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

[Ramuthevar, Vadivel MuruganX]

Hi Boris,

ÂÂÂ Thank you for prompt reply...

On 16/4/2020 5:38 pm, Boris Brezillon wrote:
> On Thu, 16 Apr 2020 17:35:26 +0800
> "Ramuthevar, Vadivel MuruganX"
> <vadivel.muruganx.ramuthevar@xxxxxxxxxxxxxxx> wrote:
>
> > Hi Martin,
> >
> >   ÂÂÂ Thank you so much for review comments and your time...
> >
> > On 16/4/2020 6:05 am, Martin Blumenstingl wrote:
> > > Hi,
> > >
> > > first of all: thank you for working on upstreaming this.
> > > Especially since you are going to use the new exec_op style in v2 as
> > > Boris suggested.
> > >   
> > > > From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@xxxxxxxxxxxxxxx>
> > > >
> > > > 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 .
> 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.

Regards
Vadivel
> > This upstream driver works with the xrx200, I do not know how well it
> > works with other SoCs.
> >
> > Regards
> > Vadivel
> > > Best regards,
> > > Martin