[PATCH 11/15] wireless: wl1271: introduce platform device support

[Madhusudhan]

> -----Original Message-----
> From: Nicolas Pitre [mailto:nico at fluxnic.net]
> Sent: Wednesday, July 07, 2010 9:03 AM
> To: Roger Quadros
> Cc: Hunter Adrian (Nokia-MS/Helsinki); Ohad Ben-Cohen; linux-
> wireless at vger.kernel.org; linux-mmc at vger.kernel.org; linux-
> omap at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux at arm.linux.org.uk; Chikkature Rajashekar Madhusudhan; Coelho Luciano
> (Nokia-MS/Helsinki); akpm at linux-foundation.org; San Mehat
> Subject: Re: [PATCH 11/15] wireless: wl1271: introduce platform device
> support
> 
> On Wed, 7 Jul 2010, Roger Quadros wrote:
> 
> > On 07/06/2010 10:51 PM, Hunter Adrian (Nokia-MS/Helsinki) wrote:
> > > For eMMC in omap_hsmmc, this is all done via claim_host / release_host
> > > which call ->enable() / ->disable() methods.  omap_hsmmc makes use of
> > > mmc_power_restore_host() which calls host->bus_ops->power_restore()
> > > which is not implemented for SDIO, but for MMC and SD it reinitializes
> > > the card.
> 
> This is IMHO a really bad design.  The power control decision has to
> come from the top, not from the bottom.  And certainly not with a
> U-turn dependency the omap_hsmmc is using.
> 
> I regret to say this, but the omap_hsmmc driver is becoming a total
> mess.  The host controller driver has to be a dumb interface serving
> requests from the hardware used by the upper layer stack, not the place
> where decisions such as power handling should be made.  Think of it like
> an ethernet driver.  No ethernet driver in Linux is telling the IP stack
> when to shut down.
> 

The point is that MMC/SD core files were patched to provide this kind of a
support. Any controller driver can use that framework today, right?. As an
example omap_hsmmc driver was patched and it works fine.

Why blame the controller driver for using a support provided by core files?

Regards,
Madhu

> > Shouldn't the power control intelligence (i.e. when to turn power
> ON/OFF) lie
> > with the bus drivers?
> 
> Absolutely!  And in the SDIO case that should lie with each function
> drivers.  Please let's stop this omap_hsmmc madness.
> 
> 
> Nicolas