* [PATCH] ARM: dts: microchip: sam9x60: Fix rtc/rtt clock parent
@ 2024-08-20 13:27 Alexander Dahl
2024-08-21 5:51 ` [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks Alexander Dahl
0 siblings, 1 reply; 7+ messages in thread
From: Alexander Dahl @ 2024-08-20 13:27 UTC (permalink / raw)
To: linux-clk
Cc: Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea,
Tudor Ambarus, Nicolas Ferre, Alexandre Belloni,
Codrin Ciubotariu,
open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS,
open list
The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK),
sourced from the 32.768 kHz crystal oscillator.
(The Monitoring domain slow clock (MD_SLCK) is sourced from an internal
RC oscillator which is most probably not precise enough for real time
clock purposes.)
Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board")
Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt")
Signed-off-by: Alexander Dahl <ada@thorsis.com>
---
arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi
index 291540e5d81e..d077afd5024d 100644
--- a/arch/arm/boot/dts/microchip/sam9x60.dtsi
+++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi
@@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 {
compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt";
reg = <0xfffffe20 0x20>;
interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>;
- clocks = <&clk32k 0>;
+ clocks = <&clk32k 1>;
};
pit: timer@fffffe40 {
@@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 {
compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc";
reg = <0xfffffea8 0x100>;
interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>;
- clocks = <&clk32k 0>;
+ clocks = <&clk32k 1>;
};
watchdog: watchdog@ffffff80 {
base-commit: 47ac09b91befbb6a235ab620c32af719f8208399
--
2.39.2
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-20 13:27 [PATCH] ARM: dts: microchip: sam9x60: Fix rtc/rtt clock parent Alexander Dahl @ 2024-08-21 5:51 ` Alexander Dahl 2024-08-21 23:52 ` Alexandre Belloni 2024-08-24 17:28 ` claudiu beznea 0 siblings, 2 replies; 7+ messages in thread From: Alexander Dahl @ 2024-08-21 5:51 UTC (permalink / raw) To: linux-clk Cc: Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, Alexandre Belloni, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), sourced from the 32.768 kHz crystal oscillator. (The previously used Monitoring domain slow clock (MD_SLCK) is sourced from an internal RC oscillator which is most probably not precise enough for real time clock purposes.) Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") Signed-off-by: Alexander Dahl <ada@thorsis.com> --- Notes: Picked the wrong patch in the first try. This v2 one has a slightly adapted commit message and more context below. This obviously requires a 32.768 kHz crystal oscillator to be present, but the sam9x60.dtsi does contain that, and the clock-controllers reference that, so I assume it's always present. /sys/kernel/debug/clk/clk_summary content excerpt before: slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id md_slck 4 4 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id fffffe20.rtc no_connection_id fffffe10.poweroff no_connection_id fffffe00.reset-controller no_connection_id timer@f8008000 slow_clk deviceless no_connection_id … slow_xtal 0 0 0 32768 0 0 50000 Y deviceless no_connection_id slow_osc 0 0 0 32768 0 0 50000 Y deviceless no_connection_id td_slck 0 0 0 32768 0 0 50000 Y deviceless no_connection_id And after: slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id md_slck 2 2 0 32768 0 0 50000 Y fffffe10.poweroff no_connection_id fffffe00.reset-controller no_connection_id timer@f8008000 slow_clk deviceless no_connection_id … slow_xtal 1 1 0 32768 0 0 50000 Y deviceless no_connection_id slow_osc 1 1 0 32768 0 0 50000 Y deviceless no_connection_id td_slck 2 2 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id fffffe20.rtc no_connection_id deviceless no_connection_id arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi index 291540e5d81e..d077afd5024d 100644 --- a/arch/arm/boot/dts/microchip/sam9x60.dtsi +++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi @@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 { compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt"; reg = <0xfffffe20 0x20>; interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; - clocks = <&clk32k 0>; + clocks = <&clk32k 1>; }; pit: timer@fffffe40 { @@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 { compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc"; reg = <0xfffffea8 0x100>; interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; - clocks = <&clk32k 0>; + clocks = <&clk32k 1>; }; watchdog: watchdog@ffffff80 { base-commit: 47ac09b91befbb6a235ab620c32af719f8208399 -- 2.39.2 ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-21 5:51 ` [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks Alexander Dahl @ 2024-08-21 23:52 ` Alexandre Belloni 2024-08-22 6:53 ` Alexander Dahl 2024-08-24 17:28 ` claudiu beznea 1 sibling, 1 reply; 7+ messages in thread From: Alexandre Belloni @ 2024-08-21 23:52 UTC (permalink / raw) To: Alexander Dahl Cc: linux-clk, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list On 21/08/2024 07:51:36+0200, Alexander Dahl wrote: > The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), > sourced from the 32.768 kHz crystal oscillator. > > (The previously used Monitoring domain slow clock (MD_SLCK) is sourced > from an internal RC oscillator which is most probably not precise enough > for real time clock purposes.) > > Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") > Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") > Signed-off-by: Alexander Dahl <ada@thorsis.com> > --- > > Notes: > Picked the wrong patch in the first try. This v2 one has a slightly > adapted commit message and more context below. > > This obviously requires a 32.768 kHz crystal oscillator to be present, > but the sam9x60.dtsi does contain that, and the clock-controllers > reference that, so I assume it's always present. The crystal is optional so this is going to break the boards that don't have one. I don't really mind but this should probably be part of the commit message. This makes me realise that we always assumed the RC oscillator was running at 32768 while the sam9x60 datasheet refers to it has a 32kHz oscillator. However the RTC only has a 32768 divider... > > /sys/kernel/debug/clk/clk_summary content excerpt before: > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > md_slck 4 4 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > fffffe20.rtc no_connection_id > fffffe10.poweroff no_connection_id > fffffe00.reset-controller no_connection_id > timer@f8008000 slow_clk > deviceless no_connection_id > … > slow_xtal 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > slow_osc 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > td_slck 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > And after: > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > md_slck 2 2 0 32768 0 0 50000 Y fffffe10.poweroff no_connection_id > fffffe00.reset-controller no_connection_id > timer@f8008000 slow_clk > deviceless no_connection_id > … > slow_xtal 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > slow_osc 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > td_slck 2 2 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > fffffe20.rtc no_connection_id > deviceless no_connection_id > > arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi > index 291540e5d81e..d077afd5024d 100644 > --- a/arch/arm/boot/dts/microchip/sam9x60.dtsi > +++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi > @@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 { > compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt"; > reg = <0xfffffe20 0x20>; > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > - clocks = <&clk32k 0>; > + clocks = <&clk32k 1>; > }; > > pit: timer@fffffe40 { > @@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 { > compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc"; > reg = <0xfffffea8 0x100>; > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > - clocks = <&clk32k 0>; > + clocks = <&clk32k 1>; > }; > > watchdog: watchdog@ffffff80 { > > base-commit: 47ac09b91befbb6a235ab620c32af719f8208399 > -- > 2.39.2 > -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-21 23:52 ` Alexandre Belloni @ 2024-08-22 6:53 ` Alexander Dahl 2024-08-22 8:17 ` Alexandre Belloni 0 siblings, 1 reply; 7+ messages in thread From: Alexander Dahl @ 2024-08-22 6:53 UTC (permalink / raw) To: Alexandre Belloni Cc: Alexander Dahl, linux-clk, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list Hello Alexandre, Am Thu, Aug 22, 2024 at 01:52:05AM +0200 schrieb Alexandre Belloni: > On 21/08/2024 07:51:36+0200, Alexander Dahl wrote: > > The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), > > sourced from the 32.768 kHz crystal oscillator. > > > > (The previously used Monitoring domain slow clock (MD_SLCK) is sourced > > from an internal RC oscillator which is most probably