Re: [PATCH] mtd: rawnand: gpmi: add debugfs entry for BCH geometry

From: Miquel Raynal <miquel.raynal@bootlin.com>
To: han.xu@oss.nxp.com
Cc: Richard Weinberger <richard@nod.at>,
	 Vignesh Raghavendra <vigneshr@ti.com>,
	 imx@lists.linux.dev,  linux-mtd@lists.infradead.org,
	linux-kernel@vger.kernel.org,  Han Xu <han.xu@nxp.com>
Subject: Re: [PATCH] mtd: rawnand: gpmi: add debugfs entry for BCH geometry
Date: Wed, 29 Jul 2026 10:05:36 +0200	[thread overview]
Message-ID: <87jyqenru7.fsf@bootlin.com> (raw)
In-Reply-To: <20260727-nand_debugfs-v1-1-7cba1ceab5ee@nxp.com> (han xu's message of "Mon, 27 Jul 2026 16:09:08 -0500")

Hi Han,

On 27/07/2026 at 16:09:08 -05, han.xu@oss.nxp.com wrote:

> From: Han Xu <han.xu@nxp.com>
>
> Export the BCH geometry parameters via debugfs to aid debugging and
> provide the necessary information for legacy kobs-ng tool. The debugfs
> directory "gpmi-nand" is created under the root debugfs tree, exposing:
>
> bch_geometry  - blob containing the struct bch_geometry fields
> raw_mode      - flag indicating raw mode status
>
> The implementation is guarded with #ifdef CONFIG_DEBUG_FS to avoid
> build failures when debugfs is disabled.
>
> Signed-off-by: Han Xu <han.xu@nxp.com>
> ---
>  drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> index c1f766cb225aa..3ceb8df7f8f93 100644
> --- a/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> +++ b/drivers/mtd/nand/raw/gpmi-nand/gpmi-nand.c
> @@ -7,6 +7,7 @@
>   */
>  #include <linux/cleanup.h>
>  #include <linux/clk.h>
> +#include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/slab.h>
>  #include <linux/sched/task_stack.h>
> @@ -732,6 +733,26 @@ static int common_nfc_set_geometry(struct gpmi_nand_data *this)
>  	return err;
>  }
>  
> +#ifdef CONFIG_DEBUG_FS
> +static struct debugfs_blob_wrapper dbg_bch_geo;

Why do you use a static variable for that? This should be dynamically
allocated otherwise if you ever have more than one device you'll have
strange results.

> +static void bch_create_debugfs(struct gpmi_nand_data *this)
> +{
> +	struct bch_geometry *bch_geo = &this->bch_geometry;
> +	struct dentry *dbg_root;
> +
> +	dbg_root = debugfs_create_dir("gpmi-nand", NULL);
> +	dbg_bch_geo.data = (void *)bch_geo;
> +	dbg_bch_geo.size = sizeof(struct bch_geometry);
> +	debugfs_create_blob("bch_geometry", 0444, dbg_root, &dbg_bch_geo);
> +	/* create raw mode flag */
> +	debugfs_create_file_full("raw_mode", 0444, dbg_root, NULL, NULL,
> NULL);

I am not sure about the _full suffix, bug debufs_create_file() is enough
here, provided that you give a tangible variable to expose.

> +}
> +#else
> +static void bch_create_debugfs(struct gpmi_nand_data *this)
> +{
> +}
> +#endif /* CONFIG_DEBUG_FS */
> +
>  /* Configures the geometry for BCH.  */
>  static int bch_set_geometry(struct gpmi_nand_data *this)
>  {
> @@ -2282,6 +2303,9 @@ static int gpmi_init_last(struct gpmi_nand_data *this)
>  	if (ret)
>  		return ret;
>  
> +	/* save BCH geometry to debugfs if CONFIG_DEBUG_FS is enabled */
> +	bch_create_debugfs(this);

You need to call debugfs_remove_recursive() in the removal path.

> +
>  	/* Init the nand_ecc_ctrl{} */
>  	ecc->read_page	= gpmi_ecc_read_page;
>  	ecc->write_page	= gpmi_ecc_write_page;
>
> ---
> base-commit: f97bdc8ec1dc7b33781a702eeba55326c206be56
> change-id: 20260727-nand_debugfs-74d6d6ba52df
>
> Best regards,

Thanks,
Miquèl

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