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

[Stefan Roese]

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