timer9 which
> > > we use for driving display backlight while timer8
> > > for keyboard backlight still works.  
> > 
> > Oops sorry about that.
> >   
> > > Is there an upcoming patch not yet merged in 5.0-rc2 or
> > > what makes the difference in 5.0 between timer8 and timer9?  
> > 
> > I need to look. Sounds like there might be some optional clock
> > missing in the dts. I'll take a look.
> >   
> > > PS: the symptom is that we don't even see a /sys/class/backlight
> > > node for the display backlight [2].  
> 
> Adding Tero and linux-omap to Cc.
> 
> Nikolaus, care to try the below patch with also timer9 configured
> in your board specific dts file depending what the timer source
> clock should be:
> 
> &timer9 {
> 	assigned-clocks = <&l4_per_clkctrl OMAP5_TIMER9_CLKCTRL 24>;
> 	assigned-clock-parents = <&sys_clkin>;
> };
> 

diff --git a/arch/arm/boot/dts/pyra-display.dtsi b/arch/arm/boot/dts/pyra-display.dtsi
index b219b2961020..9fc793785b89 100644
--- a/arch/arm/boot/dts/pyra-display.dtsi
+++ b/arch/arm/boot/dts/pyra-display.dtsi
@@ -249,6 +249,11 @@
 /* set to e.g. 8300 if display uses a TPS6116x instead of TPS61040 (which is limited to 500 Hz PWM) */
 #define BACKLIGHT_FREQ_HZ      83
 
+&timer9 {
+       assigned-clocks = <&l4per_clkctrl OMAP5_TIMER9_CLKCTRL 24>;
+       assigned-clock-parents = <&sys_clkin>;
+};
+
 / {
        backlight: backlight {
                compatible = "pwm-backlight";

together with the patch sheds light literally on this issue.

> If that works you might as well configure it for timer8 too
> for future :)
> 
> Earlier we had TIMER9_CLKCTRL bit 0 have TIMER9_CLKCTRL bit 24
> as it's parent. But I think we actually have bit 0 as the module
> clock and bit 24 as the timer functional clock. So bit 24 is not
> a parent of bit 0.
> 
> Tero can you check the above assumption?
> 
> If that's not the case then we need more patching..
> 
> Regards,
> 
> Tony
> 
> 8< ----------------
> diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
> --- a/drivers/clocksource/timer-ti-dm.c
> +++ b/drivers/clocksource/timer-ti-dm.c
> @@ -154,6 +154,10 @@ static int omap_dm_timer_of_set_source(struct omap_dm_timer *timer)
>  	if (IS_ERR(parent))
>  		return -ENODEV;
>  
> +	/* Bail out if both clocks point to fck */
> +	if (clk_is_match(parent, timer->fclk))
> +		return 0;
> +
>  	ret = clk_set_parent(timer->fclk, parent);
>  	if (ret < 0)
>  		pr_err("%s: failed to set parent\n", __func__);
> 
Regards,
Andreas
PS nit: why we have l4_per_clkctrl on omap4 and l4per_clkctrl on omap5?
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