RE: [PATCH 04/10] ravb: Add support for RZ/G2L SoC

From: Biju Das <biju.das.jz@bp.renesas.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Sergey Shtylyov <s.shtylyov@omp.ru>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Sergei Shtylyov <sergei.shtylyov@gmail.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Sergey Shtylyov <s.shtylyov@omprussia.ru>,
	Adam Ford <aford173@gmail.com>, Andrew Lunn <andrew@lunn.ch>,
	Yuusuke Ashizuka <ashiduka@fujitsu.com>,
	Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"linux-renesas-soc@vger.kernel.org" 
	<linux-renesas-soc@vger.kernel.org>,
	Chris Paterson <Chris.Paterson2@renesas.com>,
	Biju Das <biju.das@bp.renesas.com>,
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@bp.renesas.com>
Subject: RE: [PATCH 04/10] ravb: Add support for RZ/G2L SoC
Date: Mon, 4 Oct 2021 07:49:27 +0000	[thread overview]
Message-ID: <OS0PR01MB5922532F81F63129BD8F1BB386AE9@OS0PR01MB5922.jpnprd01.prod.outlook.com> (raw)
In-Reply-To: <CAMuHMdXSeCA+27xiXAgwRUi4wFukXkrttTvnEGhZAtq7p_trCw@mail.gmail.com>

Hi Geert,

Thanks for the feedback

> Subject: Re: [PATCH 04/10] ravb: Add support for RZ/G2L SoC
> 
> Hi Biju,
> 
> On Sun, Oct 3, 2021 at 8:51 AM Biju Das <biju.das.jz@bp.renesas.com>
> wrote:
> > > Subject: Re: [PATCH 04/10] ravb: Add support for RZ/G2L SoC On
> > > 10/1/21 6:06 PM, Biju Das wrote:
> > > > RZ/G2L SoC has Gigabit Ethernet IP consisting of Ethernet
> > > > controller (E-MAC), Internal TCP/IP Offload Engine (TOE) and
> > > > Dedicated Direct memory access controller (DMAC).
> > > >
> > > > This patch adds compatible string for RZ/G2L and fills up the
> > > > ravb_hw_info struct. Function stubs are added which will be used
> > > > by gbeth_hw_info and will be filled incrementally.
> > >
> > >    I've always been against this patch -- we get a support for the
> > > GbEther whihc doesn't work after this patch. I believe we should
> > > have the GbEther support in the last patch. of the overall series.
> >
> > This is the common practice. We use bricks to build a wall. The
> > function stubs are just Bricks.
> >
> > After filling stubs, we will add SoC dt and board DT, after that one
> > will get GBsupport on RZ/G2L platform.
> 
> Not "after", but "in parallel".  The stubs will be filled in through the
> netdev tree (1), while SoC DT and board DT will go through the renesas-
> devel and soc trees (2).
> 
> So our main worry is: what happens if you have (2) but not (1)?

Please find the test cases

Case a) (1) and then (2) RootFS mounted on NFS
----------------------------------------------------

root@smarc-rzg2l:~# cat /proc/cmdline
ignore_loglevel nfsrootdebug root=/dev/nfs rw nfsroot=192.168.10.1:/tftpboot/RZ-G2L,nfsvers=3 ip=192.168.10.2
root@smarc-rzg2l:~#

Case b) Have (2) but not (1)? RootFS mounted on USB
----------------------------------------------------

root@smarc-rzg2l:~# cat /proc/cmdline
rw rootwait earlycon root=/dev/sda1
root@smarc-rzg2l:~#

Case c) Have (2) but not (1)? RootFS mounted on NFS
---------------------------------------------------

It stops booting as we haven't filled RX stubs.

[    4.457432]  sda: sda1
[    4.465909] sd 0:0:0:0: [sda] Attached SCSI removable disk

If you look at Case B, that is the current case, which boots without any issues. There is no regression
at all with the current changes submitted.

The only issue is mounting with NFS which won't work as we haven't filled stubs to get full functionality.

Regards,
Biju