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Sun, 23 May 2021 19:34:59 -0700 (PDT) MIME-Version: 1.0 References: <20210519080436.18975-1-jamin_lin@aspeedtech.com> <20210519080436.18975-2-jamin_lin@aspeedtech.com> <20210520033140.GA3656@aspeedtech.com> <20210521020033.GB19153@taoren-ubuntu-R90MNF91> <20210524015310.GA2591@aspeedtech.com> In-Reply-To: <20210524015310.GA2591@aspeedtech.com> From: Joel Stanley Date: Mon, 24 May 2021 02:34:47 +0000 Message-ID: Subject: Re: [PATCH 1/3] i2c: aspeed: avoid new registers definition of AST2600 To: Jamin Lin Cc: Tao Ren , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "moderated list:ARM/ASPEED MACHINE SUPPORT" , "moderated list:ARM/ASPEED I2C DRIVER" , Brendan Higgins , open list , Rob Herring , Rayn Chen , "open list:I2C SUBSYSTEM HOST DRIVERS" , Steven Lee , "moderated list:ARM/ASPEED MACHINE SUPPORT" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210523_193502_361293_F97C75E3 X-CRM114-Status: GOOD ( 31.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 24 May 2021 at 01:53, Jamin Lin wrote: > > The 05/21/2021 02:00, Tao Ren wrote: > > Hi Jamin, > > > > On Thu, May 20, 2021 at 11:31:41AM +0800, Jamin Lin wrote: > > > The 05/19/2021 22:59, Joel Stanley wrote: > > > > On Wed, 19 May 2021 at 08:05, Jamin Lin wrote: > > > > > > > > > > The register definition between AST2600 A2 and A3 is different. > > > > > This patch avoid new registers definition of AST2600 to use > > > > > this driver. We will submit the path for the new registers > > > > > definition of AST2600. > > > > > > > > The AST2600 v9 datasheet says that bit 2 selects between old and new > > > > register sets, and that the old register set is the default. > > > > > > > > Has the default changed for the A3?, and the datasheet is incorrect? > > > > > > > > Does the A3 still support the old register set? > > > > > > > We suggest user to use the new i2c driver for AST2600 and we will sumbit > > > it. This driver is used to AST2500 and AST2400 SOCs. Change this > > > driver to check global register of i2c to avoid user build the wrong driver. > > > > If I understand correctly, the answer implies old register set is still > > supported in A3 although aspeed suggest people using the new driver/mode? > > > > Can you please share more context behind the suggestion? Such as new > > register mode has better performance? Or some known issues that were > > deteted in old mode are fixed in new register mode? > > > Yes, AST2600 A1, A2 and A3 support both old and new register set. The difference > between old and new register set are the register address and supported registers. > User can choose to use both old and new register set. However, ASPEED would like to > change new register set by default for AST2600. We can certainly make the driver for the new register set the default for AST2600 when the new driver is merged. I disagree that we should introduce a run time check to fail to probe the old driver. Please do not merge this patch. Please focus your effort on getting the new driver merged instead. Cheers, Joel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel