Re: [PATCH v2 1/1] spi: dw: Make debugfs name unique between instances

[Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>]

G'day Andy,

On 4/01/2017 07:05, Andy Shevchenko wrote:
> On Wed, Jan 4, 2017 at 1:02 AM, Andy Shevchenko
> <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> On Tue, Jan 3, 2017 at 6:54 AM, Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org> wrote:
>>> Some system have multiple dw devices. Currently the driver uses a
>>> fixed name for the debugfs dir. Append bus_num to the debugfs dir
>>> name to make it unique.
>>>
>>
>> Reviewed-by: Andy Shevchenko <andy.shevchenko-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>
> Ah, hold on.
> dws->name is exactly what you are trying to re-invent here. Just use
> it directly.
>
I did try that initially.
However when I used that they where all named dw_spi65535.

This seems to be because bus_num is set to -1 ion the call to dw_spi_add_host.
Which results in dynamic bus_num assignment in the call to devm_spi_register_master.

Moving 'snprintf(dws->name, sizeof(dws->name), "dw_spi%d", dws->bus_num);' to after
devm_spi_register_master results in a warning being emitting when request_irq is called
about an emit string at :
WARNING: CPU: 0 PID: 1 at fs/proc/generic.c:369 __proc_create+0x1e8/0x1f0

cat /proc/interrupts currently also shows dw_spi65535

Rewrite dws->name after devm_spi_register_master is called fixes /proc/interrupts
And it could then be used in debugfs.
But does not fix the filename in /proc/irq/<num>/dw_spi65535

I couldn't see a safe workaround with dws->name
Unless we can move the request_irq to after devm_spi_register_master

Thoughts?



>
>>
>>> Signed-off-by: Phil Reid <preid-qgqNFa1JUf/o2iN0hyhwsIdd74u8MsAO@public.gmane.org>
>>> ---
>>>
>>> Notes:
>>>     Changes from v1:
>>>     - Reduce buffer size to 32.
>>>     - Use bus_num instead of device name.
>>>
>>>  drivers/spi/spi-dw.c | 5 ++++-
>>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
>>> index 27960e4..77439ac 100644
>>> --- a/drivers/spi/spi-dw.c
>>> +++ b/drivers/spi/spi-dw.c
>>> @@ -107,7 +107,10 @@ static ssize_t dw_spi_show_regs(struct file *file, char __user *user_buf,
>>>
>>>  static int dw_spi_debugfs_init(struct dw_spi *dws)
>>>  {
>>> -       dws->debugfs = debugfs_create_dir("dw_spi", NULL);
>>> +       char name[32];
>>> +
>>> +       snprintf(name, 32, "dw_spi%d", dws->master->bus_num);
>>> +       dws->debugfs = debugfs_create_dir(name, NULL);
>>>         if (!dws->debugfs)
>>>                 return -ENOMEM;
>>>
>>> --
>>> 1.8.3.1
>>>
>>> --
>>> To unsubscribe from this list: send the line "unsubscribe linux-spi" in
>>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
>>
>>
>>
>> --
>> With Best Regards,
>> Andy Shevchenko
>
>
>


-- 
Regards
Phil Reid

--
To unsubscribe from this list: send the line "unsubscribe linux-spi" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html