linux-kernel - Re: [PATCH] ARM: dts: da850-evm: add clock properties to the nand node

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Message-ID: <CAMRc=Mcf0aEQvieNaZ3cMHJTE23Gf1jUNf0=vuO9-PA=9ObDvQ@mail.gmail.com>
Date:   Tue, 6 Feb 2018 19:45:42 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     David Lechner <david@...hnology.com>
Cc:     Sekhar Nori <nsekhar@...com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Kevin Hilman <khilman@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        linux-devicetree <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ARM: dts: da850-evm: add clock properties to the nand node

2018-02-06 19:25 GMT+01:00 David Lechner <david@...hnology.com>:
> On 02/06/2018 12:16 PM, David Lechner wrote:
>>
>> On 02/06/2018 07:51 AM, Sekhar Nori wrote:
>>>
>>> On Tuesday 06 February 2018 06:38 PM, Bartosz Golaszewski wrote:
>>>>
>>>> 2018-02-06 12:07 GMT+01:00 Sekhar Nori <nsekhar@...com>:
>>>>>
>>>>> On Monday 05 February 2018 09:22 PM, Bartosz Golaszewski wrote:
>>>>>>
>>>>>> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>>>>>
>>>>>> Make nand work with the common clock framework by specifying which
>>>>>> clock should be used and what name to look up.
>>>>>>
>>>>>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>>>>> ---
>>>>>>   arch/arm/boot/dts/da850-evm.dts | 3 +++
>>>>>>   1 file changed, 3 insertions(+)
>>>>>>
>>>>>> diff --git a/arch/arm/boot/dts/da850-evm.dts
>>>>>> b/arch/arm/boot/dts/da850-evm.dts
>>>>>> index a86a8a1816f2..2602ad8e99ee 100644
>>>>>> --- a/arch/arm/boot/dts/da850-evm.dts
>>>>>> +++ b/arch/arm/boot/dts/da850-evm.dts
>>>>>> @@ -296,6 +296,9 @@
>>>>>>                        reg = <0 0x02000000 0x02000000
>>>>>>                               1 0x00000000 0x00008000>;
>>>>>>
>>>>>> +                     clocks = <&psc0 3>;
>>>>>> +                     clock-names = "aemif";
>>>>>
>>>>>
>>>>> Looks like this is being added only to satisfy the devm_clk_get() call
>>>>> in nand_davinci_probe() which I think is superfluous since we also
>>>>> enable the same clock in aemif_probe().
>>>>>
>>>>> Perhaps the better solution is to drip the clk code in
>>>>> drivers/mtd/nand/davinci_nand.c and shift legacy code to start using
>>>>> drivers/memory/aemif.c as well? This way we can also drop
>>>>> arch/arm/mach-davinci/aemif.c
>>>>>
>>>>> Thanks,
>>>>> Sekhar
>>>>
>>>>
>>>> Yes, this sounds good, but I think we should leave it for later as an
>>>> additional improvement, once everything else is in place. I think
>>>> these patches should be applied together with David's series in order
>>>> to not break the support on davinci boards and the aemif work would go
>>>> in later as a follow-up. How about that?
>>>
>>>
>>> No, I dont think we should add temporary hacks to DT to work around
>>> driver issues (I do think its a hack since the clock belongs to aemif
>>> module not NAND flash).
>>>
>>> An easier driver hack might be to not treat devm_clk_get() failure in
>>> davinci_nand.c as catastrophic. It will safely fail in DT case and we
>>> should get the clock in legacy boot case.
>>>
>>> I think we are looking at a driver update dependency anyway.
>>
>>
>> It looks like keystone.dtsi is using the clock-ranges property in the
>> aemif node to pass the clock to child nodes. Could we not do the same
>> in da850.dtsi?
>
>
> Bartosz, please try this instead of your patch.
>
> FYI, this is just following the existing memory-controllers/ti-aemif.txt
> device tree bindings, so not a "hack".
>
> ---
> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
> index 3a1f2ce..ff9d807 100644
> --- a/arch/arm/boot/dts/da850.dtsi
> +++ b/arch/arm/boot/dts/da850.dtsi
> @@ -796,6 +796,8 @@
>                 ranges = <0 0 0x60000000 0x08000000
>                           1 0 0x68000000 0x00008000>;
>                 clocks = <&psc0 3>;
> +               clock-names = "aemif";
> +               clock-ranges;
>                 status = "disabled";
>         };
>         memctrl: memory-controller@...00000 {
> ---

Yes, this works. Sekhar: can we include it in David's series, while
still keeping the plan to move legacy boards to using the aemif
driver?

Best regards,
Bartosz