[PATCH 1/6] arm: dts: k3-j7200-r5-common: Add msmc clk to a72 node

[Neha Malcom Francis]

Hi Aniket

On 23/10/24 11:42, Aniket Limaye wrote:
> 
> On 17/10/24 16:00, Neha Malcom Francis wrote:
>> Hi Aniket
>>
>> On 17/10/24 11:59, Aniket Limaye wrote:
>>> From: Reid Tonking <reidt at ti.com>
>>>
>>> Define the MSMC clk in the a72 node
>>
>> The usage of MSMC and A72SS interchangeably in this series is confusing. Could 
>> you expand on it in the cover letter why in J7200 this clock is defined as 
>> part of the A72 node as opposed to devices that have MSMC as a separate module 
>> altogether with its own clock (like J721S2 and J784S4)?
> 
> Yeah sure. will elaborate in v2:
> 
> The msmc clock frequency needs to be updated as per selected OPP (in PATCH 4). 
> But we don't have a msmc node for j721e/j7200, unlike those in j721s2/j784s4. So 
> we are defining the msmc clock in the a72_0 node, such that it's frequency can 
> be updated along with core clock frequency when OPP_LOW config is selected.
> 
> I am open to suggestions if this is not the right place for it.
> Thanks for the reviews!

Configuring the MSMC interleaver is only required in devices that have more than 
one DDR controller i.e. J721S2 and J784S4. This is what is being done by the 
MSMC driver present in U-Boot (see drivers/ram/k3-ddrss/k3-ddrss.c). This 
configuration is not needed in this device and is probably why we don't have an 
explicit MSMC node.

I was thinking the patch is okay initially considering this, but now am 
wondering whether this is a hacky way to set a clock and should we introduce the 
MSMC as a node cleanly, after all it is hardware that needs to be described. 
What do you think?

> 
> Regards,
> Aniket
> 
>>>
>>> Signed-off-by: Reid Tonking <reidt at ti.com>
>>> Signed-off-by: Aniket Limaye <a-limaye at ti.com>
>>> ---
>>>   arch/arm/dts/k3-j7200-r5-common-proc-board.dts | 10 +++++-----
>>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/arch/arm/dts/k3-j7200-r5-common-proc-board.dts 
>>> b/arch/arm/dts/k3-j7200-r5-common-proc-board.dts
>>> index f096b102793..759a1e83456 100644
>>> --- a/arch/arm/dts/k3-j7200-r5-common-proc-board.dts
>>> +++ b/arch/arm/dts/k3-j7200-r5-common-proc-board.dts
>>> @@ -23,11 +23,11 @@
>>>                   <&k3_pds 202 TI_SCI_PD_EXCLUSIVE>,
>>>                   <&k3_pds 4 TI_SCI_PD_EXCLUSIVE>;
>>>           resets = <&k3_reset 202 0>;
>>> -        clocks = <&k3_clks 61 1>, <&k3_clks 202 2>;
>>> -        clock-names = "gtc", "core";
>>> -        assigned-clocks = <&k3_clks 202 2>, <&k3_clks 61 1>, <&k3_clks 323 0>;
>>> -        assigned-clock-parents= <0>, <0>, <&k3_clks 323 2>;
>>> -        assigned-clock-rates = <2000000000>, <200000000>;
>>> +        clocks = <&k3_clks 61 1>, <&k3_clks 4 1>, <&k3_clks 202 2> ;
>>> +        clock-names = "gtc", "msmc", "core";
>>> +        assigned-clocks = <&k3_clks 202 2>, <&k3_clks 61 1>, <&k3_clks 4 1>, 
>>> <&k3_clks 323 0>;
>>> +        assigned-clock-parents= <0>, <0>, <0>, <&k3_clks 323 2>;
>>> +        assigned-clock-rates = <2000000000>, <200000000>, <1000000000>;
>>>           ti,sci = <&dmsc>;
>>>           ti,sci-proc-id = <32>;
>>>           ti,sci-host-id = <10>;
>>

-- 
Thanking You
Neha Malcom Francis