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Miller" , Alexandre Torgue , Jose Abreu , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Joao Pinto , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, xfr@outlook.com, rock.xu@nio.com Subject: Re: [PATCH net-next v1 1/7] net: stmmac: xgmac: drop incomplete FPE implementation Message-ID: <20240709171018.7tifdirqjhq6cohy@skbuf> References: Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Hi Andrew, Furong, On Tue, Jul 09, 2024 at 03:16:35PM +0200, Andrew Lunn wrote: > On Tue, Jul 09, 2024 at 04:21:19PM +0800, Furong Xu wrote: > > The FPE support for xgmac is incomplete, drop it temporarily. > > Once FPE implementation is refactored, xgmac support will be added. > > This is a pretty unusual thing to do. What does the current > implementation do? Is there enough for it to actually work? If i was > doing a git bisect and landed on this patch, could i find my > networking is broken? > > More normal is to build a new implementation by the side, and then > swap to it. > > Andrew > There were 2 earlier attempts from Jianheng Zhang @ Synopsys to add FPE support to new hardware. I told him that the #1 priority should be to move the stmmac driver over to the new standard API which uses ethtool + tc. https://lore.kernel.org/netdev/CY5PR12MB63726FED738099761A9B81E7BF8FA@CY5PR12MB6372.namprd12.prod.outlook.com/ https://lore.kernel.org/netdev/CY5PR12MB63727C24923AE855CFF0D425BF8EA@CY5PR12MB6372.namprd12.prod.outlook.com/ I'm not sure what happened in the meantime. Jianheng must have faced some issue, because he never came back. I did comment this at the time: | Even this very patch is slightly strange - it is not brand new hardware | support, but it fills in some more FPE ops in dwxlgmac2_ops - when | dwxgmac3_fpe_configure() was already there. So this suggests the | existing support was incomplete. How complete is it now? No way to tell. | There is a selftest to tell, but we can't run it because the driver | doesn't integrate with those kernel APIs. So it is relatively known that the support is incomplete. But I still think we should push for more reviewer insight into this driver by having access to a selftest to get a clearer picture of how it behaves. For that, we need the compliance to the common API. Otherwise, I completely agree to the idea that any development should be done incrementally on top of whatever already exists, instead of putting a curtain on and then taking it back off.