[U-Boot] [PATCH V3] imx: mx25: Remove SION bit in all pin-mux that are safe

[Michael Nazzareno Trimarchi]

Hi Stefano

Do I need to resend with you in CC?

For some reason I forget to include you

Michael

On Fri, Jan 26, 2018 at 12:00 PM, Benoît Thébaudeau <benoit at wsystem.com> wrote:
> On 25/01/2018 at 22:48, Benoît Thébaudeau wrote:
>> On Thu, Jan 25, 2018 at 2:06 PM, Michael Trimarchi
>> <michael at amarulasolutions.com> wrote:
>>> SION bit should be used in the situation that we need
>>> to read back the value of a pin and should not be set by
>>> default macro.
>>>
>>> We get some malfunction as raised by following thread
>>>
>>> https://www.spinics.net/lists/linux-usb/msg162574.html
>>>
>>> As reported by this application note:
>>> https://www.nxp.com/docs/en/application-note/AN5078.pdf
>>>
>>> The software input on (SION) bit is an option to force an input
>>> path to be active regardless of the value driven by the
>>> corresponding module. It is used when the nature direction
>>> of a pin depending on selected alternative function is an output,
>>> but it is needed to read the real logic value on a pin.
>>>
>>> The SION bit can be used in:
>>> • Loopback: the module of a selected alternative function drives
>>> the pad and also receives the pad value as an input
>>> • GPIO capture: the module of a selected alternative function
>>> drives the pin and the value is captured by the GPIO
>>>
>>> SION bit is not necessary when the pin is configured as a peripheral
>>> apart specific silicon bug. If an application needs to have this
>>> set, this should be done in board file or in dts file
>>>
>>> Signed-off-by: Michael Trimarchi <michael at amarulasolutions.com>
>>
>> [...]
>>
>> I have now tested the following peripherals on i.MX25 without any SION
>> bit set: AUDMUX/SSI, eSDHC, FEC (except PHY access for which MDIO
>> might have an issue without SION; Ethernet works but I have not
>> checked whether this is possible at least partially without access to
>> the PHY registers), GPIO, I2C, SLCDC, UART, and USB. Everything worked
>> fine except the lack of SION for eSDHC CMD, which is true for all
>> eSDHC instances (and not only for eSDHC1, so Linux's
>> arch/arm/boot/dts/imx25-pinfunc.h should be fixed). Therefore, SION is
>> mandatory for all the eSDHC CMD functions in
>> arch/arm/include/asm/arch-mx25/iomux-mx25.h, but it can be removed for
>> everything else (I still have to carry out one more test to confirm
>> this for FEC MDIO), and moved to the board files if necessary (but I
>> don't think that any mainline board code is doing something fancy
>> enough to need it).
>
> I confirm that FEC RMII register access works fine without setting SION for
> MDIO.
>
> Benoît



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| Michael Nazzareno Trimarchi                     Amarula Solutions BV |
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