[U-Boot] [linux-sunxi] Re: [PATCH v3 0/9] mmc: sunxi: Enable DM_MMC

[Andre Przywara <andre.przywara@arm.com>]

On Fri, 25 Jan 2019 19:01:12 +0800
Chen-Yu Tsai <wens@csie.org> wrote:

Hi,

> On Fri, Jan 25, 2019 at 6:41 PM Jagan Teki
> <jagan@amarulasolutions.com> wrote:
> >
> > On Fri, Jan 25, 2019 at 2:05 PM Chen-Yu Tsai <wens@csie.org>
> > wrote:  
> > >
> > > On Fri, Jan 25, 2019 at 4:27 PM Jagan Teki
> > > <jagan@amarulasolutions.com> wrote:  
> > > >
> > > > On Tue, Jan 22, 2019 at 7:55 AM Chen-Yu Tsai <wens@csie.org>
> > > > wrote:  
> > > > >
> > > > > On Mon, Jan 21, 2019 at 6:31 PM Jagan Teki
> > > > > <jagan@amarulasolutions.com> wrote:  
> > > > > >
> > > > > > Compared to previous version changes[1] this version do
> > > > > > manage ahb clocks/resets via CLK framework.
> > > > > >
> > > > > > This version created changes along with Andre patches to
> > > > > > support clock/resets[2]
> > > > > >
> > > > > > Tested A64, SD, eMMC and respective changes available at
> > > > > > u-boot-sunxi/next
> > > > > >
> > > > > > Changes for v3:
> > > > > > - Handle clock via CLK framework.
> > > > > > Changes for v2:
> > > > > > - update the 'reset enablement' logic to do
> > > > > >   required SoC's
> > > > > >
> > > > > > [1] https://patchwork.ozlabs.org/cover/1026828/
> > > > > > [2] https://patchwork.ozlabs.org/cover/1027850/
> > > > > >
> > > > > > Andre Przywara (2):
> > > > > >   sunxi: clk: add MMC gates/resets
> > > > > >   sunxi: clk: A80: add MMC clock support
> > > > > >
> > > > > > Jagan Teki (7):
> > > > > >   mmc: sunxi: Add A83T emmc compatible
> > > > > >   mmc: sunxi: Add mmc, emmc H5/A64 compatible
> > > > > >   mmc: sunxi: Add DM_MMC support for H6
> > > > > >   mmc: sunxi: Add DM_MMC support for A80
> > > > > >   dm: mmc: sunxi: Add CLK and RESET support
> > > > > >   arm: sunxi: Enable DM_MMC
> > > > > >   arm: dts: sunxi: Enumerate MMC2 as MMC1  
> > > > >
> > > > > Tested-by: Chen-Yu Tsai <wens@csie.org> # on the Bananapi M2M
> > > > >
> > > > > However, the A80 MMC clock patch is still missing code to
> > > > > toggle the upstream bus clock gate and reset control in the
> > > > > CCU.  
> > > >
> > > > Sent it with original mmc clock and reset patch[1], let me know
> > > > your comments.  
> > >
> > > Right. The problem is nowhere in this series are those enabled /
> > > deasserted. The A80 CCU only has one gate & reset for the whole
> > > MMC subsystem, including the MMC config clocks block. Ideally the
> > > driver for that block should enable the gate and deassert the
> > > reset control.  
> >
> > Yes, that same has been included with v3.1 patch which I linked
> > above.  
> 
> The gates/resets are added in that patch. No one is using them. The
> device tree node for the MMC controllers do _not_ reference this clock
> and reset, only the individual ones in the MMC config clock block.
> 
> Unless you are expecting BROM or SPL to have set that up for you,
> which IMO is quite fragile. You could very well boot from SPI or even
> FEL, and it wouldn't be correctly setup, in which case MMC would be
> completely broken.
> 
> FYI the clk-sun9i-mmc driver in Linux deasserts the reset at probe:
> 
>     https://elixir.bootlin.com/linux/latest/source/drivers/clk/sunxi/clk-sun9i-mmc.c#L145
> 
> And enables the bus gate when it needs to toggle bits in its register
> space:
> 
>     https://elixir.bootlin.com/linux/latest/source/drivers/clk/sunxi/clk-sun9i-mmc.c#L53
> 
> This is what is missing. Andre's patch doesn't have them. He
> specifically mentioned this.

But this is addressed by this, isn't it?
https://lists.denx.de/pipermail/u-boot/2019-January/355856.html
(combined with Jagan's addition of the shared gates in v3.1)

Btw.: Somehow I managed to send it from the wrong branch (doesn't even
compile), will send a fix later.

Jagan, we need this patch for A80, and also the pinmux setup patch (1/2
in this series) for it to work. That together with the H3 reset hiccup
should be enough to justify a v4, I believe. Also I had some comments
on your v3 (commit messages outdated, 7/9 too complicated), are you
going to address them?

Meanwhile I prepared a branch to have everything we need:
https://github.com/apritzel/u-boot/commits/sunxi-dm-gates
Please ignore the top 4 commits for now (adding SPI flash support).

Cheers,
Andre.