OMAP: clock DT conversion issues with omap36xx
From: Christoph Fritz
Date: Wed Jan 29 2014 - 06:22:00 EST
On Tue, 2014-01-28 at 18:02 +0100, Christoph Fritz wrote:
> On Tue, 2014-01-28 at 15:40 +0200, Tero Kristo wrote:
> >
> > >> Due to a regression since next-20140122 the following errors are present:
> > >>
> > >> - pin sys_clkout2, which gets configured to 24 Mhz by the fourth patch
> > >> in this set, erroneously outputs only 12 Mhz.
> > >> Just out of curiosity, configuring it to 48 Mhz puts out desired 24 Mhz.
> > >>
> > >> - omap_dss, which gets configured by the third patch in this set, fails
> > >> to do 'dss_set_fck_rate(fck);' in
> > >> drivers/video/omap2/dss/dss.c:dss_setup_default_clock() which leads to:
> > >>
> > >> | omapdss_dss: probe of omapdss_dss failed with error -22
> > >> | omapdss CORE error: Failed to initialize DSS platform driver
> > >> | panel-dpi panel-dpi.0: failed to find video source 'dpi.0
> > >>
> > >> Both regressions seem to have something to do with the clock framework.
> > >> Could this be related to the DT clock conversion patches?
> > >
> >
> > Yea its definitely possible, as the clock DT conversion touches pretty
> > much everything. Have you tried whether this works properly with legacy
> > boot? Personally I don't have access to any omap3 devices that would
> > have display and have no possibility to check this out myself. Anyway,
> > my initial guess is that some clock divider setup might be wrong with
> > omap3, or we are missing some ti,set-rate-parent flag for some clock
> > node which prevents escalating clk_set_rate properly. However, it should
> > be easy to debug this by looking at the clock node in question, and its
> > parent nodes to see if there are any problems.
>
> Currently I only analyzed sys_clkout2 (see attachments for full
> clk_summary files):
>
> clk_summary__next-20140115__works_as_expected:
> dpll4_m2_ck 1 1 96000000
> dpll4_m2x2_ck 1 1 96000000
> omap_192m_alwon_fck 1 1 96000000
> omap_96m_alwon_fck 1 2 96000000
> per_96m_fck 0 6 96000000
> mcbsp4_fck 0 1 96000000
> mcbsp3_fck 0 2 96000000
> mcbsp2_fck 0 2 96000000
> cm_96m_fck 2 3 96000000
> clkout2_src_ck 1 1 96000000
> sys_clkout2 1 1 24000000
>
> For real, on pin sys_clkout2 are correctly 24 Mhz measured.
>
> clk_summary__next-20140124__sysclkout2_dss_fails:
> dpll4_m2_ck 1 1 96000000
> dpll4_m2x2_mul_ck 1 1 192000000
> dpll4_m2x2_ck 1 1 192000000
> omap_192m_alwon_fck 0 0 192000000
> omap_96m_alwon_fck 1 2 192000000
> per_96m_fck 0 6 192000000
> mcbsp4_fck 0 1 192000000
> mcbsp3_fck 0 2 192000000
> mcbsp2_fck 0 2 192000000
> cm_96m_fck 2 3 192000000
> clkout2_src_ck 1 1 192000000
> sys_clkout2 1 1 24000000
>
> For real, on pin sys_clkout2 are only ~12 Mhz measured.
>
> So I added this patch:
>
> Subject: [PATCH] ARM: dts: fix omap3 clock multiplier for dpll4_m2x2_ck
>
> Before DT clock conversion, there was no multiplier for dpll4_m2x2_ck.
> So to be compatible again, set dpll4_m2x2_mul_ck multiplier back to 1.
> ---
> arch/arm/boot/dts/omap3xxx-clocks.dtsi | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm/boot/dts/omap3xxx-clocks.dtsi b/arch/arm/boot/dts/omap3xxx-clocks.dtsi
> index cb04d4b..b594050 100644
> --- a/arch/arm/boot/dts/omap3xxx-clocks.dtsi
> +++ b/arch/arm/boot/dts/omap3xxx-clocks.dtsi
> @@ -212,7 +212,7 @@
> #clock-cells = <0>;
> compatible = "fixed-factor-clock";
> clocks = <&dpll4_m2_ck>;
> - clock-mult = <2>;
> + clock-mult = <1>;
> clock-div = <1>;
> };
>
> And it works again. But due to the fact that sys_clkout2 was at 12 Mhz
> instead of 24, shouldn't it have been at 48 caused by "clock-mult = 2 ?
Any ideas on that?
I reverted the patch above and added:
From: Tero Kristo <t-kristo@xxxxxx>
Date: Wed, 29 Jan 2014 11:03:46 +0200
Subject: [PATCH] ARM: dts: omap36xx: fix omap96m_alwon_fck
OMAP36xx has different hardware implementation for the omap96m_alwon_fck
compared to other OMAP3 variants. Reflect this properly in the dts file.
Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
---
arch/arm/boot/dts/omap36xx-clocks.dtsi | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/arm/boot/dts/omap36xx-clocks.dtsi
b/arch/arm/boot/dts/omap36xx-clocks.dtsi
index 2fcf253..24ddf3f 100644
--- a/arch/arm/boot/dts/omap36xx-clocks.dtsi
+++ b/arch/arm/boot/dts/omap36xx-clocks.dtsi
@@ -88,3 +88,12 @@
<&mcbsp4_ick>, <&uart4_fck>;
};
};
+
+&omap_96m_alwon_fck {
+ compatible = "ti,divider-clock";
+ clocks = <&omap_192m_alwon_fck>;
+ ti,bit-shift = <12>;
+ ti,max-div = <2>;
+ reg = <0x0a40>;
+ ti,index-starts-at-one;
+};
But the output of sys_clkout2 is still wrong.
clk_summary__next-20140124__patch_tero_fix_omap96m_alwon_fck
dpll4_m2_ck 1 1 96000000
dpll4_m2x2_mul_ck 1 1 192000000
dpll4_m2x2_ck 1 1 192000000
omap_192m_alwon_fck 1 1 192000000
omap_96m_alwon_fck 1 2 192000000
per_96m_fck 0 6 192000000
mcbsp4_fck 0 1 192000000
mcbsp3_fck 0 2 192000000
mcbsp2_fck 0 2 192000000
cm_96m_fck 2 3 192000000
clkout2_src_ck 1 1 192000000
sys_clkout2 1 1 24000000
Thanks
-- Christoph
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