Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754699AbaKELkM (ORCPT ); Wed, 5 Nov 2014 06:40:12 -0500 Received: from mail-pd0-f178.google.com ([209.85.192.178]:49515 "EHLO mail-pd0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753644AbaKELkI (ORCPT ); Wed, 5 Nov 2014 06:40:08 -0500 Date: Wed, 5 Nov 2014 03:40:04 -0800 From: Brian Norris To: Huang Shijie Cc: Boris Brezillon , David Woodhouse , linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Mike Voytovich , Roy Lee Subject: Re: [PATCH v4 1/4] mtd: nand: provide detailed description for raw read/write page methods Message-ID: <20141105114004.GL22361@norris-Latitude-E6410> References: <1413794777-32220-1-git-send-email-boris.brezillon@free-electrons.com> <1413794777-32220-2-git-send-email-boris.brezillon@free-electrons.com> <20141025035524.GA3579@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20141025035524.GA3579@localhost.localdomain> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 25, 2014 at 11:55:27AM +0800, Huang Shijie wrote: > On Mon, Oct 20, 2014 at 10:46:14AM +0200, Boris Brezillon wrote: > > read_page_raw and write_page_raw method description is not clear enough. > > It clearly specifies that ECC correction should not be involved but does > > not talk about specific layout (by layout I mean where in-band and > > out-of-band data are stored on the NAND media) used by NAND/ECC > > controllers. > > > > Those specific layouts might impact MTD users and thus should be hidden (as > > already done in the standard NAND_ECC_HW_SYNDROME implementation). > > > > Clearly state this constraint in the nand_ecc_ctrl struct documentation. > > > > Signed-off-by: Boris Brezillon > > --- > > include/linux/mtd/nand.h | 17 +++++++++++++++-- > > 1 file changed, 15 insertions(+), 2 deletions(-) > > > > diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h > > index e4d451e..b14d190 100644 > > --- a/include/linux/mtd/nand.h > > +++ b/include/linux/mtd/nand.h > > @@ -455,8 +455,21 @@ struct nand_hw_control { > > * be provided if an hardware ECC is available > > * @calculate: function for ECC calculation or readback from ECC hardware > > * @correct: function for ECC correction, matching to ECC generator (sw/hw) > > - * @read_page_raw: function to read a raw page without ECC > > - * @write_page_raw: function to write a raw page without ECC > > + * @read_page_raw: function to read a raw page without ECC. This function > > + * should hide the specific layout used by the ECC > > + * controller and always return contiguous in-band and > > + * out-of-band data even if they're not stored > > + * contiguously on the NAND chip (e.g. > > + * NAND_ECC_HW_SYNDROME interleaves in-band and > > + * out-of-band data). > > + * @write_page_raw: function to write a raw page without ECC. This function > > + * should hide the specific layout used by the ECC > > + * controller and consider the passed data as contiguous > > + * in-band and out-of-band data. ECC controller is > > + * responsible for doing the appropriate transformations > > + * to adapt to its specific layout (e.g. > > + * NAND_ECC_HW_SYNDROME interleaves in-band and > > + * out-of-band data). > > * @read_page: function to read a page according to the ECC generator > > * requirements; returns maximum number of bitflips corrected in > > * any single ECC step, 0 if bitflips uncorrectable, -EIO hw error > > -- > > 1.9.1 > > > thanks for this patch. > > hi Brian, what's your opinion about this patch? I like the concept. It might be more succinctly described along the lines of "the same layout as the non-raw versions (i.e., .read_page / .write_page)". But the extra words may help for being more explicit. I haven't taken a closer look at the other patches yet. Brian -- 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/