Re: [PATCH v3 07/11] dt-bindings: clock: Add StarFive JH7110 system clock and reset generator

Hal Feng
2023-02-22T13:27:47Z

On Tue, 21 Feb 2023 23:39:32 +0000, Conor Dooley wrote:
> On Tue, Feb 21, 2023 at 02:17:17PM -0800, Stephen Boyd wrote:
>> Quoting Conor Dooley (2023-02-16 10:20:34)
>> > On Thu, Feb 16, 2023 at 10:42:20PM +0800, Hal Feng wrote:
>> > > On Tue, 27 Dec 2022 20:15:20 +0000, Conor Dooley wrote:
>> > > > On Mon, Dec 26, 2022 at 12:26:32AM +0800, Hal Feng wrote:
>> > > Please see the picture of these external clocks in clock tree.
>> > >
>> > > # mount -t debugfs none /mnt
>> > > # cat /mnt/clk/clk_summary
>> > > enable prepare protect duty hardware
>> > > clock count count count rate accuracy phase cycle enable
>> > > -------------------------------------------------------------------------------------------------------
>> > > *mclk_ext* 0 0 0 12288000 0 0 50000 Y
>> > > *tdm_ext* 0 0 0 49152000 0 0 50000 Y
>> > > *i2srx_lrck_ext* 0 0 0 192000 0 0 50000 Y
>> > > *i2srx_bclk_ext* 0 0 0 12288000 0 0 50000 Y
>> > > *i2stx_lrck_ext* 0 0 0 192000 0 0 50000 Y
>> > > *i2stx_bclk_ext* 0 0 0 12288000 0 0 50000 Y
>> > > *gmac1_rgmii_rxin* 0 0 0 125000000 0 0 50000 Y
>> > > gmac1_rx 0 0 0 125000000 0 0 50000 Y
>> > > gmac1_rx_inv 0 0 0 125000000 0 180 50000 Y
>> > > *gmac1_rmii_refin* 0 0 0 50000000 0 0 50000 Y
>> > > gmac1_rmii_rtx 0 0 0 50000000 0 0 50000 Y
>> > > gmac1_tx 0 0 0 50000000 0 0 50000 N
>> > > gmac1_tx_inv 0 0 0 50000000 0 180 50000 Y
>> > > *osc* 4 4 0 24000000 0 0 50000 Y
>> > > apb_func 0 0 0 24000000 0 0 50000 Y
>> > > ...
>> > >
>> > > The clock "gmac1_rgmii_rxin" and the clock "gmac1_rmii_refin" are
>> > > actually used as the parent of other clocks.
>> >
>> > > The "dummy" clocks
>> > > you said are all internal clocks.
>> >
>> > No, what I meant by "dummy" clocks is that if you make clocks "required"
>> > in the binding that are not needed by the hardware for operation a
>> > customer of yours might have to add "dummy" clocks to their devicetree
>> > to pass dtbs_check.
>>
>> They can set the phandle specifier to '<0>' to fill in the required
>> property when there isn't anything there. If this is inside an SoC, it
>> is always connected because silicon can't change after it is made
>> (unless this is an FPGA). Therefore, any and all input clocks should be
>> listed as required.
>
>> If the clk controller has inputs that are
>> pads/balls/pins on the SoC then they can be optional if a valid design
>> can leave those pins not connected.
>
> From the discussion on the dts patches, where the clocks have been put
> (intentionally) into board.dts, I've been under the impression that we
> are in this situation.

For the system (sys) clock controller, we are in this situation.
For the always-on (aon) clock controller, we are not, because some input
clocks are inside the SoC.

> Up to Hal to tell us if the hardware is capable of having those inputs
> left unfilled!

The situation is different for v1.2A and v1.3B boards.

For the v1.2A board,
gmac1 only requires "gmac1_rmii_refin", which support 100MHz
gmac0 only requires "gmac0_rgmii_rxin", which support 1000MHz

For the v1.3B board,
gmac1 only requires "gmac1_rgmii_rxin", which support 1000MHz
gmac0 only requires "gmac0_rgmii_rxin", which support 1000MHz

So we should set the "required" property depending on different
boards.

Best regards,
Hal

>
> FWIW, there's a v4 [1] of this series - but the question has yet to be
> resolved.
>
> Thanks,
> Conor.
>
> 1 - https://lore.kernel.org/all/20230221024645.127922-1-hal.feng@starfivetech.com/