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Subject: Re: [PATCH] ARM: dts: da850-evm: add clock properties to the nand
 node
From:   David Lechner <david@lechnology.com>
To:     Sekhar Nori <nsekhar@ti.com>,
        Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc:     Bartosz Golaszewski <brgl@bgdev.pl>,
        Kevin Hilman <khilman@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        arm-soc <linux-arm-kernel@lists.infradead.org>,
        linux-devicetree <devicetree@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
References: <20180205155222.22189-1-brgl@bgdev.pl>
 <3f171f6a-bcea-65ec-d56d-f6ae24660f34@ti.com>
 <CAMpxmJUDbwkcJt_kx9GX+qY10xiGAp-j3+kXM-q3WP1VGwr0UQ@mail.gmail.com>
 <54dbdb98-e0e4-c8c9-fec4-2f050745d9be@ti.com>
 <794024f3-f87a-58ed-2722-a4a2d09df3ce@lechnology.com>
Message-ID: <4aa2ab13-7890-6904-86b3-e2dbcb6d6daa@lechnology.com>
Date:   Tue, 6 Feb 2018 12:25:26 -0600
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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@ti.com>:
>>>> On Monday 05 February 2018 09:22 PM, Bartosz Golaszewski wrote:
>>>>> From: Bartosz Golaszewski <bgolaszewski@baylibre.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@baylibre.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@b0000000 {
---