not precise enough > > for real time clock purposes.) > > > > Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") > > Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") > > Signed-off-by: Alexander Dahl <ada@thorsis.com> > > --- > > > > Notes: > > Picked the wrong patch in the first try. This v2 one has a slightly > > adapted commit message and more context below. > > > > This obviously requires a 32.768 kHz crystal oscillator to be present, > > but the sam9x60.dtsi does contain that, and the clock-controllers > > reference that, so I assume it's always present. > > The crystal is optional so this is going to break the boards that don't > have one. I don't really mind but this should probably be part of the > commit message. Okay right, according to the datasheet (Figure 27.1 SCKC Block Diagram) you don't need that crystal, you can clear TD_OSCSEL and td_slck runs from the internal rc then. However, td_slck is always present, it either sources from the internal slow rc oscillator or the crystal oscillator. And the datasheet says in section 29.1 (PMC): "The Slow Clock Controller (SCKC) selects the source of TD_SLCK (drives the real-time part (RTT/RTC)). The source of MD_SLCK (drives the rest of the system controller: wake-up logic, watchdog, PMC, etc.) is always the slow RC oscillator." md_slck and td_slck are both registered by the at91 sckc driver, and the td_slck gets two parents in of_sam9x60_sckc_setup() when registered by at91_clk_register_sam9x5_slow(). The parent can be switched by clk_sam9x5_slow_set_parent() from sam9x5_slow_ops then, correctly setting the OSCSEL bit. The whole idea of the patch is giving the rtc/rtt td_slck as a parent as documented in the datasheet. I don't see how this should be affected by the parents of td_slck? Am I missing something? > This makes me realise that we always assumed the RC oscillator was > running at 32768 while the sam9x60 datasheet refers to it has a 32kHz > oscillator. However the RTC only has a 32768 divider... When sourced from the internal rc oscillator, this would mean the output would be incorrect, right? How could one prove this? Greets Alex > > > > > /sys/kernel/debug/clk/clk_summary content excerpt before: > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > md_slck 4 4 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > fffffe20.rtc no_connection_id > > fffffe10.poweroff no_connection_id > > fffffe00.reset-controller no_connection_id > > timer@f8008000 slow_clk > > deviceless no_connection_id > > … > > slow_xtal 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > slow_osc 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > td_slck 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > > And after: > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > md_slck 2 2 0 32768 0 0 50000 Y fffffe10.poweroff no_connection_id > > fffffe00.reset-controller no_connection_id > > timer@f8008000 slow_clk > > deviceless no_connection_id > > … > > slow_xtal 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > slow_osc 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > td_slck 2 2 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > fffffe20.rtc no_connection_id > > deviceless no_connection_id > > > > arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > index 291540e5d81e..d077afd5024d 100644 > > --- a/arch/arm/boot/dts/microchip/sam9x60.dtsi > > +++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > @@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 { > > compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt"; > > reg = <0xfffffe20 0x20>; > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > - clocks = <&clk32k 0>; > > + clocks = <&clk32k 1>; > > }; > > > > pit: timer@fffffe40 { > > @@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 { > > compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc"; > > reg = <0xfffffea8 0x100>; > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > - clocks = <&clk32k 0>; > > + clocks = <&clk32k 1>; > > }; > > > > watchdog: watchdog@ffffff80 { > > > > base-commit: 47ac09b91befbb6a235ab620c32af719f8208399 > > -- > > 2.39.2 > > > > -- > Alexandre Belloni, co-owner and COO, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-22 6:53 ` Alexander Dahl @ 2024-08-22 8:17 ` Alexandre Belloni 2024-08-22 10:25 ` Alexander Dahl 0 siblings, 1 reply; 7+ messages in thread From: Alexandre Belloni @ 2024-08-22 8:17 UTC (permalink / raw) To: linux-clk, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list On 22/08/2024 