[U-Boot] [PATCH v4] mmc: socfpga_dw_mmc: Enable calibration for drvsel and smplsel

[Marek Vasut <marex@denx.de>]

On Wednesday, December 02, 2015 at 06:52:17 AM, Chin Liang See wrote:

[...]

> > OK, this is bad. Originally, if we didn't specify these in the DT, we
> > would
> > use the default values of 0x3 and 0x0 , but now we do the
> > calibration. I wonder,
> > do we care about DT ABI compatibility on the U-Boot level or not ?
> 
> If the compatibility failed, it will still invoke the calibration to
> get the correct value. Just that its in the cost of boot time.

Hopefully the calibration does it's job then.

> At same time, I am rethinking another email thread on suggesting to put
> this into common dw_mmc code. Here are my proposal

Having this in common code would make sense.

> 1. Put back the correct default value for DT ABI compatiblity
> 2. Adding a node to enable calibration. If node not exist, calibration
> will disabled as default.

But "enable calibration" is not really a hardware property, so it shouldn't
be in the DT. The DT is purely a hardware description and only the smplsel
and drvsel fit into this, some "enable-calibration" does not.

> 3. Some common calibration algo will go into dw_mmc.c
> 4. platform specific such as on configuring the clksel and smplsel will
> be part of platform specific dw_mmc file such as socfpga_dw_mmc.c

OK

> This hope will work for both everyone especially for socfpga and exynos
> platform. Any thoughts?
> 
> Thanks
> Chin Liang

Best regards,
Marek Vasut