[U-Boot] [PATCH] arch: ifc: update the IFC IP input clock

[Prabhakar Kushwaha]

> -----Original Message-----
> From: york sun
> Sent: Wednesday, September 07, 2016 9:17 PM
> To: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>; u-
> boot at lists.denx.de
> Subject: Re: [PATCH] arch: ifc: update the IFC IP input clock
> 
> On 09/06/2016 07:42 PM, Prabhakar Kushwaha wrote:
> >
> >> -----Original Message-----
> >> From: york sun
> >> Sent: Tuesday, September 06, 2016 9:10 PM
> >> To: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>; u-
> >> boot at lists.denx.de
> >> Subject: Re: [PATCH] arch: ifc: update the IFC IP input clock
> >>
> >> On 09/06/2016 04:15 AM, Prabhakar Kushwaha wrote:
> >>> IFC IP clock is always a constant divisor of platform clock
> >>> pre-defined per SoC. Clock Control register (CCR) used in
> >>> current implementation governs IFC IP output clock.
> >>>
> >>> So update IFC IP clock to be defined as per predefined clock
> >>> divisor of platform clock.
> >>>
> >>> Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>
> >>> ---
> >>>  README                                              |  3 +++
> >>>  arch/arm/cpu/armv7/ls102xa/clock.c                  | 10 ++--------
> >>>  arch/arm/cpu/armv8/fsl-layerscape/fsl_lsch2_speed.c | 10 ++--------
> >>>  arch/arm/cpu/armv8/fsl-layerscape/fsl_lsch3_speed.c | 10 ++--------
> >>>  arch/arm/include/asm/arch-fsl-layerscape/config.h   |  3 +++
> >>>  arch/arm/include/asm/arch-ls102xa/config.h          |  1 +
> >>>  arch/powerpc/cpu/mpc85xx/speed.c                    | 10 ++--------
> >>>  arch/powerpc/include/asm/config_mpc85xx.h           |  9 +++++++++
> >>>  8 files changed, 24 insertions(+), 32 deletions(-)
> >>
> >> Prabkahar,
> >>
> >> Two concerns here
> >>
> >> 1, it is not only IFC for powerpc. Older SoCs have local bus. That's why
> >> the variable is named freq_localbus..
> >>
> >
> > As per my understanding, Issue is valid for eLBC SoC also.
> > Just wanted to confirm from internal IP team before spinning patch to fix it.
> >
> >> 2, what's the reason for this change? Is it wrong to use ccr to
> >> calculate the clock? Or is it because recent Layerscape SoCs have
> >> platform PLL different from platform clock? If the latter, can we limit
> >> the fix to platform clock and not changing powerpc?
> >>
> >
> > CCR governs the IFC output clock.
> > This clock is used for synchronous NOR, NAND flashes. It is nowhere govern
> IFC IP internal clock.
> >
> > It is true since conception of IFC. Unfortunately code written is wrong since
> P1010.
> > It is confusing everyone.
> >
> 
> Are you saying the freq_localbus should be the internal clock, not
> output clock? As far as I can remember, this variable has always be used
> for output clock since 85xx. I am open to the idea to change to internal
> clock only if it makes sense. Browsing the code, I see this variable is
> used for information only, except for setting arch.lbc_clk.
> 
 
Everyone believe it to be IFC internal clock not the output clock. 
As I always used to get query from customers about wrong IFC speed.  

So better to print IP clock to avoid any confusion.
IFC output clock will be printed when it is actually being used during synchronous NOR, syn NAND.
Please note it is currently not being supported by IFC. 

--prabhakar