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

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Message-Id: <875f5079-0157-6f86-5020-7cfab891664f@linux.vnet.ibm.com>
Date:   Wed, 10 May 2017 13:33:27 -0500
From:   Christopher Bostic <cbostic@...ux.vnet.ibm.com>
To:     Joel Stanley <joel@....id.au>
Cc:     Rob Herring <robh+dt@...nel.org>, jk@...abs.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 5/10/17 2:31 AM, Joel Stanley wrote:
> 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.

Jeremy Kerr had introduced this convention.  Jeremy can you comment on 
this?

>
>> +
>> +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?

That would be the best approach yes... Will change.

>
>> +
>> +       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
>>