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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Arun Ramadoss , Jiri Pirko , Linus Walleij , Florian Fainelli , Vivien Didelot , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de, Jens Emil Schulz =?iso-8859-1?Q?=D8stergaard?= Subject: Re: [PATCH net-next v2 1/3] net: dsa: microchip: ksz9477: apply a shorter ageing time at once Message-ID: <8a5d8502-3c38-4161-9b1d-381ef6e2344c@lunn.ch> References: <20261115-ksz-stp-ageing-v2-0-7af27320033e@pengutronix.de> <20261115-ksz-stp-ageing-v2-1-7af27320033e@pengutronix.de> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261115-ksz-stp-ageing-v2-1-7af27320033e@pengutronix.de> On Sun, Nov 15, 2026 at 11:59:51AM +0100, Oleksij Rempel wrote: > Pulse Fast Aging when the programmed ageing time gets shorter or the Age > Count gets smaller. > > The ageing time is Age Count times Age Period. An entry stores the Age > Count when it is updated, as the datasheet says. The datasheet does not > say when a new Age Period applies. > > Without the pulse, stale entries outlived an STP topology change. In my > STP tests the switch ran at 300 s as 4 x 75 s, its reset value. With > forward_delay 4 s, the bridge asks for an ageing time of 8 s. Read back > right after the write, the register showed 8 s. In three tests, an > entry learned before the change still stayed for more than a minute. I > think the switch uses the new Age Period only after the running one > ends. > > The pulse is also needed when the ageing time grows but the Age Count > shrinks. From 8 s (4 x 2 s) to 31 s (1 x 31 s), an entry stayed about > 63 s in one test. > > On a KSZ9893 the pulse removed the dynamic entries on the one user port > I tested. The new period then started right away. > > I found this in STP tests on a KSZ9893. I tested the fix there with > kernel STP and with STP off. With mstpd I checked only the programmed > ageing time, not the FDB. > > Fixes: 2c119d9982b1 ("net: dsa: microchip: add the support for set_ageing_time") > Signed-off-by: Oleksij Rempel Reviewed-by: Andrew Lunn Andrew