[PATCH v1 00/15] add basic driver support for broadcom NS3 soc

[Simon Glass]

Hi Rayagonda,

On Wed, 3 Jun 2020 at 03:10, Rayagonda Kokatanur
<rayagonda.kokatanur at broadcom.com> wrote:
>
> Hi Simon,
>
> On Wed, May 20, 2020 at 7:50 PM Simon Glass <sjg at chromium.org> wrote:
> >
> > Hi Rayagonda,
> >
> > On Tue, 19 May 2020 at 23:19, Rayagonda Kokatanur
> > <rayagonda.kokatanur at broadcom.com> wrote:
> > >
> > > Hi Thomas,
> > >
> > > On Wed, May 20, 2020 at 7:34 AM Thomas Fitzsimmons <fitzsim at fitzsim.org> wrote:
> > > >
> > > > Rayagonda Kokatanur <rayagonda.kokatanur at broadcom.com> writes:
> > > >
> > > > > On Tue, May 19, 2020 at 11:01 PM Tom Rini <trini at konsulko.com> wrote:
> > > > >>
> > > > >> On Tue, May 19, 2020 at 10:39:49PM +0530, Rayagonda Kokatanur wrote:
> > > > >> > Hi Tom,
> > > > >> >
> > > > >> >
> > > > >> > On Tue, May 19, 2020 at 12:46 AM Tom Rini <trini at konsulko.com> wrote:
> > > > >> > >
> > > > >> > > On Sun, May 17, 2020 at 01:49:30PM +0530, Rayagonda Kokatanur wrote:
> > > > >> > >
> > > > >> > > > This is the second patch set series prepared on top of the
> > > > >> > > > first patch set ("add initial support for broadcom NS3 soc").
> > > > >> > > >
> > > > >> > > > This patch set will add following,
> > > > >> > > > -dt nodes and defconfig options for basic device like pinctrl,
> > > > >> > > >  gpio, mmc, qspi, wdt, i2c and pcie.
> > > > >> > > > -start wdt service
> > > > >> > > > -Enable GPT commands
> > > > >> > > > -Enable EXT4 and FAT fs support
> > > > >> > >
> > > > >> > > All of the dts changes not in a -u-boot.dtsi file either come from
> > > > >> > > mainline Linux or at least linux-next and have had some level upstream
> > > > >> > > review, right?  Thanks!
> > > > >> >
> > > > >> > Yes. All the DTS changes are merged in the Linux and are available at
> > > > >> > arch/arm64/boot/dts/broadcom/stingray/
> > > > >>
> > > > >> Great.  Please reference the release you're taking these from as that
> > > > >> will make future resyncs easier.  Thanks!
> > > > >
> > > > > It's Linux v5.6.
> > > >
> > > > What's the relationship between e.g., bcm958742t.dts and ns3.dts?  I
> > > > looked at the mainline Linux device trees and I couldn't easily see the
> > > > correspondence.  Will the renaming complicate synchronization?
> > >
> > > Do we need to maintain the same dt file between linux and uboot ?
> > > Also in uboot we don't enable all devices,  how do we handle this ?
> >
> > If there is no U-Boot driver for a particular node then it will be
> > ignored. It is easier to keep them in sync if they are the same in
> > U-Boot and Linux.
> >
> > > Please let me know.
> >
> > That is implied by your question above :-)
>
> NS3 board is derivative of the existing bcm95874t board
> (arch/arm64/boot/dts/broadcom/stingray/bcm958742t.dt)
> Hence we have different dt for NS3 in Linux but it is not yet upstremed.
>
> I compared the dt file size between uboot and Linux.
> Uboot dt size = 9K
> Linux dt size  = 41K (32K extra)
>
> In uboot we have 8MB non-volatile SPI flash memory.
> Out of 8MB, 1.5MB is allocated to fip.bin image and remaining 6.5MB
> space is allocated to other components
> like nitor/bnxt firmware image, DDR shmoo value and for backup image.
>
> uboot.bin is part of the fip.bin image. If we pull Linux dt files this
> will use extra 33K memory of allocated 1.5MB.
> This increase in 33K will reduce total memory availability for u-boot
> and other features (like ARM trusted firmware, Op-TEE OS) development
> in future.
> Hence we anticipate qpsi memory shortage going ahead for new features.
>
> So please let me know your view on maintaining different dt files in uboot.

Sounds like you have plenty of memory, actually. Is U-Boot the first
thing to load?

I think it is important to use the same filename and have the same DT
contents where they are present in U-Boot. But if you want to leave
out nodes, etc., that seems OK to me. It should be easy enough to meld
in the updates later.

I wonder if we should add a way to drop unused nodes for U-Boot
proper, like we do for SPL?

Regards,
Simon