Re: staging: vme_user: accept bus_num of zero

[Aaron Sierra]

- Original Message -
> From: "Martyn Welch" 
> Sent: Thursday, September 8, 2016 2:17:35 PM

> On Fri, Sep 02, 2016 at 03:59:45PM -0500, Aaron Sierra wrote:
>> The driver's bus_num parameter is used to select a VME bus during probe.
>> This parameter is used both as a boolean to indicate that probing should
>> occur as well as which bus should be probed. However, the first bus in
>> the system is bus zero, so this method prevents the first bus from being
>> accepted during probe.
>> 
> 
> Umm, no. The array "bus" holds the buses that should be probed, bus_num
> holds the length of the array passed.

Martyn,
Of course you're right about this patch being wrong. I'm sorry for the
noise. I'm not sure how I missed your patch "VME: Provide access to VME
bus enumeration and fix vme_user match function" that addressed my
concern about "bus=0" not working which I raised back in 2013 with my
patch "vme_user: Remove superfluous bus module parameter":

http://www.spinics.net/lists/linux-driver-devel/msg39943.html

-Aaron S

> 
>> This patch changes the default value of bus_num to -1, so that any
>> number in the range of 0 to VME_USER_BUS_MAX will be accepted during
>> probe.
>> 
>> Signed-off-by: Aaron Sierra 
>> ---
>>  drivers/staging/vme/devices/vme_user.c | 9 +
>>  1 file changed, 1 insertion(+), 8 deletions(-)
>> 
>> diff --git a/drivers/staging/vme/devices/vme_user.c
>> b/drivers/staging/vme/devices/vme_user.c
>> index b95883b..fc660bd 100644
>> --- a/drivers/staging/vme/devices/vme_user.c
>> +++ b/drivers/staging/vme/devices/vme_user.c
>> @@ -45,7 +45,7 @@
>>  static const char driver_name[] = "vme_user";
>>  
>>  static int bus[VME_USER_BUS_MAX];
>> -static unsigned int bus_num;
>> +static int bus_num = -1;
>>  
>>  /* Currently Documentation/devices.txt defines the following for VME:
>>   *
>> @@ -735,12 +735,6 @@ static int __init vme_user_init(void)
>>  
>>  pr_info("VME User Space Access Driver\n");
>>  
>> -if (bus_num == 0) {
>> -pr_err("No cards, skipping registration\n");
>> -retval = -ENODEV;
>> -goto err_nocard;
>> -}
>> -
>>  /* Let's start by supporting one bus, we can support more than one
>>   * in future revisions if that ever becomes necessary.
>>   */
>> @@ -763,7 +757,6 @@ static int __init vme_user_init(void)
>>  return retval;
>>  
>>  err_reg:
>> -err_nocard:
>>  return retval;
>>  }
>>  
>> --
>> 1.9.1
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Re: staging: vme_user: accept bus_num of zero

[Martyn Welch]

On Fri, Sep 02, 2016 at 03:59:45PM -0500, Aaron Sierra wrote:
> The driver's bus_num parameter is used to select a VME bus during probe.
> This parameter is used both as a boolean to indicate that probing should
> occur as well as which bus should be probed. However, the first bus in
> the system is bus zero, so this method prevents the first bus from being
> accepted during probe.
> 

Umm, no. The array "bus" holds the buses that should be probed, bus_num
holds the length of the array passed.

> This patch changes the default value of bus_num to -1, so that any
> number in the range of 0 to VME_USER_BUS_MAX will be accepted during
> probe.
> 
> Signed-off-by: Aaron Sierra 
> ---
>  drivers/staging/vme/devices/vme_user.c | 9 +
>  1 file changed, 1 insertion(+), 8 deletions(-)
> 
> diff --git a/drivers/staging/vme/devices/vme_user.c 
> b/drivers/staging/vme/devices/vme_user.c
> index b95883b..fc660bd 100644
> --- a/drivers/staging/vme/devices/vme_user.c
> +++ b/drivers/staging/vme/devices/vme_user.c
> @@ -45,7 +45,7 @@
>  static const char driver_name[] = "vme_user";
>  
>  static int bus[VME_USER_BUS_MAX];
> -static unsigned int bus_num;
> +static int bus_num = -1;
>  
>  /* Currently Documentation/devices.txt defines the following for VME:
>   *
> @@ -735,12 +735,6 @@ static int __init vme_user_init(void)
>  
>   pr_info("VME User Space Access Driver\n");
>  
> - if (bus_num == 0) {
> - pr_err("No cards, skipping registration\n");
> - retval = -ENODEV;
> - goto err_nocard;
> - }
> -
>   /* Let's start by supporting one bus, we can support more than one
>* in future revisions if that ever becomes necessary.
>*/
> @@ -763,7 +757,6 @@ static int __init vme_user_init(void)
>   return retval;
>  
>  err_reg:
> -err_nocard:
>   return retval;
>  }
>  
> -- 
> 1.9.1
> 
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