Re: [PATCH edk2-platforms 1/5] Silicon/NXP/LS1043A: Fix the Platform PLL calculation

["Pankaj Bansal" <pankaj.bansal@nxp.com>]

> On Tue, Jun 02, 2020 at 18:54:59 +0530, Pankaj Bansal wrote:
> > From: Pankaj Bansal <pankaj.bansal@nxp.com>
> >
> > for LS1043A SOC the DCFG registers are read in big endian format.
> > However current Platofmr PLL calculation is being done assuing the
> 
>                   Platform?                              assuming

yes. typo mistake.

> 
> > little endian format.
> >
> > Fix the Platform PLL calculation
> 
> OK, now I'm confused.
> DCFG is read using the DcfgRead32 function, which is supposed to
> handle the endianness issue.
> 
> Ls1043a builds with
>   gNxpQoriqLsTokenSpaceGuid.PcdDcfgBigEndian|TRUE
> which means GetMmioOperations() returns the byte-swapping versions.
> 
> Please clarify.

OK. so this might be little confusing, so bear with me.
The reset configuration word (RCW) is 512 bits (1024 bits in LS2088 / LS2160) long and contains all necessary configuration information for
the chip. RCW data is read from external memory (Nor flash or SD/eMMC card or I2c eeprom)  and written to the RCW status registers
(RCWSR) contained in the Device Configuration and Pin Control module (DCSR), after which the device is configured as specified in the RCW.

The PreBoot Loader (PBL) fetches RCW data from the source memory device and writes it to the RCW status registers.
Now the PBL fetches the data from flash in little endian format and writes it to the DCSR registers in little endian format always.
This steps is same for all SOCs (LX2160 / LS1043 / LS1046 / LS2088).

Now in SOCs where DCSR space is big endian (LS1043 / LS1046), we read the RCWSR registers in big endian fashion.
This causes the bit position to be reversed.

In SOCs where DCSR space is little endian (LS2088 / LX2160), we read the RCWSR registers in little endian fashion.
That is why the bit position is correct.

> 
> /
>     Leif
> 
> > Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>
> > ---
> >  Silicon/NXP/LS1043A/Include/Soc.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/Silicon/NXP/LS1043A/Include/Soc.h
> b/Silicon/NXP/LS1043A/Include/Soc.h
> > index 97a77d3f5da6..afcd9da34cda 100644
> > --- a/Silicon/NXP/LS1043A/Include/Soc.h
> > +++ b/Silicon/NXP/LS1043A/Include/Soc.h
> > @@ -48,7 +48,7 @@
> >  /**
> >    Reset Control Word (RCW) Bits
> >  **/
> > -#define SYS_PLL_RAT(x)  (((x) & 0x7c) >> 2) // Bits 2-6
> > +#define SYS_PLL_RAT(x)  (((x) >> 25) & 0x1f) // Bits 2-6
> >
> >  typedef NXP_LAYERSCAPE_CHASSIS2_DEVICE_CONFIG
> LS1043A_DEVICE_CONFIG;
> >
> > --
> > 2.17.1
> >