Re: [PATCH][v2] powerpc/fsl-booke: Add T1040D4RDB/T1042D4RDB board support

[Scott Wood <scottwood@freescale.com>]

On Thu, 2015-07-16 at 04:34 -0500, Jain Priyanka-B32167 wrote:
> 
> -----Original Message-----
> From: Wood Scott-B07421 
> Sent: Wednesday, July 15, 2015 11:17 PM
> To: Jain Priyanka-B32167
> Cc: linuxppc-dev@lists.ozlabs.org
> Subject: Re: [PATCH][v2] powerpc/fsl-booke: Add T1040D4RDB/T1042D4RDB board 
> support
> 
> On Wed, 2015-07-15 at 15:00 +0530, Priyanka Jain wrote:
> > T1040D4RDB/T1042D4RDB are Freescale Reference Design Board which can 
> > support T1040/T1042 QorIQ Power Architecture™ processor respectively
> > 
> > T1040D4RDB/T1042D4RDB board Overview
> > -------------------------------------
> > - SERDES Connections, 8 lanes supporting:
> >         - PCI
> >         - SGMII
> >         - SATA 2.0
> >         - QSGMII(only for T1040D4RDB)
> >     - DDR Controller
> >         - Supports rates of up to 1600 MHz data-rate
> >         - Supports one DDR4 UDIMM
> >     -IFC/Local Bus
> >         - NAND flash: 1GB 8-bit NAND flash
> >         - NOR: 128MB 16-bit NOR Flash
> >     - Ethernet
> >         - Two on-board RGMII 10/100/1G ethernet ports.
> >         - PHY #0 remains powered up during deep-sleep
> >     - CPLD
> >     - Clocks
> >         - System and DDR clock (SYSCLK, “DDRCLK”)
> >         - SERDES clocks
> >     - Power Supplies
> >     - USB
> >         - Supports two USB 2.0 ports with integrated PHYs
> >         - Two type A ports with   5V@1.5Aperport.
> >     - SDHC
> >         - SDHC/SDXC connector
> >     - SPI
> >         - On-board 64MB SPI flash
> >     - I2C
> >         - Devices connected: EEPROM, thermal monitor, VID controller
> >     - Other IO
> >         - Two Serial ports
> >         - ProfiBus port
> > 
> >     Add support for T1040/T1042D4RDB board:
> >     -add device tree
> >     -Add entry in corenet_generic.c
> > 
> > Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
> > ---
> >  Changes for v2:
> >       Incorporated Scott's comments on device tree
> 
> You didn't respond to the comments on the CPLD node.
> [Priyanka]
> T1042D4RDB,  T1040D4RDB are derivatives of same board , CPLD is same for 
> both.
> So, I have moved below node having compatible and reg field together in 
> t104xd4rdb.dtsi.
> Is this fine?
>               cpld@3,0 {
>                       compatible = "fsl,t1040d4rdb-cpld";
>                       reg = <3 0 0x300>;
>               };

If the CPLD image is exactly the same on both, this is fine.

> > +                i2c@118100{
> > +                      mux@77{
> > +                             compatible = "nxp,pca9546";
> > +                             reg = <0x77>;
> > +                             #address-cells = <1>;
> > +                             #size-cells = <0>;
> > +                     };
> > +             };
> 
> A mux with no nodes under it (and yet it has #address-cells/#size-cells)?  
> What is it multiplexing?
> [Priyanka]: PCA9546 is i2c mux device , to which other i2c devices (up-to 8 
> ) can be further connected on output channels
> On T104xD4RDB,  channel 0, 1, 3 line are connected to PEX device, Channel 2 
> to hdmi interface (initialization is done in u-boot only), other channels 
> are grounded. So, as such Linux is not using the second level I2C devices 
> connected on this MUX device. So, I have not shown next level hierarchy.
> Should I replace 'mux' with some other name? . Please suggest.

The device tree describes the hardware, not just what Linux uses... but what I
don't understand is why you describe the mux at all if you're not going to 
describe what goes underneath it.

-Scott