linux-kernel - Re: [PATCH v1 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC

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Date:   Thu, 16 Apr 2020 12:26:19 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     "Ramuthevar, Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@...ux.intel.com>
Cc:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        anders.roxell@...aro.org, andriy.shevchenko@...el.com,
        arnd@...db.de, brendanhiggins@...gle.com, cheol.yong.kim@...el.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mtd@...ts.infradead.org, masonccyang@...c.com.tw,
        miquel.raynal@...tlin.com, piotrs@...ence.com,
        qi-ming.wu@...el.com, richard@....at, robh+dt@...nel.org,
        tglx@...utronix.de, vigneshr@...com
Subject: Re: [PATCH v1 2/2] mtd: rawnand: Add NAND controller support on
 Intel LGM SoC

On Thu, 16 Apr 2020 17:45:49 +0800
"Ramuthevar, Vadivel MuruganX"
<vadivel.muruganx.ramuthevar@...ux.intel.com> wrote:

> >>>> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@...ux.intel.com>
> >>>>
> >>>> This patch adds the new IP of Nand Flash Controller(NFC) support
> >>>> on Intel's Lightning Mountain(LGM) SoC.
> >>>>
> >>>> DMA is used for burst data transfer operation, also DMA HW supports
> >>>> aligned 32bit memory address and aligned data access by default.
> >>>> DMA burst of 8 supported. Data register used to support the read/write
> >>>> operation from/to device.  
> >>> I am wondering how this new hardware is different from the Lantiq NAND
> >>> controller IP - for which there is already a driver in mainline (it's
> >>> in drivers/mtd/nand/raw/xway_nand.c).
> >>> The CON and WAIT registers look suspiciously similar.
> >>>
> >>> As far as I understand the "old" SoCs (VRX200 and earlier) don't have
> >>> a built-in ECC engine. This seems to have changed with ARX300 though
> >>> (again, AFAIK).
> >>>
> >>> A bit of lineage on these SoCs (initially these were developed by
> >>> Infineon. Lantiq then started as an Infineon spin-off in 2009 and
> >>> was then acquired by Intel in 2015):
> >>> - Danube
> >>> - ARX100 from 2008/2009
> >>> - VRX200 from 2009/2010
> >>> - ARX300 from 2014
> >>> - GRX350 from 2015/2016
> >>> - GRX550 from 2017
> >>> - and now finally: LGM from 2020 (est.)
> >>>
> >>> The existing xway_nand driver supports the Danube, ARX100 and VRX200
> >>> SoCs.  
> >> Lantiq upstreamed a driver for an older version of this IP core 8 years
> >> ago, see here:
> >> https://elixir.bootlin.com/linux/v5.5.6/source/drivers/mtd/nand/raw/xway_nand.c
> >> It does not support DMA and ECC.  
> > Then let's just extend this driver to support the new features. Plus,  
> We do not have the platform to test also it's very old legacy driver .

Well, if it's similar enough, we want to have one driver.

> > we'll be happy to have one more of the existing driver converted to  
> > ->exec_op() ;-).  
> 
> I have completely adapted to ->exec_op() hook up to replace the legacy 
> call-back.

I suspect porting what you've done to the xway driver shouldn't be too
complicated.