RE: [PATCH v3 05/11] mtd: cfi_cmdset_0002: Split do_write_oneword() to reduce function size

[IKEGAMI Tokunori <ikegami@xxxxxxxxxxxxxxxxxxxx>]

> -----Original Message-----
> From: Boris Brezillon [mailto:boris.brezillon@xxxxxxxxxxx]
> Sent: Monday, November 05, 2018 10:32 PM
> To: IKEGAMI Tokunori
> Cc: boris.brezillon@xxxxxxxxxxxxxxxxxx; Fabio Bettoni; PACKHAM Chris;
> Joakim Tjernlund; linux-mtd@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [PATCH v3 05/11] mtd: cfi_cmdset_0002: Split
> do_write_oneword() to reduce function size
> 
> On Fri, 26 Oct 2018 01:32:13 +0900
> Tokunori Ikegami <ikegami@xxxxxxxxxxxxxxxxxxxx> wrote:
> 
> > Reduce the size of do_write_oneword() by extracting a helper function
> > for the hardware access.
> >
> > Signed-off-by: Tokunori Ikegami <ikegami@xxxxxxxxxxxxxxxxxxxx>
> > Reviewed-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> > Cc: Fabio Bettoni <fbettoni@xxxxxxxxx>
> > Co: Hauke Mehrtens <hauke@xxxxxxxxxx>
> > Co: Koen Vandeputte <koen.vandeputte@xxxxxxxxxxxx>
> > Cc: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
> > Cc: Joakim Tjernlund <Joakim.Tjernlund@xxxxxxxxxxxx>
> > Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> > Cc: linux-mtd@xxxxxxxxxxxxxxxxxxx
> > ---
> > Changes since v2:
> > - Just update the commit message for the comment
> > - Add Reviewed-by tag.
> >
> > Changes since v1:
> > - Add the patch.
> >
> >  drivers/mtd/chips/cfi_cmdset_0002.c | 89
> ++++++++++++++++-------------
> >  1 file changed, 50 insertions(+), 39 deletions(-)
> >
> > diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c
> b/drivers/mtd/chips/cfi_cmdset_0002.c
> > index a3fa2d7b1ba0..ae2d8bd7154e 100644
> > --- a/drivers/mtd/chips/cfi_cmdset_0002.c
> > +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
> > @@ -1547,11 +1547,10 @@ static int cfi_amdstd_lock_user_prot_reg(struct
> mtd_info *mtd, loff_t from,
> >  				   do_otp_lock, 1);
> >  }
> >
> > -static int __xipram do_write_oneword(struct map_info *map, struct flchip
> *chip,
> > -				     unsigned long adr, map_word datum,
> > -				     int mode)
> > +static int __xipram do_write_oneword_once(struct map_info *map, struct
> flchip *chip,
> > +					  unsigned long adr, map_word
> datum,
> > +					  int mode, struct cfi_private
> *cfi)
> >  {
> > -	struct cfi_private *cfi = map->fldrv_priv;
> >  	unsigned long timeo = jiffies + HZ;
> >  	/*
> >  	 * We use a 1ms + 1 jiffies generic timeout for writes (most devices
> > @@ -1564,42 +1563,7 @@ static int __xipram do_write_oneword(struct
> map_info *map, struct flchip *chip,
> >  	 */
> >  	unsigned long uWriteTimeout = (HZ / 1000) + 1;
> >  	int ret = 0;
> > -	map_word oldd;
> > -	int retry_cnt = 0;
> > -
> > -	adr += chip->start;
> > -
> > -	mutex_lock(&chip->mutex);
> > -	ret = get_chip(map, chip, adr, mode);
> > -	if (ret) {
> > -		mutex_unlock(&chip->mutex);
> > -		return ret;
> > -	}
> >
> > -	pr_debug("MTD %s(): WRITE 0x%.8lx(0x%.8lx)\n",
> > -		 __func__, adr, datum.x[0]);
> > -
> > -	if (mode == FL_OTP_WRITE)
> > -		otp_enter(map, chip, adr, map_bankwidth(map));
> > -
> > -	/*
> > -	 * Check for a NOP for the case when the datum to write is already
> > -	 * present - it saves time and works around buggy chips that corrupt
