linux-kernel - Re: [PATCH v2 4/4] mtd: mtdconcat: add suspend lock handling

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Message-ID: <20211020105547.23ed9324@collabora.com>
Date:   Wed, 20 Oct 2021 10:55:47 +0200
From:   Boris Brezillon <boris.brezillon@...labora.com>
To:     Sean Nyekjaer <sean@...nix.com>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] mtd: mtdconcat: add suspend lock handling

On Wed, 20 Oct 2021 10:45:34 +0200
Sean Nyekjaer <sean@...nix.com> wrote:

> Use MTD hooks to control suspend/resume of MTD devices.

Please explain in great details why this is needed.

> 
> Fixes: 013e6292aaf5 ("mtd: rawnand: Simplify the locking")
> Suggested-by: Boris Brezillon <boris.brezillon@...labora.com>
> Signed-off-by: Sean Nyekjaer <sean@...nix.com>

This patch should be moved earlier (before 'mtd: core: protect access to
MTD devices while in suspend') in the series.

> ---
>  drivers/mtd/mtdconcat.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
> index f685a581df48..1ec36890118f 100644
> --- a/drivers/mtd/mtdconcat.c
> +++ b/drivers/mtd/mtdconcat.c
> @@ -566,9 +566,11 @@ static int concat_suspend(struct mtd_info *mtd)
>  
>  	for (i = 0; i < concat->num_subdev; i++) {
>  		struct mtd_info *subdev = concat->subdev[i];
> -		if ((rc = mtd_suspend(subdev)) < 0)
> +		rc = subdev->_suspend ? subdev->_suspend(subdev) : 0;
> +		if (rc < 0)
>  			return rc;

Same here, you need a fat comment explaining why mtd_suspend() is not
used.

>  	}
> +
>  	return rc;
>  }
>  
> @@ -579,7 +581,8 @@ static void concat_resume(struct mtd_info *mtd)
>  
>  	for (i = 0; i < concat->num_subdev; i++) {
>  		struct mtd_info *subdev = concat->subdev[i];
> -		mtd_resume(subdev);
> +		if (subdev->_resume)
> +			subdev->_resume(subdev);

Ditto.

>  	}
>  }
>