08:53:59+0200, Alexander Dahl wrote: > Hello Alexandre, > > Am Thu, Aug 22, 2024 at 01:52:05AM +0200 schrieb Alexandre Belloni: > > On 21/08/2024 07:51:36+0200, Alexander Dahl wrote: > > > The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), > > > sourced from the 32.768 kHz crystal oscillator. > > > > > > (The previously used Monitoring domain slow clock (MD_SLCK) is sourced > > > from an internal RC oscillator which is most probably not precise enough > > > for real time clock purposes.) > > > > > > Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") > > > Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") > > > Signed-off-by: Alexander Dahl <ada@thorsis.com> > > > --- > > > > > > Notes: > > > Picked the wrong patch in the first try. This v2 one has a slightly > > > adapted commit message and more context below. > > > > > > This obviously requires a 32.768 kHz crystal oscillator to be present, > > > but the sam9x60.dtsi does contain that, and the clock-controllers > > > reference that, so I assume it's always present. > > > > The crystal is optional so this is going to break the boards that don't > > have one. I don't really mind but this should probably be part of the > > commit message. > > Okay right, according to the datasheet (Figure 27.1 SCKC Block > Diagram) you don't need that crystal, you can clear TD_OSCSEL and > td_slck runs from the internal rc then. However, td_slck is always > present, it either sources from the internal slow rc oscillator or the > crystal oscillator. And the datasheet says in section 29.1 (PMC): > > "The Slow Clock Controller (SCKC) selects the source of TD_SLCK > (drives the real-time part (RTT/RTC)). The source of MD_SLCK > (drives the rest of the system controller: wake-up logic, > watchdog, PMC, etc.) is always the slow RC oscillator." > > md_slck and td_slck are both registered by the at91 sckc driver, and > the td_slck gets two parents in of_sam9x60_sckc_setup() when > registered by at91_clk_register_sam9x5_slow(). The parent can be > switched by clk_sam9x5_slow_set_parent() from sam9x5_slow_ops then, > correctly setting the OSCSEL bit. > > The whole idea of the patch is giving the rtc/rtt td_slck as a parent > as documented in the datasheet. I don't see how this should be > affected by the parents of td_slck? Am I missing something? > You are right, I got confused because you were referring t the 32768 Hz crystal in your commit message and though you aimed at selected the parent of td_slck (and also, I didn't really work on the sam9x60). > > This makes me realise that we always assumed the RC oscillator was > > running at 32768 while the sam9x60 datasheet refers to it has a 32kHz > > oscillator. However the RTC only has a 32768 divider... > > When sourced from the internal rc oscillator, this would mean the > output would be incorrect, right? How could one prove this? I guess you could have a look at how the RTC is drifting when selecting the RC osc as the parent but it will anyway be way less precise than the crystal so i'm not sure how you could get a conclusive result. > > Greets > Alex > > > > > > > > > /sys/kernel/debug/clk/clk_summary content excerpt before: > > > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > > md_slck 4 4 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > > fffffe20.rtc no_connection_id > > > fffffe10.poweroff no_connection_id > > > fffffe00.reset-controller no_connection_id > > > timer@f8008000 slow_clk > > > deviceless no_connection_id > > > … > > > slow_xtal 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > slow_osc 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > td_slck 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > > > > And after: > > > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > > md_slck 2 2 0 32768 0 0 50000 Y fffffe10.poweroff no_connection_id > > > fffffe00.reset-controller no_connection_id > > > timer@f8008000 slow_clk > > > deviceless no_connection_id > > > … > > > slow_xtal 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > > slow_osc 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > > td_slck 2 2 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > > fffffe20.rtc no_connection_id > > > deviceless no_connection_id > > > > > > arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > index 291540e5d81e..d077afd5024d 100644 > > > --- a/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > +++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > @@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 { > > > compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt"; > > > reg = <0xfffffe20 0x20>; > > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > > - clocks = <&clk32k 0>; > > > + clocks = <&clk32k 1>; > > > }; > > > > > > pit: timer@fffffe40 { > > > @@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 { > > > compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc"; > > > reg = <0xfffffea8 0x100>; > > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > > - clocks = <&clk32k 0>; > > > + clocks = <&clk32k 1>; > > > }; > > > > > > watchdog: watchdog@ffffff80 { > > > > > > base-commit: 47ac09b91befbb6a235ab620c32af719f8208399 > > > -- > > > 2.39.2 > > > > > > > -- > > Alexandre Belloni, co-owner and COO, Bootlin > > Embedded Linux and Kernel engineering > > https://bootlin.com -- Alexandre Belloni, co-owner and COO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-22 8:17 ` Alexandre Belloni @ 2024-08-22 10:25 ` Alexander Dahl 0 siblings, 0 replies; 7+ messages in thread From: Alexander Dahl @ 2024-08-22 10:25 UTC (permalink / raw) To: Alexandre Belloni Cc: linux-clk, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Claudiu Beznea, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list Hello Alexandre, Am Thu, Aug 22, 2024 at 10:17:46AM +0200 schrieb Alexandre Belloni: > On 22/08/2024 08:53:59+0200, Alexander Dahl wrote: > > Hello Alexandre, > > > > Am Thu, Aug 22, 2024 at 01:52:05AM +0200 schrieb Alexandre Belloni: > > > On 21/08/2024 07:51:36+0200, Alexander Dahl wrote: > > > > The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), > > > > sourced from the 32.768 kHz crystal oscillator. > > > > > > > > (The previously used Monitoring domain slow clock (MD_SLCK) is sourced > > > > from an internal RC oscillator which is most probably not precise enough > > > > for real time clock purposes.) > > > > > > > > Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") > > > > Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") > > > > Signed-off-by: Alexander Dahl <ada@thorsis.com> > > > > --- > > > > > > > > Notes: > > > > Picked the wrong patch in the first try. This v2 one has a slightly > > > > adapted commit message and more context below. > > > > > > > > This obviously requires a 32.768 kHz crystal oscillator to be present, > > > > but the sam9x60.dtsi does contain that, and the clock-controllers > > > > reference that, so I assume it's always present. > > > > > > The crystal is optional so this is going to break the boards that don't > > > have one. I don't really mind but this should probably be part of the > > > commit message. > > > > Okay right, according to the datasheet (Figure 27.1 SCKC Block > > Diagram) you don't need that crystal, you can clear TD_OSCSEL and > > td_slck runs from the internal rc then. However, td_slck is always > > present, it either sources from the internal slow rc oscillator or the > > crystal oscillator. And the datasheet says in section 29.1 (PMC): > > > > "The Slow Clock Controller (SCKC) selects the source of TD_SLCK > > (drives the real-time part (RTT/RTC)). The source of MD_SLCK > > (drives the rest of the system controller: wake-up logic, > > watchdog, PMC, etc.) is always the slow RC oscillator." > > > > md_slck and td_slck are both registered by the at91 sckc driver, and > > the td_slck gets two parents in of_sam9x60_sckc_setup() when > > registered by at91_clk_register_sam9x5_slow(). The parent can be > > switched by clk_sam9x5_slow_set_parent() from sam9x5_slow_ops then, > > correctly setting the OSCSEL bit. > > > > The whole idea of the patch is giving the rtc/rtt td_slck as a parent > > as documented in the datasheet. I don't see how this should be > > affected by the parents of td_slck? Am I missing something? > > > > You are right, I got confused because you were referring t the 32768 Hz > crystal in your commit message and though you aimed at selected the > parent of td_slck (and also, I didn't really work on the sam9x60). Thanks for confirming. Should I reword the commit message then to make it easier to understand? > > > This makes me realise that we always assumed the RC oscillator was > > > running at 32768 while the sam9x60 datasheet refers to it has a 32kHz > > > oscillator. However the RTC only has a 32768 divider... > > > > When sourced from the internal rc oscillator, this would mean the > > output would be incorrect, right? How could one prove this? > > > I guess you could have a look at how the RTC is drifting when selecting > the RC osc as the parent but it will