Re: [PATCH 6/7] mtd: nand: mxc: implement onfi get/set features

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Sep 06, 2016 at 02:05:21PM +0200, Boris Brezillon wrote:
> On Tue,  6 Sep 2016 12:39:14 +0200
> Sascha Hauer <s.hauer@pengutronix.de> wrote:
> 
> > To be able to support different ONFI timing modes we have to implement
> > the onfi_set_features and onfi_get_features. Tested on an i.MX25 SoC.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> >  drivers/mtd/nand/mxc_nand.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 53 insertions(+)
> > 
> > diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
> > index 5173fad..1db8299 100644
> > --- a/drivers/mtd/nand/mxc_nand.c
> > +++ b/drivers/mtd/nand/mxc_nand.c
> > @@ -1239,6 +1239,57 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
> >  	}
> >  }
> >  
> > +static int mxc_nand_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip,
> > +			int addr, uint8_t *subfeature_param)
> > +{
> > +	struct nand_chip *nand_chip = mtd_to_nand(mtd);
> > +	struct mxc_nand_host *host = nand_get_controller_data(nand_chip);
> > +	int i;
> > +
> > +	if (!chip->onfi_version ||
> > +	    !(le16_to_cpu(chip->onfi_params.opt_cmd)
> > +	      & ONFI_OPT_CMD_SET_GET_FEATURES))
> > +		return -EINVAL;
> > +
> > +	host->buf_start = 0;
> > +
> > +	for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
> > +		chip->write_byte(mtd, subfeature_param[i]);
> > +
> > +	memcpy32_toio(host->main_area0, host->data_buf, mtd->writesize);
> > +	host->devtype_data->send_cmd(host, NAND_CMD_SET_FEATURES, false);
> > +	mxc_do_addr_cycle(mtd, addr, -1);
> > +	host->devtype_data->send_page(mtd, NFC_INPUT);
> > +
> > +	return 0;
> > +}
> > +
> > +static int mxc_nand_onfi_get_features(struct mtd_info *mtd, struct nand_chip *chip,
> > +			int addr, uint8_t *subfeature_param)
> > +{
> > +	struct nand_chip *nand_chip = mtd_to_nand(mtd);
> > +	struct mxc_nand_host *host = nand_get_controller_data(nand_chip);
> > +	int i;
> > +
> > +	if (!chip->onfi_version ||
> > +	    !(le16_to_cpu(chip->onfi_params.opt_cmd)
> > +	      & ONFI_OPT_CMD_SET_GET_FEATURES))
> > +		return -EINVAL;
> > +
> > +	*(uint32_t *)host->main_area0 = 0xdeadbeef;

This line should be removed by the way.

> > +
> > +	host->devtype_data->send_cmd(host, NAND_CMD_GET_FEATURES, false);
> > +	mxc_do_addr_cycle(mtd, addr, -1);
> > +	host->devtype_data->send_page(mtd, NFC_OUTPUT);
> > +	memcpy32_fromio(host->data_buf, host->main_area0, 512);
> > +	host->buf_start = 0;
> > +
> > +	for (i = 0; i < ONFI_SUBFEATURE_PARAM_LEN; ++i)
> > +		*subfeature_param++ = chip->read_byte(mtd);
> > +
> > +	return 0;
> > +}
> > +
> >  /*
> >   * The generic flash bbt decriptors overlap with our ecc
> >   * hardware, so define some i.MX specific ones.
> > @@ -1513,6 +1564,8 @@ static int mxcnd_probe(struct platform_device *pdev)
> >  	this->read_word = mxc_nand_read_word;
> >  	this->write_buf = mxc_nand_write_buf;
> >  	this->read_buf = mxc_nand_read_buf;
> > +	this->onfi_set_features = mxc_nand_onfi_set_features;
> > +	this->onfi_get_features = mxc_nand_onfi_get_features;
> 
> Do you really have to re-implement ->onfi_{set,get}_features()?
> How about adding support for this command in your ->cmdfunc()
> implementation and relying on the default ->onfi_{set,get}_features()
> provided by the core?

I probably could. The problem is that the generic
nand_onfi_set_features() first sends the command then afterwards uses
chip->write_byte to actually send the data. This is not how the mxc_nand
controller works. On mxc_nand I first need the data before I can issue
the command.
I could implement it in the ->cmdfunc() like: When NAND_CMD_SET_FEATURES
is issued, track that information. Then I have to count how many times
->write_byte() has been called and when I reach
ONFI_SUBFEATURE_PARAM_LEN I have to send the command. While that would
probably work I was glad that I could avoid that. It's one of the
places where one realizes that the nand core layer is built around the
nand controllers of the late nineties.

Sascha

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