Re: [RFC 02/12] mtd: nand: force drivers to explicitly send READ/PROG commands

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Fri, 20 Oct 2017 11:29:18 +0200
Stefan Agner <stefan@agner.ch> wrote:

> Hi Miquel,
> 
> Thanks for the work on this, happy to see the new interface is moving
> forward. Some comments below.
> 
> On 2017-10-18 16:36, Miquel Raynal wrote:
> > From: Boris Brezillon <boris.brezillon@free-electrons.com>
> > 
> > The core currently send the READ0 and SEQIN+PAGEPROG commands in
> > nand_do_read/write_ops(). This is inconsistent with  
> > ->read/write_oob[_raw]() hooks behavior which are expected to send  
> > these commands.
> > 
> > There's already a flag (NAND_ECC_CUSTOM_PAGE_ACCESS) to inform the core
> > that a specific controller wants to send the READ/SEQIN+PAGEPROG
> > commands on its own, but it's an opt-in flag, and existing drivers are
> > unlikely to be updated to pass it.
> > 
> > Moreover, some controllers cannot dissociate the READ/PAGEPROG commands
> > from the associated data transfer and ECC engine activation, and
> > developers have to hack things in their ->cmdfunc() implementation to
> > handle such complex cases, or have to accept the perf penalty of sending
> > twice the same command.
> > To address this problem we are planning on adding a new interface which
> > is passed all information about a NAND operation (including the amount
> > of data to transfer) and replacing all calls to ->cmdfunc() to calls to
> > this new ->exec_op() hook. But, in order to do that, we need to have all  
> > ->cmdfunc() calls placed near their associated ->read/write_buf/byte()  
> > calls.
> > 
> > Modify the core and relevant drivers to make NAND_ECC_CUSTOM_PAGE_ACCESS
> > the default case, and remove this flag.
> > 
> > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
> > [miquel.raynal@free-electrons.com: rebased and fixed some conflicts]
> > Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
> > ---
> >  drivers/mtd/nand/atmel/nand-controller.c      |  7 ++-
> >  drivers/mtd/nand/bf5xx_nand.c                 |  6 ++-
> >  drivers/mtd/nand/brcmnand/brcmnand.c          | 13 +++--
> >  drivers/mtd/nand/cafe_nand.c                  |  6 +--
> >  drivers/mtd/nand/denali.c                     | 14 +++++-
> >  drivers/mtd/nand/docg4.c                      | 12 +++--
> >  drivers/mtd/nand/fsl_elbc_nand.c              |  6 +--
> >  drivers/mtd/nand/fsl_ifc_nand.c               |  6 +--
> >  drivers/mtd/nand/gpmi-nand/gpmi-nand.c        | 30 ++++++------
> >  drivers/mtd/nand/hisi504_nand.c               |  6 +--
> >  drivers/mtd/nand/lpc32xx_mlc.c                |  5 +-
> >  drivers/mtd/nand/lpc32xx_slc.c                | 11 +++--
> >  drivers/mtd/nand/mtk_nand.c                   | 10 ++--
> >  drivers/mtd/nand/nand_base.c                  | 68 +++++++++------------------
> >  drivers/mtd/nand/nand_micron.c                |  1 -
> >  drivers/mtd/nand/sh_flctl.c                   |  6 +--
> >  drivers/mtd/nand/sunxi_nand.c                 | 34 +++++++++-----
> >  drivers/mtd/nand/tango_nand.c                 |  1 -
> >  drivers/mtd/nand/vf610_nfc.c                  |  6 +--
> >  drivers/staging/mt29f_spinand/mt29f_spinand.c |  7 ++-
> >  include/linux/mtd/rawnand.h                   | 11 -----
> >  21 files changed, 142 insertions(+), 124 deletions(-)
> >   
> 
> <snip>
> 
> > diff --git a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > index c8ceaecd8065..3f2b903158c1 100644
> > --- a/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > +++ b/drivers/mtd/nand/gpmi-nand/gpmi-nand.c
> > @@ -1043,6 +1043,8 @@ static int gpmi_ecc_read_page(struct mtd_info
> > *mtd, struct nand_chip *chip,
> >  	unsigned int  max_bitflips = 0;
> >  	int           ret;
> >  
> > +	nand_read_page_op(chip, page, 0, NULL, 0);
> > +
> >  	dev_dbg(this->dev, "page number is : %d\n", page);
> >  	ret = read_page_prepare(this, buf, nfc_geo->payload_size,
> >  					this->payload_virt, this->payload_phys,
> > @@ -1220,12 +1222,13 @@ static int gpmi_ecc_read_subpage(struct
> > mtd_info *mtd, struct nand_chip *chip,
> >  	meta = geo->metadata_size;
> >  	if (first) {
> >  		col = meta + (size + ecc_parity_size) * first;
