[PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[Andy Shevchenko]

Compiler is not happy about used stack frame:

drivers/mtd/chips/cfi_cmdset_0001.c: In function 'do_write_buffer':
drivers/mtd/chips/cfi_cmdset_0001.c:1887:1: error: the frame size of 1296 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]

Fix this by factoring out do_write_buffer_locked().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/mtd/chips/cfi_cmdset_0001.c | 77 +++++++++++++++++------------
 1 file changed, 45 insertions(+), 32 deletions(-)

diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c
index c10693ba265b..8e497e0268f7 100644
--- a/drivers/mtd/chips/cfi_cmdset_0001.c
+++ b/drivers/mtd/chips/cfi_cmdset_0001.c
@@ -1720,40 +1720,24 @@ static int cfi_intelext_write_words (struct mtd_info *mtd, loff_t to , size_t le
 }
 
 
-static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
-				    unsigned long adr, const struct kvec **pvec,
-				    unsigned long *pvec_seek, int len)
+static int __xipram do_write_buffer_locked(struct map_info *map, struct flchip *chip,
+					   unsigned long cmd_adr, unsigned long adr,
+					   const struct kvec **pvec,
+					   unsigned long *pvec_seek, int len)
 {
 	struct cfi_private *cfi = map->fldrv_priv;
 	map_word status, write_cmd, datum;
-	unsigned long cmd_adr;
-	int ret, wbufsize, word_gap, words;
+	int ret, word_gap, words;
 	const struct kvec *vec;
 	unsigned long vec_seek;
 	unsigned long initial_adr;
 	int initial_len = len;
 
-	wbufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
-	adr += chip->start;
 	initial_adr = adr;
-	cmd_adr = adr & ~(wbufsize-1);
-
-	/* Sharp LH28F640BF chips need the first address for the
-	 * Page Buffer Program command. See Table 5 of
-	 * LH28F320BF, LH28F640BF, LH28F128BF Series (Appendix FUM00701) */
-	if (is_LH28F640BF(cfi))
-		cmd_adr = adr;
 
 	/* Let's determine this according to the interleave only once */
 	write_cmd = (cfi->cfiq->P_ID != P_ID_INTEL_PERFORMANCE) ? CMD(0xe8) : CMD(0xe9);
 
-	mutex_lock(&chip->mutex);
-	ret = get_chip(map, chip, cmd_adr, FL_WRITING);
-	if (ret) {
-		mutex_unlock(&chip->mutex);
-		return ret;
-	}
-
 	XIP_INVAL_CACHED_RANGE(map, initial_adr, initial_len);
 	ENABLE_VPP(map);
 	xip_disable(map, chip, cmd_adr);
@@ -1789,7 +1773,7 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
 		xip_enable(map, chip, cmd_adr);
 		printk(KERN_ERR "%s: Chip not ready for buffer write. Xstatus = %lx, status = %lx\n",
 				map->name, Xstatus.x[0], status.x[0]);
-		goto out;
+		return ret;
 	}
 
 	/* Figure out the number of words to write */
@@ -1853,7 +1837,7 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
 		chip->state = FL_STATUS;
 		xip_enable(map, chip, cmd_adr);
 		printk(KERN_ERR "%s: buffer write error (status timeout)\n", map->name);
-		goto out;
+		return ret;
 	}
 
 	/* check for errors */
@@ -1866,21 +1850,50 @@ static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
 		map_write(map, CMD(0x70), cmd_adr);
 		xip_enable(map, chip, cmd_adr);
 
-		if (chipstatus & 0x02) {
-			ret = -EROFS;
-		} else if (chipstatus & 0x08) {
+		if (chipstatus & 0x02)
+			return -EROFS;
+
+		if (chipstatus & 0x08) {
 			printk(KERN_ERR "%s: buffer write error (bad VPP)\n", map->name);
-			ret = -EIO;
-		} else {
-			printk(KERN_ERR "%s: buffer write error (status 0x%lx)\n", map->name, chipstatus);
-			ret = -EINVAL;
+			return  -EIO;
 		}
 
-		goto out;
+		printk(KERN_ERR "%s: buffer write error (status 0x%lx)\n", map->name, chipstatus);
+		return -EINVAL;
 	}
 
 	xip_enable(map, chip, cmd_adr);
- out:	DISABLE_VPP(map);
+	return 0;
+}
+
+static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
+				    unsigned long adr, const struct kvec **pvec,
+				    unsigned long *pvec_seek, int len)
+{
+	struct cfi_private *cfi = map->fldrv_priv;
+	unsigned long cmd_adr;
+	int ret, wbufsize;
+
+	wbufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
+	adr += chip->start;
+	cmd_adr = adr & ~(wbufsize - 1);
+
+	/* Sharp LH28F640BF chips need the first address for the
+	 * Page Buffer Program command. See Table 5 of
+	 * LH28F320BF, LH28F640BF, LH28F128BF Series (Appendix FUM00701) */
+	if (is_LH28F640BF(cfi))
+		cmd_adr = adr;
+
+	mutex_lock(&chip->mutex);
+	ret = get_chip(map, chip, cmd_adr, FL_WRITING);
+	if (ret) {
+		mutex_unlock(&chip->mutex);
+		return ret;
+	}
+
+	ret = do_write_buffer_locked(map, chip, cmd_adr, adr, pvec, pvec_seek, len);
+
+	DISABLE_VPP(map);
 	put_chip(map, chip, cmd_adr);
 	mutex_unlock(&chip->mutex);
 	return ret;
-- 
2.50.1

Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[Andy Shevchenko]

On Sat, Jan 24, 2026 at 01:52:03AM +0100, Andy Shevchenko wrote:
> Compiler is not happy about used stack frame:
> 
> drivers/mtd/chips/cfi_cmdset_0001.c: In function 'do_write_buffer':
> drivers/mtd/chips/cfi_cmdset_0001.c:1887:1: error: the frame size of 1296 bytes is larger than 1280 bytes [-Werror=frame-larger-than=]
> 
> Fix this by factoring out do_write_buffer_locked().

