[RFC] thoughts about recent Samsung related patches

[Wolfram Sang <w.sang@pengutronix.de>]

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Hi,

while working on the esdhc-controller for the imx-platform, I noticed
the recently comitted changes for Samsung controllers and have some
remarks (sorry for being late):

1) Checking conditions for of host->ops->get_min_clock

The original commit e9510176ff728135383f0cdfc9c90cfe57f9e162 (sdhci: be
more strict with get_min_clock() usage) states why the additional checks
were added. Under this light, it could be argued that commit
cfd1f82f20e0c557a061189f7d8c30d623fbe313 (sdhci: remove useless
set_clock() check) could be reverted and this commit
ce5f036bbbfc6c21d7b55b8fdaa2e2bd56392d94 (sdhci-s3c: add support for the
non standard minimal clock value) could also be reverted if the samsung
platform driver just uses SDHCI_QUIRK_NONSTANDARD_CLOCK without setting
ops->set_clock?

2) 8-Bit data transfer support

The comitted version ae6d6c92212e94b12ab9365c23fb73acc2c3c2e7 (sdhci:
8-bit data transfer width support) looks different from another RFC
posted in February:
http://www.mail-archive.com/linux-mmc@vger.kernel.org/msg01250.html 

As those two already differ, I think it might be wiser to move
8-bit-mode-handling to the platform-specific code? Even the documented
features of a SDHC differ across implementations, I fear side-effects
when using this kind of undocumented feature (official spec says
"reserved" when describing this bit).

3) NO_HI_SPD

Commit 5193250168ccdf87364e35a11965336dc088578c (sdhci: add no hi-speed
bit quirk support) adds a quirk which can be avoided by using
io-accessors like in sdhci-of-esdhc.c. Maybe we can even get rid of
more, older quirks this way to save precious quirk flags. Have to check
that later.

I hope my comments are applicable; because there is no freely available
datasheet, I can't verify all of my assumptions. Looking forward to
comments.

Kind regards,

   Wolfram

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

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