Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753414AbbEAHF7 (ORCPT ); Fri, 1 May 2015 03:05:59 -0400 Received: from mail-wg0-f49.google.com ([74.125.82.49]:36268 "EHLO mail-wg0-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752685AbbEAHF5 (ORCPT ); Fri, 1 May 2015 03:05:57 -0400 MIME-Version: 1.0 In-Reply-To: <201505010113.50293.marex@denx.de> References: <35add8df33b17e2354d9496eba8597d9d8488f30.1430430153.git.hramrach@gmail.com> <201505010113.50293.marex@denx.de> From: Michal Suchanek Date: Fri, 1 May 2015 09:05:15 +0200 Message-ID: Subject: Re: [PATCH 3/3] MTD: spi-nor: add flag to not use sector erase. To: Marek Vasut Cc: David Woodhouse , Brian Norris , "Rafa?? Mi??ecki" , Alison Chaiken , Ben Hutchings , Geert Uytterhoeven , "Bean Huo (beanhuo)" , "grmoore@altera.com" , linux-mtd@lists.infradead.org, Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1333 Lines: 36 On 1 May 2015 at 01:13, Marek Vasut wrote: > On Thursday, April 30, 2015 at 11:13:12 PM, Michal Suchanek wrote: >> The sector size of the flash memory is unclear from datasheet or may >> possibly vary between chips so add a flag to always use 4k blocks. >> >> Currently 4k blocks are always used when possible but in the future >> somebody might want to do some optimizations with sector erase. >> >> Signed-off-by: Michal Suchanek > > I _think_ you might be able to determine the size, no ? > > One way is to ask the vendor, but you can also try something like: > 1) erase the whole SPI NOR > 2) overwrite it with zeroes (or ones ? I think it should be all ones after > erasing). > 3) Erase sector 0 > 4) Read some 128 KiB back > 5) Observe what is the difference. > I can determine it for this particular chip. However, when the vendor datasheet says the block is 64/32K it might mean that chips with this ID can have either block size. It's a value that we don't use anyway so I just mark it as unknown here for future reference. Thanks Michal -- 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/