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SubjectRe: [PATCH v2 01/32] mtd: rawnand: add hooks that may be called during nand_scan()
Hi Miquel,

On Tue, 3 Jul 2018 23:59:58 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> In order to remove the limitation that forbids dynamic allocation in
> nand_scan_ident(), we must create a path that will be the same for all
> controller drivers. The idea is to use nand_scan() instead of the widely
> implemented nand_scan_ident()/nand_scan_tail() couple. In order to
> achieve this, controller drivers will need to adjust some parameters
> between these two functions depending on the NAND chip wired on them.
>
> For that, a hook called ->attach_chip() is created in the
> nand_hw_control structure. This structure may be referenced by two ways:
> 1/ if the driver does not implement its own controller, the
> chip->controller hook is not populated before nand_scan() so it
> cannot be dereferenced: use chip->hwcontrol instead (which is
> statically allocated and will be referenced later by chip->controller
> anyway).
> 2/ through chip->controller if the driver implements its own controller.
>
> Another hook, ->detach_chip() is also introduced in order to clean the
> controller driver's potential allocations in case of failure of
> nand_scan_tail(). There is no need for the controller driver to call the
> ->detach_chip() hook directly upon error after a successful nand_scan().
> In this situation, calling nand_release() as before is enough.
>
> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> ---
> drivers/mtd/nand/raw/nand_base.c | 21 +++++++++++++++++++--
> include/linux/mtd/rawnand.h | 6 ++++++
> 2 files changed, 25 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
> index faac82b1e058..97a74d48b0cf 100644
> --- a/drivers/mtd/nand/raw/nand_base.c
> +++ b/drivers/mtd/nand/raw/nand_base.c
> @@ -6712,11 +6712,23 @@ EXPORT_SYMBOL(nand_scan_tail);
> int nand_scan_with_ids(struct mtd_info *mtd, int maxchips,
> struct nand_flash_dev *ids)
> {
> + struct nand_chip *chip = mtd_to_nand(mtd);
> int ret;
>
> ret = nand_scan_ident(mtd, maxchips, ids);
> - if (!ret)
> - ret = nand_scan_tail(mtd);
> + if (ret)
> + return ret;
> +
> + if (chip->controller->attach_chip) {
> + ret = chip->controller->attach_chip(chip);
> + if (ret)
> + return ret;
> + }
> +
> + ret = nand_scan_tail(mtd);
> + if (ret && chip->controller->detach_chip)
> + chip->controller->detach_chip(chip);
> +
> return ret;
> }
> EXPORT_SYMBOL(nand_scan_with_ids);
> @@ -6744,7 +6756,12 @@ void nand_cleanup(struct nand_chip *chip)
>
> /* Free manufacturer priv data. */
> nand_manufacturer_cleanup(chip);
> +
> + /* Free controller specific allocations after chip identification */
> + if (chip->controller->detach_chip)
> + chip->controller->detach_chip(chip);
> }
> +
> EXPORT_SYMBOL_GPL(nand_cleanup);
>
> /**
> diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
> index 0c6fb316b409..81654211e520 100644
> --- a/include/linux/mtd/rawnand.h
> +++ b/include/linux/mtd/rawnand.h
> @@ -517,11 +517,17 @@ struct nand_id {
> * @wq: wait queue to sleep on if a NAND operation is in
> * progress used instead of the per chip wait queue
> * when a hw controller is available.
> + * @attach_chip: Callback that may be called between nand_detect() and
> + * nand_scan_tail() during nand_scan() (optional).
> + * @detach_chip: Callback that may be called if nand_scan_tail() fails
> + * (optional).
> */
> struct nand_hw_control {
> spinlock_t lock;
> struct nand_chip *active;
> wait_queue_head_t wq;
> + int (*attach_chip)(struct nand_chip *chip);
> + void (*detach_chip)(struct nand_chip *chip);
> };

Can we instead declare a nand_controller_ops struct and then have
nand_hw_control point to it. Something like:

struct nand_controller_ops {
int (*attach_chip)(struct nand_chip *chip);
void (*detach_chip)(struct nand_chip *chip);
};

struct nand_hw_control {
...
const struct nand_controller_ops *ops;
};

>
> static inline void nand_hw_control_init(struct nand_hw_control *nfc)

Regards,

Boris

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