...

>  	XIP_INVAL_CACHED_RANGE(map, initial_adr, initial_len);
>  	ENABLE_VPP(map);

It seems more logical to leave these two in the original call.

...

> +static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
> +				    unsigned long adr, const struct kvec **pvec,
> +				    unsigned long *pvec_seek, int len)
> +{
> +	struct cfi_private *cfi = map->fldrv_priv;
> +	unsigned long cmd_adr;
> +	int ret, wbufsize;
> +
> +	wbufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
> +	adr += chip->start;
> +	cmd_adr = adr & ~(wbufsize - 1);
> +
> +	/* Sharp LH28F640BF chips need the first address for the
> +	 * Page Buffer Program command. See Table 5 of
> +	 * LH28F320BF, LH28F640BF, LH28F128BF Series (Appendix FUM00701) */
> +	if (is_LH28F640BF(cfi))
> +		cmd_adr = adr;
> +
> +	mutex_lock(&chip->mutex);
> +	ret = get_chip(map, chip, cmd_adr, FL_WRITING);
> +	if (ret) {
> +		mutex_unlock(&chip->mutex);
> +		return ret;
> +	}
> +
> +	ret = do_write_buffer_locked(map, chip, cmd_adr, adr, pvec, pvec_seek, len);

> +	DISABLE_VPP(map);

Otherwise this will seem dangling here.

>  	put_chip(map, chip, cmd_adr);
>  	mutex_unlock(&chip->mutex);
>  	return ret;

...

Another approach is to leave goto as is in the _locked() and move DISABLE_VPP()
there.

Tell me what do you prefer?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[Miquel Raynal]

Hi Andy,

>> Fix this by factoring out do_write_buffer_locked().
>
> ...
>
>>  	XIP_INVAL_CACHED_RANGE(map, initial_adr, initial_len);
>>  	ENABLE_VPP(map);
>
> It seems more logical to leave these two in the original call.
>
> ...

[...]

>> +	DISABLE_VPP(map);
>
> Otherwise this will seem dangling here.
>
>>  	put_chip(map, chip, cmd_adr);
>>  	mutex_unlock(&chip->mutex);
>>  	return ret;
>
> ...
>
> Another approach is to leave goto as is in the _locked() and move DISABLE_VPP()
> there.
>
> Tell me what do you prefer?

While I also find more logical to keep the ENABLE_VPP/DISABLE_VPP
together, I do not mind to see them in one side or the other. I would by
default let them in the main caller and suffi the inner function with
"_locked()" as you did, but I'm fine either ways.

Thanks,
Miquèl

Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[Raghavendra, Vignesh]

Hi,

On 1/29/2026 11:53 PM, Miquel Raynal wrote:
> Hi Andy,
> 
>>> Fix this by factoring out do_write_buffer_locked().
>>
>> ...
>>
>>>  	XIP_INVAL_CACHED_RANGE(map, initial_adr, initial_len);
>>>  	ENABLE_VPP(map);
>>
>> It seems more logical to leave these two in the original call.
>>
>> ...
> 
> [...]
> 
>>> +	DISABLE_VPP(map);
>>
>> Otherwise this will seem dangling here.
>>
>>>  	put_chip(map, chip, cmd_adr);
>>>  	mutex_unlock(&chip->mutex);
>>>  	return ret;
>>
>> ...
>>
>> Another approach is to leave goto as is in the _locked() and move DISABLE_VPP()
>> there.
>>
>> Tell me what do you prefer?
> 
> While I also find more logical to keep the ENABLE_VPP/DISABLE_VPP
> together, I do not mind to see them in one side or the other. I would by
> default let them in the main caller and suffi the inner function with
> "_locked()" as you did, but I'm fine either ways.
> 

Keeping ENABLE_VPP/DISABLE_VPP together along with _locked() suffix for
inner function is cleaner to read.

Regards
Vignesh

Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer_locked() to reduce stack frame

[Andy Shevchenko]

On Sun, Feb 01, 2026 at 03:29:59PM +0530, Raghavendra, Vignesh wrote:
> On 1/29/2026 11:53 PM, Miquel Raynal wrote:

...

> >>>  	XIP_INVAL_CACHED_RANGE(map, initial_adr, initial_len);
> >>>  	ENABLE_VPP(map);
> >>
> >> It seems more logical to leave these two in the original call.
> >>
> >> ...
> > 
> > [...]
> > 
> >>> +	DISABLE_VPP(map);
> >>
> >> Otherwise this will seem dangling here.
> >>
> >>>  	put_chip(map, chip, cmd_adr);
> >>>  	mutex_unlock(&chip->mutex);
> >>>  	return ret;
> >>
> >> ...
> >>
> >> Another approach is to leave goto as is in the _locked() and move DISABLE_VPP()
> >> there.
> >>
> >> Tell me what do you prefer?
> > 
> > While I also find more logical to keep the ENABLE_VPP/DISABLE_VPP
> > together, I do not mind to see them in one side or the other. I would by
> > default let them in the main caller and suffi the inner function with
> > "_locked()" as you did, but I'm fine either ways.
> 
> Keeping ENABLE_VPP/DISABLE_VPP together along with _locked() suffix for
> inner function is cleaner to read.

I just sent a v2 where I kept them in the original call.

-- 
With Best Regards,
Andy Shevchenko