Re: [PATCH 0/5] mtd: rawnand: qcom: Add support for QSPI nand

[mdalam]

On 2020-10-28 15:18, Miquel Raynal wrote:
> Hello,
>
> Md Sadre Alam <mdalam@xxxxxxxxxxxxxx> wrote on Sat, 10 Oct 2020
> 11:01:37 +0530:
>
> > QPIC 2.0 supports Serial NAND support in addition to all features and
> > commands in QPIC 1.0 for parallel NAND. Parallel and Serial NAND 
> > cannot
> > operate simultaneously. QSPI nand devices will connect to QPIC 
> > IO_MACRO
> > block of QPIC controller. There is a separate IO_MACRO clock for 
> > IO_MACRO
> > block. Default IO_MACRO block divide the input clock by 4. so if 
> > IO_MACRO
> > input clock is 320MHz then on bus it will be 80MHz, so QSPI nand 
> > device
> > should also support this frequency.
> >
> > QPIC provides 4 data pins to QSPI nand. In standard SPI mode (x1 mode) 
> > data
> > transfer will occur on only 2 pins one pin for Serial data in and one 
> > for
> > serial data out. In QUAD SPI mode (x4 mode) data transfer will occur 
> > at all
> > the four data lines. QPIC controller supports command for x1 mode and 
> > x4 mode.
> >
> > Md Sadre Alam (5):
> >   dt-bindings: qcom_nandc: IPQ5018 QPIC NAND documentation
> >   mtd: rawnand: qcom: Add initial support for qspi nand
> >   mtd: rawnand: qcom: Read QPIC version
> >   mtd: rawnand: qcom: Enable support for erase,read & write for serial
> >     nand.
> >   mtd: rawnand: qcom: Add support for serial training.
> >
> >  .../devicetree/bindings/mtd/qcom_nandc.txt         |   3 +
> >  drivers/mtd/nand/raw/nand_ids.c                    |  13 +
> >  drivers/mtd/nand/raw/qcom_nandc.c                  | 502 
> > ++++++++++++++++++++-
> >  3 files changed, 494 insertions(+), 24 deletions(-)
>
> I'm sorry but this series clearly breaks the current layering. I cannot
> authorize SPI-NAND code to fall into the raw NAND subsystem.

I am agree with you, we should not add SPI-NAND changes inside
raw NAND subsystem.

> As both typologies cannot be used at the same time, I guess you should
> have another driver handling this feature under the spi/ subsystem +
> a few declarations in the SPI-NAND devices list.

Initially I was started writing separate driver under SPI-NAND subsystem 
then I
realized that more than 85% of raw/qcom_nand.c code getting duplicated.

That's why I have added this SPI-NAND change in raw/qcom_nand.c since
more than 85% of code will be reused.

If I will add this change inside SPI-NAND subsystem then much of
raw/qcom_nand.c code will get duplicated. Would it be ok ?

> Thanks,
> Miquèl