linux-kernel - Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out do_write_buffer

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Message-ID: <aXQak2FKyQpdQW2M@smile.fi.intel.com>
Date: Sat, 24 Jan 2026 03:04:19 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: Miquel Raynal <miquel.raynal@...tlin.com>,
	Richard Weinberger <richard@....at>,
	Vignesh Raghavendra <vigneshr@...com>
Subject: Re: [PATCH v1 1/1] mtd: cfi_cmdset_0001: Factor out
 do_write_buffer_locked() to reduce stack frame

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