Re: [PATCH] MMC - CONFIG_HOTPLUG support

[Russell King - ARM Linux <linux@arm.linux.org.uk>]

On Mon, Dec 19, 2005 at 01:02:36PM -0300, Anderson.Briglia@indt.org.br wrote:
> On Mon, Dec 19, 2005 at 09:52:59AM -0300, Anderson.Briglia@indt.org.br wrote:
> > I'd like you to explain:
> > 1. what additional support this patch gives us.
> 
> I'm working on MMC hotplug system. This patch is a inicial work to provide
> a minimal kernel configuration hotplug support (and prevent future bugs). 

Either you have hotplug support or you don't.  There is no half-way
house implemented in any kernel subsystem.

> It's necessary more interaction between the MMC core and the MMC block
> driver. When a MMC card is inserted/removed the MMC block driver should
> be informed and adds/removes the device information from the kernel.
> I'm trying to implement this interaction.

This is already implemented.  The MMC block driver will be called via
mmc_blk_probe() when a card is inserted, and via mmc_blk_remove()
when it is removed.

> > 2. what the nature of the optimisation is.
> 
> AFAIK, compiler directives are a guiding for what will/won't be compiled.
> IMHO, if the kernel hotplug support is not selected, doesn't make sense
> that the mmc_bus_hotplug function be compiled. When the MMC core and
> MMC block interaction will be implemented the mmc_bus_hotplug function
> should not be compiled providing that hotplug support.

Right.  You could eliminate the whole function and define mmc_bus_hotplug
to NULL when CONFIG_HOTPLUG is unset, which will eliminate even more
bytes.