linux-kernel - Re: [PATCH] arm: dts: socfpga: denali needs nand_x

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Date:   Mon, 25 Jun 2018 16:55:06 +0200
From:   Boris Brezillon <boris.brezillon@...tlin.com>
To:     Dinh Nguyen <dinguyen@...nel.org>
Cc:     Richard Weinberger <richard@....at>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mtd <linux-mtd@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Marek Vašut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH] arm: dts: socfpga: denali needs nand_x_clk too

On Mon, 25 Jun 2018 09:50:18 -0500
Dinh Nguyen <dinguyen@...nel.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@....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@....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.
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/dinguyen/linux.git/commit/?h=socfpga_for_next_v4.19_fixes_v1&id=1709ab58eb79b19bceb2287d111bf1bd2df1cf6d

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