From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH v3] mtd: atmel_nand: make PMECC lookup table and offset property optional Date: Thu, 16 Oct 2014 14:39:47 +0100 Message-ID: <20141016133947.GB24714@leverpostej> References: <1413021710-32264-1-git-send-email-josh.wu@atmel.com> <20141013111611.GC15326@leverpostej> <543BB7FE.3030604@atmel.com> <543CFC41.2060506@atmel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <543CFC41.2060506-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org> Content-Language: en-US Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Josh Wu Cc: "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Pawel Moll , "ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org" , "nicolas.ferre-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org" , "robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org" , "linux-mtd-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "voice.shen-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org" , "galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org" , "computersforpeace-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org" List-Id: devicetree@vger.kernel.org [...] > >> That said, if we can build this dynamically, can't we always do so, and > >> never need this property? > > > > Since board like at91sam9x5, sama5d3xek has a rom lookup table. And > > the sama5d4ek has no rom lookup table. > > To present this, I make this property as optional. > > > > But yes, the pmecc lookup table related properties can be removed as > > driver can build it in runtime. > > The cost is we need to use more memory to store the table. > > In precisely, the table need to 32k bytes memory for 512-sector, and 64k > bytes for 1024-sector. > > Also I spend time to testing the performance of this version. > Compare with the version which use the SRAM rom lookup table, this > version (build table in runtim) cost about 5~10ms more. > > So I prefer to keep this property as optional. Sure. It sounds like it's always possible to ignore it later if we choose to. I just wouldn't mention what the driver should do in the binding -- whether or not the property is optional, the behaviour of the driver is not a detail of the device. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html