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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Tue, 26 Jun 2018 11:38:21 +0900
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Subject: Re: [PATCH] arm: dts: socfpga: denali needs nand_x_clk too
To:     Boris Brezillon <boris.brezillon@bootlin.com>
Cc:     Dinh Nguyen <dinguyen@kernel.org>,
        Richard Weinberger <richard@nod.at>,
        DTML <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mtd <linux-mtd@lists.infradead.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        =?UTF-8?B?TWFyZWsgVmHFoXV0?= <marek.vasut@gmail.com>,
        Brian Norris <computersforpeace@gmail.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Miquel Raynal <miquel.raynal@bootlin.com>
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2018-06-25 23:55 GMT+09:00 Boris Brezillon <boris.brezillon@bootlin.com>:
> On Mon, 25 Jun 2018 09:50:18 -0500
> Dinh Nguyen <dinguyen@kernel.org> wrote:
>
>> On 06/22/2018 10:58 AM, Richard Weinberger wrote:
>> > Masahiro,
>> >
>> > Am Freitag, 22. Juni 2018, 16:37:21 CEST schrieb Masahiro Yamada:
>> >> Hi Richard,
>> >>
>> >>
>> >> 2018-06-19 21:07 GMT+09:00 Richard Weinberger <richard@nod.at>:
>> >>> The denali NAND flash controller needs at least two clocks to operate,
>> >>> nand_clk and nand_x_clk.
>> >>> Since 1bb88666775e ("mtd: nand: denali: handle timing parameters by
>> >>> setup_data_interface()") nand_x_clk is used to derive timing settings.
>> >>>
>> >>> Signed-off-by: Richard Weinberger <richard@nod.at>
>> >>> ---
>> >>> Strictly speaking denali needs a ecc_clk too, but AFAIK such a clock
>> >>> is not present on this SoC.
>> >>> But my SoCFPGA knowledge is very limited.
>> >>>
>> >>> Thanks,
>> >>> //richard
>> >>> ---
>> >>>  arch/arm/boot/dts/socfpga.dtsi | 3 ++-
>> >>>  1 file changed, 2 insertions(+), 1 deletion(-)
>> >>>
>> >>> diff --git a/arch/arm/boot/dts/socfpga.dtsi b/arch/arm/boot/dts/socfpga.dtsi
>> >>> index 486d4e7433ed..562f7b375bbd 100644
>> >>> --- a/arch/arm/boot/dts/socfpga.dtsi
>> >>> +++ b/arch/arm/boot/dts/socfpga.dtsi
>> >>> @@ -754,7 +754,8 @@
>> >>>                         reg-names = "nand_data", "denali_reg";
>> >>>                         interrupts = <0x0 0x90 0x4>;
>> >>>                         dma-mask = <0xffffffff>;
>> >>> -                       clocks = <&nand_clk>;
>> >>> +                       clocks = <&nand_clk>, <&nand_x_clk>;
>> >>> +                       clock-names = "nand", "nand_x";
>> >>
>> >>
>> >> IMHO, this should be
>> >>
>> >>                           clocks = <&nand_clk>, <&nand_x_clk>, <&nand_x_clk>;
>> >>                           clock-names = "nand", "nand_x", "ecc";
>>
>> No, it should be just the nand_x and ecc.
>>
>> There's already a patch to use the nand_x_clk and not the nand_clk.


Different people try to fix the problem in different ways.

I think it is due to miscommunication across sub-systems.


>>
>> https://git.kernel.org/pub/scm/linux/kernel/git/dinguyen/linux.git/commit/?h=socfpga_for_next_v4.19_fixes_v1&id=1709ab58eb79b19bceb2287d111bf1bd2df1cf6d


This does not break your board.
However, it is not helpful any more.

I already fix the Denali driver
to use the hard-coded clock frequency
if the old binding is used.


BTW, Marek issued Reviewed-by to this patch.


> Hm, are you sure this is accurate? I might be wrong but I find it weird
> that the denali NAND controller IP has been adapted by Xilinx to only

Xilinx?

Do you mean Altera (Intel)?


> take one clk. Isn't that the same clk is feeding all clk inputs of the
> denali block?


-- 
Best Regards
Masahiro Yamada