anyway be way less precise than the > crystal so i'm not sure how you could get a conclusive result. I would have to look deeper into rtc for that. Maybe in a calm minute. ;-) Greets Alex > > > > > Greets > > Alex > > > > > > > > > > > > > /sys/kernel/debug/clk/clk_summary content excerpt before: > > > > > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > > > md_slck 4 4 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > > > fffffe20.rtc no_connection_id > > > > fffffe10.poweroff no_connection_id > > > > fffffe00.reset-controller no_connection_id > > > > timer@f8008000 slow_clk > > > > deviceless no_connection_id > > > > … > > > > slow_xtal 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > > slow_osc 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > > td_slck 0 0 0 32768 0 0 50000 Y deviceless no_connection_id > > > > > > > > And after: > > > > > > > > slow_rc_osc 1 1 0 32768 93750000 0 50000 Y deviceless no_connection_id > > > > md_slck 2 2 0 32768 0 0 50000 Y fffffe10.poweroff no_connection_id > > > > fffffe00.reset-controller no_connection_id > > > > timer@f8008000 slow_clk > > > > deviceless no_connection_id > > > > … > > > > slow_xtal 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > > > slow_osc 1 1 0 32768 0 0 50000 Y deviceless no_connection_id > > > > td_slck 2 2 0 32768 0 0 50000 Y fffffea8.rtc no_connection_id > > > > fffffe20.rtc no_connection_id > > > > deviceless no_connection_id > > > > > > > > arch/arm/boot/dts/microchip/sam9x60.dtsi | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/arch/arm/boot/dts/microchip/sam9x60.dtsi b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > > index 291540e5d81e..d077afd5024d 100644 > > > > --- a/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > > +++ b/arch/arm/boot/dts/microchip/sam9x60.dtsi > > > > @@ -1312,7 +1312,7 @@ rtt: rtc@fffffe20 { > > > > compatible = "microchip,sam9x60-rtt", "atmel,at91sam9260-rtt"; > > > > reg = <0xfffffe20 0x20>; > > > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > > > - clocks = <&clk32k 0>; > > > > + clocks = <&clk32k 1>; > > > > }; > > > > > > > > pit: timer@fffffe40 { > > > > @@ -1338,7 +1338,7 @@ rtc: rtc@fffffea8 { > > > > compatible = "microchip,sam9x60-rtc", "atmel,at91sam9x5-rtc"; > > > > reg = <0xfffffea8 0x100>; > > > > interrupts = <1 IRQ_TYPE_LEVEL_HIGH 7>; > > > > - clocks = <&clk32k 0>; > > > > + clocks = <&clk32k 1>; > > > > }; > > > > > > > > watchdog: watchdog@ffffff80 { > > > > > > > > base-commit: 47ac09b91befbb6a235ab620c32af719f8208399 > > > > -- > > > > 2.39.2 > > > > > > > > > > -- > > > Alexandre Belloni, co-owner and COO, Bootlin > > > Embedded Linux and Kernel engineering > > > https://bootlin.com > > -- > Alexandre Belloni, co-owner and COO, Bootlin > Embedded Linux and Kernel engineering > https://bootlin.com > ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks 2024-08-21 5:51 ` [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks Alexander Dahl 2024-08-21 23:52 ` Alexandre Belloni @ 2024-08-24 17:28 ` claudiu beznea 1 sibling, 0 replies; 7+ messages in thread From: claudiu beznea @ 2024-08-24 17:28 UTC (permalink / raw) To: Alexander Dahl, linux-clk Cc: Rob Herring, Krzysztof Kozlowski, Conor Dooley, Codrin Ciubotariu, Sandeep Sheriker Mallikarjun, Nicolas Ferre, Tudor Ambarus, Alexandre Belloni, open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS, open list On 21.08.2024 08:51, Alexander Dahl wrote: > The RTC and RTT peripherals use the "timing domain slow clock (TD_SLCK), > sourced from the 32.768 kHz crystal oscillator. > > (The previously used Monitoring domain slow clock (MD_SLCK) is sourced > from an internal RC oscillator which is most probably not precise enough > for real time clock purposes.) > > Fixes: 1e5f532c2737 ("ARM: dts: at91: sam9x60: add device tree for soc and board") > Fixes: 5f6b33f46346 ("ARM: dts: sam9x60: add rtt") > Signed-off-by: Alexander Dahl <ada@thorsis.com> Applied to at91-dt, thanks! ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2024-08-24 17:28 UTC | newest] Thread overview: 7+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2024-08-20 13:27 [PATCH] ARM: dts: microchip: sam9x60: Fix rtc/rtt clock parent Alexander Dahl 2024-08-21 5:51 ` [PATCH v2] ARM: dts: microchip: sam9x60: Fix rtc/rtt clocks Alexander Dahl 2024-08-21 23:52 ` Alexandre Belloni 2024-08-22 6:53 ` Alexander Dahl 2024-08-22 8:17 ` Alexandre Belloni 2024-08-22 10:25 ` Alexander Dahl 2024-08-24 17:28 ` claudiu beznea
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