> > -		chip->cmdfunc(mtd, NAND_CMD_RNDOUT, col, -1);  
> 
> Shouldn't we add nand_change_read_column_op here?
> 
> 
> >  
> >  		meta = 0;
> >  		buf = buf + first * size;
> >  	}
> >  
> > +	nand_read_page_op(chip, page, col, NULL, 0);
> > +
> >  	/* Save the old environment */
> >  	r1_old = r1_new = readl(bch_regs + HW_BCH_FLASH0LAYOUT0);
> >  	r2_old = r2_new = readl(bch_regs + HW_BCH_FLASH0LAYOUT1);
> > @@ -1277,6 +1280,9 @@ static int gpmi_ecc_write_page(struct mtd_info
> > *mtd, struct nand_chip *chip,
> >  	int        ret;
> >  
> >  	dev_dbg(this->dev, "ecc write page.\n");
> > +
> > +	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
> > +
> >  	if (this->swap_block_mark) {
> >  		/*
> >  		 * If control arrives here, we're doing block mark swapping.
> > @@ -1338,7 +1344,10 @@ static int gpmi_ecc_write_page(struct mtd_info
> > *mtd, struct nand_chip *chip,
> >  				payload_virt, payload_phys);
> >  	}
> >  
> > -	return 0;
> > +	if (ret)
> > +		return ret;
> > +
> > +	return nand_prog_page_end_op(chip);
> >  }
> >  
> >  /*
> > @@ -1472,8 +1481,8 @@ static int gpmi_ecc_read_page_raw(struct mtd_info *mtd,
> >  	uint8_t *oob = chip->oob_poi;
> >  	int step;
> >  
> > -	chip->read_buf(mtd, tmp_buf,
> > -		       mtd->writesize + mtd->oobsize);
> > +	nand_read_page_op(chip, page, 0, tmp_buf,
> > +			  mtd->writesize + mtd->oobsize);
> >  
> >  	/*
> >  	 * If required, swap the bad block marker and the data stored in the
> > @@ -1617,24 +1626,19 @@ static int gpmi_ecc_write_page_raw(struct mtd_info *mtd,
> >  		tmp_buf[mtd->writesize] = swap;
> >  	}
> >  
> > -	chip->write_buf(mtd, tmp_buf, mtd->writesize + mtd->oobsize);
> > -
> > -	return 0;
> > +	return nand_prog_page_op(chip, page, 0, tmp_buf,
> > +				 mtd->writesize + mtd->oobsize);
> >  }
> >  
> >  static int gpmi_ecc_read_oob_raw(struct mtd_info *mtd, struct nand_chip *chip,
> >  				 int page)
> >  {
> > -	nand_read_page_op(chip, page, 0, NULL, 0);
> > -
> >  	return gpmi_ecc_read_page_raw(mtd, chip, NULL, 1, page);
> >  }
> >  
> >  static int gpmi_ecc_write_oob_raw(struct mtd_info *mtd, struct nand_chip *chip,
> >  				 int page)
> >  {
> > -	nand_prog_page_begin_op(chip, page, 0, NULL, 0);
> > -
> >  	return gpmi_ecc_write_page_raw(mtd, chip, NULL, 1, page);
> >  }
> >  
> > @@ -1806,9 +1810,7 @@ static int mx23_write_transcription_stamp(struct
> > gpmi_nand_data *this)
> >  		/* Write the first page of the current stride. */
> >  		dev_dbg(dev, "Writing an NCB fingerprint in page 0x%x\n", page);
> >  
> > -		nand_prog_page_begin_op(chip, page, 0, NULL, 0);
> > -		chip->ecc.write_page_raw(mtd, chip, buffer, 0, page);
> > -		status = nand_prog_page_end_op(chip);
> > +		status = chip->ecc.write_page_raw(mtd, chip, buffer, 0, page);
> >  		if (status)
> >  			dev_err(dev, "[%s] Write failed.\n", __func__);
> >  	}  
> 
> <snip>
> 
> > diff --git a/drivers/mtd/nand/vf610_nfc.c b/drivers/mtd/nand/vf610_nfc.c
> > index 8037d4b48a05..80d31a58e558 100644
> > --- a/drivers/mtd/nand/vf610_nfc.c
> > +++ b/drivers/mtd/nand/vf610_nfc.c
> > @@ -560,7 +560,7 @@ static int vf610_nfc_read_page(struct mtd_info
> > *mtd, struct nand_chip *chip,
> >  	int eccsize = chip->ecc.size;
> >  	int stat;
> >  
> > -	vf610_nfc_read_buf(mtd, buf, eccsize);
> > +	nand_read_page_op(chip, page, 0, buf, eccsize);
> >  	if (oob_required)
> >  		vf610_nfc_read_buf(mtd, chip->oob_poi, mtd->oobsize);
> >  
> > @@ -580,7 +580,7 @@ static int vf610_nfc_write_page(struct mtd_info
> > *mtd, struct nand_chip *chip,
> >  {
> >  	struct vf610_nfc *nfc = mtd_to_nfc(mtd);
> >  
> > -	vf610_nfc_write_buf(mtd, buf, mtd->writesize);  
> 
> We currently ignore NAND_CMD_SEQIN in ->cmdfunc anyway, so I think this
> change would not even be necessary here.

Well, the thing is, we're trying to keep the logic unchanged. Even if
for your driver ->cmdfunc(NAND_CMD_SEQIN) is a NOP, I'd prefer to be
consistent and still replace this ->write_buf() call by a
nand_prog_page_begin_op() one.

> 
> This is a NAND controller which will benefit from the new interface. I
> plan to convert the driver to the new interface, maybe I manage to do
> that soon so we have a second driver making use of the new interface.

Great!!! Let us know if you need any help.

Regards,

Boris