From mboxrd@z Thu Jan 1 00:00:00 1970 From: boris.brezillon@bootlin.com (Boris Brezillon) Date: Fri, 20 Jul 2018 21:29:10 +0200 Subject: [RFC PATCH 3/8] mtd: rawnand: ams-delta: Set port direction once per transfer In-Reply-To: <90128326.sKM4evrj8F@z50> References: <20180718235710.18242-1-jmkrzyszt@gmail.com> <20180718235710.18242-4-jmkrzyszt@gmail.com> <20180719082318.290abee1@bbrezillon> <90128326.sKM4evrj8F@z50> Message-ID: <20180720212910.49bb2a88@bbrezillon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 20 Jul 2018 20:12:05 +0200 Janusz Krzysztofik wrote: > On Thursday, July 19, 2018 8:23:18 AM CEST Boris Brezillon wrote: > > On Thu, 19 Jul 2018 01:57:05 +0200 > > Janusz Krzysztofik wrote: > > > > > In its current shape, the driver sets data port direction before each > > > byte read/write operation, even during multi-byte transfers. Optimize > > > that by setting the port direction only on first byte of each transfer. > > > > Sounds like premature optimization for something you'll rework when > > fully switching to the GPIO consumer API to control the DATA bus. > > Indeed, this optimization was crucial for getting acceptable performance of > data transfers over GPIO. I'm only not sure if there is any action in > response to your comment expected on my side, e.g., did you want to say I > should modify the patch description, or change the order of patches? I'm just saying that, since you switch to a solution that goes through the GPIO framework to control the data bus, making sure the the pin direction change is done only once when reading/writing several bytes is something you can do after/when transitioning to the new approach. So yes, I suggest to re-order patches, except that this patch won't look the same at all if you move it after the "use the GPIO consumer API to control data bus" patch.