[U-Boot] [PATCH V3 3/8] disk: introduce get_device()

[Stephen Warren <swarren@wwwdotorg.org>]

On 09/21/2012 06:53 AM, Rob Herring wrote:
> On 09/18/2012 05:37 PM, Stephen Warren wrote:
>> From: Stephen Warren <swarren@nvidia.com>
>>
>> This patch introduces function get_device(). This looks up a
>> block_dev_desc_t from an interface name (e.g. mmc) and device number
>> (e.g. 0). This function is essentially the non-partition-specific
>> prefix of get_device_and_partition().

>> +int get_device(const char *ifname, const char *dev_str,
>> +	       block_dev_desc_t **dev_desc)
>> +{
>> +	char *ep;
>> +	int dev;
>> +
> 
> Why don't you look up bootdevice here? That would be more consistent
> behavior.

bootdevice names a partition (or can name a partition), whereas this
function is about retrieving a device handle and never a partition handle.

I'm not sure it makes semantic sense to always fall back to bootdevice
for commands that call get_device() directly. I'd far prefer people to
always just pass the device they want to a command rather than relying
implicitly on environment variables.

If we did read bootdevice here, we'd end up having to read/parse it in
both get_device() and get_device_and_partition(), here to extract just
the device portion and in get_device_and_partition() to extract just the
partition portion. And we'd have to make sure the code here only allowed
the user to specify a partition /if/ this function was called from
get_device_and_partition() and not if a command called it directly. That
all seems a bit complex.