[U-Boot] [PATCH 00/25] sunxi: Enable DM_MMC for U-Boot proper

[Maxime Ripard]

On Mon, Jul 16, 2018 at 04:35:09PM +0800, Chen-Yu Tsai wrote:
> On Mon, Jul 16, 2018 at 4:19 PM, Jagan Teki <jagan at amarulasolutions.com> wrote:
> > Enabling DM_MMC is not straight forward for Allwinner SoC's to
> > make proper compatibility in mmc driver vs DT nodes.
> >
> > Existing dm code for ahb gate clock will be suitable to handle
> > sun4i,5i,6i and 7i U-Boot specific mmc dt nodes, which are different
> > from Linux in terms of clocks phandle notation.
> >
> > U-Boot DT clocks phandle follow direct ahb and clock address on
> > node definition with specific bit position, but Linux clocks phandle
> > follow macros to define AHB and MMC clocks so-that the ccu driver
> > will set the bits accordingly.
> 
> And that has been deprecated upstream.
> 
> > Clocks phandle notations in U-Boot for higher Allwinner SoC start
> > from sun8i, sun50i are following Linux notation so-that both Linux
> > and U-Boot can have common node definition.
> 
> So basically you're saying the additional code for clock/reset
> handling through the device tree only works for half of the SoCs,
> based on a deprecated device tree binding. Which means we're
> going to throw it out some time in the future. Is it worth the
> churn of driver and device tree changes?
> 
> IMHO the new clock handling code is no better than the old. The only
> thing that has changed is how the clock register address is derived.
> Not even the index numbers, which BTW are actual bit offsets, for
> the AHB gates from the device tree are used. Neither is the device
> tree used for the AHB resets.

I'd say that it's even worse. We want an actual, common, clock
driver. Not a quick hack that doesn't solve any of the issues we're
facing.

Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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