linux-kernel - Re: [PATCH V4] mtd: rawnand: qcom: update last code word register

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Date:   Fri, 12 Feb 2021 01:00:47 +0530
From:   mdalam@...eaurora.org
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        boris.brezillon@...labora.com, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, vigneshr@...com,
        sricharan@...eaurora.org
Subject: Re: [PATCH V4] mtd: rawnand: qcom: update last code word register

On 2021-02-11 19:37, Miquel Raynal wrote:
> Hello,
> 
> Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org> wrote on Wed,
> 10 Feb 2021 14:31:44 +0530:
> 
>> On Fri, Jan 29, 2021 at 03:09:19AM +0530, Md Sadre Alam wrote:
>> > From QPIC version 2.0 onwards new register got added to
>> > read last codeword. This change will add the READ_LOCATION_LAST_CW_n
>> > register.
>> >
>> > For first three code word READ_LOCATION_n register will be
>> > use.For last code word READ_LOCATION_LAST_CW_n register will be
>> > use.
> 
> Sorry for the late notice, I think the patch is fine but if you don't
> mind I would like to propose a small change that should simplify your
> patch a lot, see below.
> 
>> >
>> > Signed-off-by: Md Sadre Alam <mdalam@...eaurora.org>
>> 
>> Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
>> 
>> Thanks,
>> Mani
>> 
>> > ---
>> > [V4]
>> >  * Modified condition for nandc_set_read_loc_last() in qcom_nandc_read_cw_raw().
>> >  * Added one additional argument "last_cw" to the function config_nand_cw_read()
>> >    to handle last code word condition.
>> >  * Changed total number of last code word register "NAND_READ_LOCATION_LAST_CW_0" to 4
>> >    while doing code word configuration.
>> >  drivers/mtd/nand/raw/qcom_nandc.c | 110 +++++++++++++++++++++++++++++---------
>> >  1 file changed, 84 insertions(+), 26 deletions(-)
>> >
>> > diff --git a/drivers/mtd/nand/raw/qcom_nandc.c b/drivers/mtd/nand/raw/qcom_nandc.c
>> > index 667e4bf..9484be8 100644
>> > --- a/drivers/mtd/nand/raw/qcom_nandc.c
>> > +++ b/drivers/mtd/nand/raw/qcom_nandc.c
>> > @@ -48,6 +48,10 @@
>> >  #define	NAND_READ_LOCATION_1		0xf24
>> >  #define	NAND_READ_LOCATION_2		0xf28
>> >  #define	NAND_READ_LOCATION_3		0xf2c
>> > +#define	NAND_READ_LOCATION_LAST_CW_0	0xf40
>> > +#define	NAND_READ_LOCATION_LAST_CW_1	0xf44
>> > +#define	NAND_READ_LOCATION_LAST_CW_2	0xf48
>> > +#define	NAND_READ_LOCATION_LAST_CW_3	0xf4c
>> >
>> >  /* dummy register offsets, used by write_reg_dma */
>> >  #define	NAND_DEV_CMD1_RESTORE		0xdead
>> > @@ -187,6 +191,12 @@ nandc_set_reg(nandc, NAND_READ_LOCATION_##reg,			\
>> >  	      ((size) << READ_LOCATION_SIZE) |			\
>> >  	      ((is_last) << READ_LOCATION_LAST))
>> >
>> > +#define nandc_set_read_loc_last(nandc, reg, offset, size, is_last)	\
>> > +nandc_set_reg(nandc, NAND_READ_LOCATION_LAST_CW_##reg,			\
>> > +	      ((offset) << READ_LOCATION_OFFSET) |		\
>> > +	      ((size) << READ_LOCATION_SIZE) |			\
>> > +	      ((is_last) << READ_LOCATION_LAST))
>> > +
> 
> You could rename the macro nandc_set_read_loc() into
> nandc_set_read_loc_first() or anything else that make sense, then have
> a helper which does:
> 
> nandc_set_read_loc()
> {
> 	if (condition for first)
> 		return nandc_set_read_loc_first();
> 	else
> 		return nandc_set_read_loc_last();
> }
> 

   Yes this is more precise way & simplify the patch a lot.
   But for this i have to change these two macro as a function.

   nandc_set_read_loc() & nandc_set_read_loc_last().

   Since for last code word register we are using Token Pasting 
Operator##.

   So if i am implementing like the below.

   /* helper to configure location register values */
   static void nandc_set_read_loc(struct qcom_nand_controller *nandc, int 
reg,
                   int offset, int size, int is_last, bool last_cw)
   {
           if (last_cw)
                   return nandc_set_read_loc_last(nandc, reg, offset, 
size, is_last);
           else
                   return nandc_set_read_loc_first(nandc, reg, offset, 
size, is_last);
  }

   So here for macro expansion reg should be a value not a variable else 
it will be expended like
   NAND_READ_LOCATION_LAST_CW_reg instead of 
NAND_READ_LOCATION_LAST_CW_0,1,2,3 etc.

  the call for nandc_set_read_loc() as nandc_set_read_loc(nandc, 0, 
read_loc, data_size1, 0, true); ---> for last code word.
  nandc_set_read_loc(nandc, 0, read_loc, data_size1, 0, false); ---> for 
first three code wrod.


  So is this ok for you to convert these two macro into function ?

> And in the rest of your patch you won't have to touch anything else.
> 
> Thanks,
> Miquèl