[PATCH 1/6] mmc: sdhci-pltfm: Add structure for host-specific data

[Wolfram Sang]

On Thu, Sep 30, 2010 at 11:54:53AM +0200, Richard Röjfors wrote:
> On 09/30/2010 10:16 AM, Wolfram Sang wrote:
> >Hi Richard,
> >
> >On Wed, Sep 29, 2010 at 11:24:25PM +0200, Richard Röjfors wrote:
> >>On 09/29/2010 10:07 PM, Wolfram Sang wrote:
> >>>We need to carry some information per host, e.g. the clock. Add a
> >>>structure for it and initialize it in the generic part. Also do not use
> >>>the parent of the platform_device (if it is available), this breaks the
> >>>clock-matching on ARM.
> >>
> >>The reason it's there is for instance a case when the shdci device is exposed
> >>from a MFD device which sits on top of PCI. Then the parent (PCI device)
> >>is the device that is DMA capable. This patch will break such usage.
> >
> >I feared that there is a reason. The problem I see is now, that the parent gets
> >always set (from drivers/base/platform.c):
> 
> Then we obviously need to pass more information in the platform_data to be able
> to chose which device to be used.

Yeah, that was my idea, too.

> >So, sdhci-plftm cannot access the platform_data connected to the original
> >platform_device via host->mmc->parent.
> 
> You're right it wouldn't. But isn't it a bit risky even if you could access it,
> in the long the platform_data coild point to something that is in the __devinit section
> or similar?

The use-case we see now is in the custom init() call, i.e. setting up
GPIO, enabling clocks. That is in the same section. Accessing
platform_data later is in deed always risky and should not be done,
sdhci-pltfm is no special case here.

> What about extend the struct you defined with the pieces needed, and access it via
> sdhci_priv?

At the moment, I don't think this is needed. Will think more about it
(and the other comments) next week, already preparing for a long weekend
\o/

Thanks,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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