Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031289AbbDWXV1 (ORCPT ); Thu, 23 Apr 2015 19:21:27 -0400 Received: from mail1.bemta7.messagelabs.com ([216.82.254.106]:6240 "EHLO mail1.bemta7.messagelabs.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031011AbbDWXVY convert rfc822-to-8bit (ORCPT ); Thu, 23 Apr 2015 19:21:24 -0400 X-Greylist: delayed 416 seconds by postgrey-1.27 at vger.kernel.org; Thu, 23 Apr 2015 19:21:24 EDT X-Env-Sender: Iwo.Mergler@netcommwireless.com X-Msg-Ref: server-4.tower-171.messagelabs.com!1429830861!29380649!1 X-Originating-IP: [220.233.131.78] X-StarScan-Received: X-StarScan-Version: 6.13.6; banners=-,-,- X-VirusChecked: Checked From: Iwo Mergler To: Richard Weinberger , Josh Cartwright CC: Ben Shelton , "dwmw2@infradead.org" , "computersforpeace@gmail.com" , "dedekind1@gmail.com" , "adrian.hunter@intel.com" , "linux-mtd@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "punnaiah.choudary.kalluri@xilinx.com" , "xander.huff@ni.com" Date: Fri, 24 Apr 2015 09:13:24 +1000 Subject: RE: Adding subpage support to NAND driver -- backwards compatibility concerns Thread-Topic: Adding subpage support to NAND driver -- backwards compatibility concerns Thread-Index: AdB9/At1hqctXGAoQp+ILy7tLqIYpgAHw1rK Message-ID: References: <20150422172944.GA4134@bshelton-desktop> <20150423183957.GR27115@jcartwri.amer.corp.natinst.com>,<5539486F.60407@nod.at> In-Reply-To: <5539486F.60407@nod.at> Accept-Language: en-US, en-AU Content-Language: en-AU X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US, en-AU Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1323 Lines: 35 On Fri, 24 Apr 2015 05:30:55 +1000 Richard Weinberger wrote: > Am 23.04.2015 um 20:39 schrieb Josh Cartwright: > > Is there no metadata in the UBI data structures in flash that > > indicate the min IO boundary? Assuming no, is another option to, > > at the time of attach, try both the min IO access size, and, if > > that doesn't work, try the page size? > > Correct. UBI has no information about that. > If you add subpage support to the driver I'd make it opt-in such that > existing setups won't break. I'm wondering, given that EC headers contain vid header offset and data offset fields, shouldn't UBI be able to deduce at attach time what the relevant parameters are on a partition? Something along the lines of using the parameters of the first PEB with valid EC header, then balking if another EC header is encountered with different info. As long as MTD allows the so deduced minimum access size, it seems safe. This could help enormously in situations like this, where MTD drivers experience sudden bursts of improvement. Best regards, Iwo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/