[U-Boot] [PATCH] arm: mvebu: switch clearfog to use device-tree i2c and gpio

[Jon Nettleton]

On Tue, May 29, 2018 at 7:37 AM Stefan Roese <sr at denx.de> wrote:

> On 29.05.2018 07:10, Chris Packham wrote:
> > On Tue, May 29, 2018 at 4:58 PM Baruch Siach <baruch at tkos.co.il> wrote:
> >
> >> Hi Chris,
> >
> >> On Tue, May 29, 2018 at 10:53:38AM +1200, Chris Packham wrote:
> >>> On Tue, May 29, 2018 at 4:11 AM Baruch Siach <baruch at tkos.co.il>
> wrote:
> >>>
> >>>> From: Jon Nettleton <jon at solid-run.com>
> >>>
> >>>> This switches the clearfog boards to use DM based gpio and i2c
> >>>> drivers.  The io expanders are configured via their device-tree
> >>>> entries.
> >>>
> >>>> Signed-off-by: Jon Nettleton <jon at solid-run.com>
> >>>> [baruch: add DT i2c aliases]
> >>>> Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> >>>> ---
> >
> >> [snip]
> >
> >>>> -static struct marvell_io_exp io_exp[] = {
> >>>> -       { 0x20, 2, 0x40 },      /* Deassert both mini pcie reset
> > signals
> >>> */
> >>>> -       { 0x20, 6, 0xf9 },
> >>>> -       { 0x20, 2, 0x46 },      /* rst signals and ena USB3 current
> >>> limiter */
> >>>> -       { 0x20, 6, 0xb9 },
> >>>> -       { 0x20, 3, 0x00 },      /* Set SFP_TX_DIS to zero */
> >>>> -       { 0x20, 7, 0xbf },      /* Drive SFP_TX_DIS to zero */
> >>>> -};
> >>>> -
> >>>
> >>> Will this actually work? As far as I can see u-boot lacks a gpio-hog
> >>> implementation so despite the fact that these are all enumerated in the
> > dts
> >>> they won't have the same effect.
> >>>
> >>> I'd be glad to be proven wrong because I'd like to use a gpio-hog for
> > some
> >>> other boards.
> >
> >> I asked Jon (back on Cc) exactly that before submitting this patch. His
> >> response:
> >
> >>     I think that is fine. They can still be toggled and controlled via
> the
> > gpio
> >>     interface within u-boot. I assume once a proper patch is mainline
> this
> > will
> >>     just start to work.
> >
> >> My testing showed now regression because of this patch.
> >
> > OK. Did you test with a power cycle? I know some of the pca gpio chips
> > don't have a reset line so the state may be different depending on if you
> > power cycled or just used the reset/reboot command. It could also be that
> > u-boot doesn't access these devices so there's no problem.
> >
> > I kinda was hoping for "here's a gpio-hog implementation @
> patchwork/1234"
> > :) but I guess I'll have to look into making one myself.
>
> I would prefer to not drop these I2C accesses from the ClearFog board
> C code now, as we don't have a way to do this via the DT right now.
> Why are they dropped with this patch? Because of the I2C API
> changes? Please move to the DM I2C API then (dm_i2c_read/write).
>
> Thanks,
> Stefan
>

Stefan,

These do not need to be setup independently any longer.  Moving to DM_GPIO
allows the PCI driver to handle the reset lines.  The USB3 reset and
current limiter should be handled in board_xhci_enable() which can be done,
although I have never seen an issue using USB3 with this configuration
since I have implemented it.  Since u-boot doesn't understand the SFP setup
at all I would prefer if it left SFP configuration up to Linux.  Just
enabling TX on an SFP module without understanding any of the specifics of
the configuration is a bit dangerous when dealing with modules that aren't
just SGMII 1000base-Tx.

I will follow up with a patch for board_xhci_enable().

Thanks,
Jon