linux-kernel - Re: [PATCH v6 11/23] drivers/fsi: Add master unscan

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Message-ID: <CACPK8Xd5g+tZ7_pTO19YhDhyAUggp2fN2YDp7-1SSP+-9qZu9w@mail.gmail.com>
Date:   Wed, 10 May 2017 17:01:04 +0930
From:   Joel Stanley <joel@....id.au>
To:     Christopher Bostic <cbostic@...ux.vnet.ibm.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>, rostedt@...dmis.org,
        mingo@...hat.com, Greg KH <gregkh@...uxfoundation.org>,
        devicetree <devicetree@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Jeffery <andrew@...id.au>,
        Alistair Popple <alistair@...ple.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH v6 11/23] drivers/fsi: Add master unscan

On Tue, Apr 11, 2017 at 5:16 AM, Christopher Bostic
<cbostic@...ux.vnet.ibm.com> wrote:
> From: Chris Bostic <cbostic@...ux.vnet.ibm.com>
>
> Allow a master to undo a previous scan.  Should a master scan a bus
> twice it will need to ensure it doesn't double register any
> previously detected device.
>
> Signed-off-by: Chris Bostic <cbostic@...ux.vnet.ibm.com>
> Signed-off-by: Joel Stanley <joel@....id.au>
> ---
>  drivers/fsi/fsi-core.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
>
> diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
> index 4da0b030..75d2a88 100644
> --- a/drivers/fsi/fsi-core.c
> +++ b/drivers/fsi/fsi-core.c
> @@ -69,6 +69,7 @@ struct fsi_slave {
>         uint32_t                size;   /* size of slave address space */
>  };
>
> +#define to_fsi_master(d) container_of(d, struct fsi_master, dev)
>  #define to_fsi_slave(d) container_of(d, struct fsi_slave, dev)
>
>  static int fsi_master_read(struct fsi_master *master, int link,
> @@ -491,6 +492,37 @@ static int fsi_master_scan(struct fsi_master *master)
>         return 0;
>  }
>
> +static int __fsi_slave_remove_device(struct device *dev, void *arg)
> +{
> +       device_unregister(dev);
> +       return 0;
> +}
> +
> +static int __fsi_master_remove_slave(struct device *dev, void *arg)
> +{
> +       device_for_each_child(dev, NULL, __fsi_slave_remove_device);
> +       device_unregister(dev);
> +       return 0;
> +}

I can't see why the two above functions to have the __ prefix.

> +
> +static void fsi_master_unscan(struct fsi_master *master)
> +{
> +       device_for_each_child(&master->dev, NULL, __fsi_master_remove_slave);
> +}
> +
> +static ssize_t master_rescan_store(struct device *dev,
> +               struct device_attribute *attr, const char *buf, size_t count)
> +{
> +       struct fsi_master *master = to_fsi_master(dev);
> +
> +       fsi_master_unscan(master);
> +       fsi_master_scan(master);

These function can return errors. Do you want to return those errors
to userspace?

> +
> +       return count;
> +}
> +
> +static DEVICE_ATTR(rescan, 0200, NULL, master_rescan_store);
> +
>  int fsi_master_register(struct fsi_master *master)
>  {
>         int rc;
> @@ -507,7 +539,15 @@ int fsi_master_register(struct fsi_master *master)
>                 return rc;
>         }
>
> +       rc = device_create_file(&master->dev, &dev_attr_rescan);
> +       if (rc) {
> +               device_unregister(&master->dev);
> +               ida_simple_remove(&master_ida, master->idx);
> +               return rc;
> +       }
> +
>         fsi_master_scan(master);
> +
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(fsi_master_register);
> --
> 1.8.2.2
>