linux-kernel - Re: [PATCH v3 1/3] mtd: rawnand: denali_dt: add more clocks based on IP datasheet

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Date:   Mon, 18 Jun 2018 14:18:00 +0200
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Boris Brezillon <boris.brezillon@...tlin.com>
Cc:     Richard Weinberger <richard@....at>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        linux-mtd@...ts.infradead.org, Rob Herring <robh+dt@...nel.org>,
        linux-kbuild@...r.kernel.org,
        "linux-stable #4 . 14+" <stable@...r.kernel.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Marek Vasut <marek.vasut@...il.com>,
        Brian Norris <computersforpeace@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v3 1/3] mtd: rawnand: denali_dt: add more clocks based
 on IP datasheet

Hi Boris,

On Mon, 18 Jun 2018 09:46:36 +0200, Boris Brezillon
<boris.brezillon@...tlin.com> wrote:

> On Mon, 18 Jun 2018 09:09:02 +0200
> Richard Weinberger <richard@....at> wrote:
> 
> > Am Freitag, 15. Juni 2018, 03:18:50 CEST schrieb Masahiro Yamada:  
> > > According to the Denali User's Guide, this IP needs three clocks:
> > > 
> > >  - clk: controller core clock
> > > 
> > >  - clk_x: bus interface clock
> > > 
> > >  - ecc_clk: clock at which ECC circuitry is run
> > > 
> > > Currently, denali_dt.c requires a single anonymous clock and its
> > > frequency.  However, the driver needs to get the frequency of "clk_x"
> > > not "clk".  This is confusing because people tend to assume the
> > > anonymous clock means the core clock.  In fact, I got a report of
> > > SOCFPGA breakage because the timing parameters are calculated based
> > > on a wrong frequency.
> > > 
> > > Instead of the cheesy implementation, the clocks in the real hardware
> > > should be represented in the driver and the DT-binding.
> > > 
> > > However, adding new clocks would break the existing platforms.  For the
> > > backward compatibility, the driver still accepts a single clock just as
> > > before.  If clk_x is missing, clk_x_rate is set to a hardcoded value.
> > > This is fine for existing DT of Socionext UniPhier, and also fixes the
> > > issue of Altera (Intel) SOCFPGA because both platforms use 200 MHz for
> > > the bus interface clock.
> > > 
> > > Fixes: 1bb88666775e ("mtd: nand: denali: handle timing parameters by setup_data_interface()")
> > > Cc: linux-stable <stable@...r.kernel.org> #4.14+
> > > Reported-by: Richard Weinberger <richard@....at>
> > > Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>    
> > 
> > Reviewed-by: Richard Weinberger <richard@....at>  
> 
> Maybe a
> 
> Tested-by: Richard Weinberger <richard@....at>
> 
> ?
> 
> > Reported-by: Philipp Rosenberger <p.rosenberger@...utronix.de>  
> 
> Should I replace your Reported-by by this one or simply add it?
> 
> Miquel, I'll take this patch in mtd/fixes, and let you take the 2
> others in nand/next. That means you'll have to back merge v4.18-rc2
> into the nand/next tree, or base your tree on v4.18-rc2 instead of
> v4.18-rc1.

Sure.

Miquèl