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

[Rayagonda Kokatanur]

Hi Simon,

On Thu, Jun 4, 2020 at 8:30 AM Simon Glass <sjg at chromium.org> wrote:
>
> 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?

Thank you for your suggestion.

Right now linux dt files are not upstremed.
Upstreaming linux dt files first and then using the same in uboot will
delay these uboot patch merge.
Hence I am planning to do following,
1. Use one sample dt file with just few basic nodes so that uboot can
be built without any issues.
2. Parallely start linux dt file upstream.
3. Once the linux dt file gets merged, I will pull them into uboot and
submit a patch.

Please let me know.

Best regards,
Rayagonda


>
> Regards,
> Simon