> > -	 * data at other locations when 0xff is written to a location that
> > -	 * already contains 0xff.
> > -	 */
> > -	oldd = map_read(map, adr);
> > -	if (map_word_equal(map, oldd, datum)) {
> > -		pr_debug("MTD %s(): NOP\n",
> > -		       __func__);
> > -		goto op_done;
> > -	}
> > -
> > -	XIP_INVAL_CACHED_RANGE(map, adr, map_bankwidth(map));
> > -	ENABLE_VPP(map);
> > -	xip_disable(map, chip, adr);
> > -
> > - retry:
> >  	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
> cfi->device_type, NULL);
> >  	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi,
> cfi->device_type, NULL);
> >  	cfi_send_gen_cmd(0xA0, cfi->addr_unlock1, chip->start, map, cfi,
> cfi->device_type, NULL);
> > @@ -1642,6 +1606,53 @@ static int __xipram do_write_oneword(struct
> map_info *map, struct flchip *chip,
> >  		UDELAY(map, chip, adr, 1);
> >  	}
> >
> > +	return ret;
> > +}
> > +
> > +static int __xipram do_write_oneword(struct map_info *map, struct flchip
> *chip,
> > +				     unsigned long adr, map_word datum,
> > +				     int mode)
> > +{
> > +	struct cfi_private *cfi = map->fldrv_priv;
> > +	int ret = 0;
> > +	map_word oldd;
> > +	int retry_cnt = 0;
> > +
> > +	adr += chip->start;
> > +
> > +	mutex_lock(&chip->mutex);
> > +	ret = get_chip(map, chip, adr, mode);
> > +	if (ret) {
> > +		mutex_unlock(&chip->mutex);
> > +		return ret;
> > +	}
> > +
> > +	pr_debug("MTD %s(): WRITE 0x%.8lx(0x%.8lx)\n",
> > +		 __func__, adr, datum.x[0]);
> > +
> > +	if (mode == FL_OTP_WRITE)
> > +		otp_enter(map, chip, adr, map_bankwidth(map));
> > +
> > +	/*
> > +	 * Check for a NOP for the case when the datum to write is already
> > +	 * present - it saves time and works around buggy chips that corrupt
> > +	 * data at other locations when 0xff is written to a location that
> > +	 * already contains 0xff.
> > +	 */
> > +	oldd = map_read(map, adr);
> > +	if (map_word_equal(map, oldd, datum)) {
> > +		pr_debug("MTD %s(): NOP\n",
> > +		       __func__);
> > +		goto op_done;
> > +	}
> > +
> > +	XIP_INVAL_CACHED_RANGE(map, adr, map_bankwidth(map));
> > +	ENABLE_VPP(map);
> > +	xip_disable(map, chip, adr);
> > +
> > + retry:
> > +	ret = do_write_oneword_once(map, chip, adr, datum, mode, cfi);
> > +
> >  	/* Did we succeed? */
> 
> We usually place the ret code check just after the call to the function
> returning this ret code:
> 
> 	ret = do_write_oneword_once(map, chip, adr, datum, mode, cfi);
> 	if (ret) {
> 		...
> 	}
> 
> And I don't think we need the "Did we succeed?" comment, since it's
> pretty obvious what this check does.

I see so I will do fix as this.

> 
> One extra thing you could do to make this piece of code more readable
> is use a for loop for the retry logic:
> 
> 	for (retry_count = 0; retry_count < MAX_RETRIES; retry_count++)
> 	{
> 		ret = do_write_oneword_once(map, chip, adr, datum,
> 					    mode, cfi);
> 		if (!ret)
> 			break;
> 
> 		/* reset on all failures. */
> 		map_write(map, CMD(0xF0), chip->start);
>                 /* FIXME - should have reset delay before continuing */
> 	}

This is changed by the patch 08/11 as so.
Do you mean that the patches should be combined to a patch?

Regards,
Ikegami

> 
> >  	if (ret) {
> >  		/* reset on all failures. */


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