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Message-ID: <CAMdnO-JKfi0hqaR5zrzzv6j-c6OhH-LTZT5WWBCFDOG_+ZxTeQ@mail.gmail.com>
Date: Fri, 2 Aug 2024 15:06:05 -0700
From: Jitendra Vegiraju <jitendra.vegiraju@...adcom.com>
To: Serge Semin <fancer.lancer@...il.com>
Cc: netdev@...r.kernel.org, alexandre.torgue@...s.st.com, joabreu@...opsys.com,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
mcoquelin.stm32@...il.com, bcm-kernel-feedback-list@...adcom.com,
richardcochran@...il.com, ast@...nel.org, daniel@...earbox.net,
hawk@...nel.org, john.fastabend@...il.com, linux-kernel@...r.kernel.org,
linux-stm32@...md-mailman.stormreply.com,
linux-arm-kernel@...ts.infradead.org, bpf@...r.kernel.org, andrew@...n.ch,
linux@...linux.org.uk, horms@...nel.org, florian.fainelli@...adcom.com
Subject: Re: [PATCH net-next v3 0/3] net: stmmac: Add PCI driver support for BCM8958x
On Fri, Aug 2, 2024 at 3:02 AM Serge Semin <fancer.lancer@...il.com> wrote:
>
> Hi Jitendra
>
> On Thu, Aug 01, 2024 at 08:18:19PM -0700, jitendra.vegiraju@...adcom.com wrote:
> > From: Jitendra Vegiraju <jitendra.vegiraju@...adcom.com>
> >
> > This patchset adds basic PCI ethernet device driver support for Broadcom
> > BCM8958x Automotive Ethernet switch SoC devices.
> >
> > This SoC device has PCIe ethernet MAC attached to an integrated ethernet
> > switch using XGMII interface. The PCIe ethernet controller is presented to
> > the Linux host as PCI network device.
> >
> > The following block diagram gives an overview of the application.
> > +=================================+
> > | Host CPU/Linux |
> > +=================================+
> > || PCIe
> > ||
> > +==========================================+
> > | +--------------+ |
> > | | PCIE Endpoint| |
> > | | Ethernet | |
> > | | Controller | |
> > | | DMA | |
> > | +--------------+ |
> > | | MAC | BCM8958X |
> > | +--------------+ SoC |
> > | || XGMII |
> > | || |
> > | +--------------+ |
> > | | Ethernet | |
> > | | switch | |
> > | +--------------+ |
> > | || || || || |
> > +==========================================+
> > || || || || More external interfaces
> >
> > The MAC block on BCM8958x is based on Synopsis XGMAC 4.00a core. This
> > driver uses common dwxgmac2 code where applicable.
>
> Thanks for submitting the series.
>
> I am curious how come Broadcom got to use an IP-core which hasn't
> been even announced by Synopsys. AFAICS the most modern DW XGMAC
> IP-core is of v3.xxa version:
>
> https://www.synopsys.com/dw/ipdir.php?ds=dwc_ether_xgmac
>
I am not sure why the 4.00a IP-code is not announced for general
availability yet.
The Synopsis documentation for this IP mentions 3.xx IP as reference
for this design and lists
new features for 4.00a.
> Are you sure that your device isn't equipped with some another DW MAC
> IP-core, like DW 25G Ethernet MAC? (which BTW is equipped with a new
> Hyper DMA engine with a capability to have up to 128/256 channels with
> likely indirect addressing.) Do I miss something?
>
Yes, I briefly mentioned the new DMA architecture in the commit log
for patch 1/3.
You are correct, the name for the new DMA engine is Hyper DMA. It
probably started with some 3.xx IP-Core.
This DW-MAC is capable of 25G, but this SOC is not using 25G support.
> * I'll join the patch set review after the weekend, sometime on the
> next week.
>
> -Serge(y)
>
> > Driver functionality specific to this MAC is implemented in dwxgmac4.c.
> > Management of integrated ethernet switch on this SoC is not handled by
> > the PCIe interface.
> > This SoC device has PCIe ethernet MAC directly attached to an integrated
> > ethernet switch using XGMII interface.
> >
> > v2->v3:
> > Addressed v2 comments from Andrew, Jakub, Russel and Simon.
> > Based on suggestion by Russel and Andrew, added software node to create
> > phylink in fixed-link mode.
> > Moved dwxgmac4 specific functions to new files dwxgmac4.c and dwxgmac4.h
> > in stmmac core module.
> > Reorganized the code to use the existing glue logic support for xgmac in
> > hwif.c and override ops functions for dwxgmac4 specific functions.
> > The patch is split into three parts.
> > Patch#1 Adds dma_ops for dwxgmac4 in stmmac core
> > Patch#2 Hooks in the hardware interface handling for dwxgmac4
> > Patch#3 Adds PCI driver for BCM8958x device
> >
> > v1->v2:
> > Minor fixes to address coding style issues.
> > Sent v2 too soon by mistake, without waiting for review comments.
> > Received feedback on this version.
> > https://lore.kernel.org/netdev/20240511015924.41457-1-jitendra.vegiraju@broadcom.com/
> >
> > v1:
> > https://lore.kernel.org/netdev/20240510000331.154486-1-jitendra.vegiraju@broadcom.com/
> >
> > Jitendra Vegiraju (3):
> > Add basic dwxgmac4 support to stmmac core
> > Integrate dwxgmac4 into stmmac hwif handling
> > Add PCI driver support for BCM8958x
> >
> > MAINTAINERS | 8 +
> > drivers/net/ethernet/stmicro/stmmac/Kconfig | 11 +
> > drivers/net/ethernet/stmicro/stmmac/Makefile | 3 +-
> > drivers/net/ethernet/stmicro/stmmac/common.h | 4 +
> > .../net/ethernet/stmicro/stmmac/dwmac-brcm.c | 517 ++++++++++++++++++
> > .../ethernet/stmicro/stmmac/dwxgmac2_dma.c | 31 ++
> > .../net/ethernet/stmicro/stmmac/dwxgmac4.c | 142 +++++
> > .../net/ethernet/stmicro/stmmac/dwxgmac4.h | 84 +++
> > drivers/net/ethernet/stmicro/stmmac/hwif.c | 26 +-
> > drivers/net/ethernet/stmicro/stmmac/hwif.h | 1 +
> > 10 files changed, 825 insertions(+), 2 deletions(-)
> > create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwmac-brcm.c
> > create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwxgmac4.c
> > create mode 100644 drivers/net/ethernet/stmicro/stmmac/dwxgmac4.h
> >
> > --
> > 2.34.1
> >
> >
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