Re: [PATCH net-next v4 RESEND] stmmac: tegra: Add MGBE support

From: Jon Hunter <jonathanh@nvidia.com>
To: Bhadram Varka <vbhadram@nvidia.com>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Russell King <linux@armlinux.org.uk>,
	Andrew Lunn <andrew@lunn.ch>, Vladimir Oltean <olteanv@gmail.com>,
	Revanth Kumar Uppala <ruppala@nvidia.com>
Cc: "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH net-next v4 RESEND] stmmac: tegra: Add MGBE support
Date: Fri, 18 Nov 2022 09:23:06 +0000	[thread overview]
Message-ID: <fb2d6c81-7c89-dd8f-5e95-b4f5dd654c42@nvidia.com> (raw)
In-Reply-To: <LV2PR12MB5727354F4A1EDE7B08FBC5A5AF229@LV2PR12MB5727.namprd12.prod.outlook.com>

Hi Florian,

On 12/10/2022 05:56, Bhadram Varka wrote:

...

>> You should be modeling this as a proper PCS driver and have a 'pcs-handle'
>> property pointing to it in your Device Tree.
>>
>> The configuration you are doing here is probably working the first time you
>> bring-up the network device but I doubt it works across system
>> suspend/resume states where power to the GMAC and PCS is lost, it also
>> begs the question of which mediums this was tested with and whether
>> dynamic switching of speeds and so on is working?
>> --
> 
> For Tegra234, there is UPHY lanes control logic inside XPCS IP which is memory-mapped IP (not part of the MAC IP).
> mgbe_uphy_lane_bringup performs UPHY lane bring up here. Here MGBE/XPCS works in XFI mode.
> 
> Agree that lane bring down logic is not present interface down/suspend paths. Will update the changes accordingly.
> One more thing is that UPHY lane bring should happen only after the line side link is up. This also will make the changes.
> Please let me know if I miss anything here.

An updated version of this has now been posted [0]. It should have been 
marked as 'V5'. We have tested suspend/resume and verified that it is 
working. We are hoping to get this into Linux v6.2 if not too late. Let 
me know if you have any concerns.

Thanks
Jon

[0] 
https://lore.kernel.org/linux-tegra/20221118075744.49442-1-ruppala@nvidia.com/T/#t

-- 
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