Re: [PATCH 1/7] dt-bindings: rtc: sun6i: Add Allwinner A733 support

["Junhui Liu" <junhui.liu@pigmoral.tech>]

Hi ChenYu,
Thanks for your patient review.

On Sat Mar 28, 2026 at 8:37 PM CST, Chen-Yu Tsai wrote:
> On Wed, Jan 21, 2026 at 7:03 PM Junhui Liu <junhui.liu@pigmoral.tech> wrote:
>>
>> The RTC module in the Allwinner A733 SoC is functionally compatible with
>> the sun6i RTC, but its internal Clock Control Unit (CCU) has significant
>> changes.
>>
>> The A733 supports selecting the oscillator between three frequencies:
>> 19.2MHz, 24MHz, and 26MHz. The RTC CCU relies on hardware to detect
>> which frequency is actually used on the board. By defining all three
>> frequencies as fixed-clocks in the device tree, the driver can identify
>> the hardware-detected frequency and expose it to the rest of the system.
>
> No. The board device tree shall have the exact and correct frequency
> defined in the external crystal device node. The operating system can
> use the hardware-detected frequency to "fix" the in-system representation
> if it is off.

Okay, I will keep only one main external crystal in the device tree.

>
>> Additionally, the A733 RTC CCU provides several new DCXO gate clocks for
>> specific modules, including SerDes, HDMI, and UFS.
>>
>> Signed-off-by: Junhui Liu <junhui.liu@pigmoral.tech>
>> ---
>>  .../bindings/rtc/allwinner,sun6i-a31-rtc.yaml      | 38 ++++++++++++++++++++--
>>  include/dt-bindings/clock/sun60i-a733-rtc.h        | 16 +++++++++
>>  2 files changed, 52 insertions(+), 2 deletions(-)
>>

[...]

>> diff --git a/include/dt-bindings/clock/sun60i-a733-rtc.h b/include/dt-bindings/clock/sun60i-a733-rtc.h
>> new file mode 100644
>> index 000000000000..8a2b5facad73
>> --- /dev/null
>> +++ b/include/dt-bindings/clock/sun60i-a733-rtc.h
>> @@ -0,0 +1,16 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only OR MIT */
>> +
>> +#ifndef _DT_BINDINGS_CLK_SUN60I_A733_RTC_H_
>> +#define _DT_BINDINGS_CLK_SUN60I_A733_RTC_H_
>> +
>> +#define CLK_IOSC               0
>> +#define CLK_OSC32K             1
>> +#define CLK_HOSC               2
>
> The DCXO enable control has been present since at least the H6. We just
> never added it, as we would never disable it anyway.

I will remove it.

>
> If you compare the RTC clock trees of the A733 and A523, the only addition
> besides the new gates seems to be the LOSC auto selection. But even that
> is just an illusion, as the A523 has the same registers for that.
>
> One could say the A733 RTC is almost backward compatible to the A523, if
> not for the two fastboot registers the A523 has at 0x120 and 0x124.
>
> So I ask that you try to integrate the differences into the existing
> driver and bindings. You can tweak and export internal clks if you
> need.

Okay, I will try to integrate the A733 RTC support into the existing
driver and bindings.

But first I would like to ask for your advice on how to correctly
organize the device tree binding header for the clocks? I have two ideas
in mind:

1. Add the common internal clocks (e.g., CLK_RTC_32K) to the existing
sun6i-rtc.h. Then, create a new sun60i-a733-rtc.h which includes
the old sun6i-rtc.h and appends the A733-specific clock gates.

2. Simply append all the new A733-specific clock IDs directly to the
bottom of the existing sun6i-rtc.h, sharing the same header file for all
SoCs utilizing this driver.

>
>> +#define CLK_RTC_32K            3
>
> AFAICT besides being an internal clock, this is also fed to GPIO for
> debounce? We probably need to expose this on the A523 as well.
>

I will do it.

>
> Thanks
> ChenYu
>

-- 
Best regards,
Junhui Liu