From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.bootlin.com ([62.4.15.54]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1fft8b-0003KL-EM for linux-mtd@lists.infradead.org; Wed, 18 Jul 2018 20:33:32 +0000 From: Miquel Raynal To: Boris Brezillon , Richard Weinberger , David Woodhouse , Brian Norris , Marek Vasut Cc: linux-mtd@lists.infradead.org, Miquel Raynal Subject: [PATCH v2] mtd: adapt misleading comment in mtd_oob_ops structure Date: Wed, 18 Jul 2018 22:33:02 +0200 Message-Id: <20180718203302.5666-1-miquel.raynal@bootlin.com> List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , A comment in the kernel doc of the mtd_oob_ops structure tells that it is not possible to write more than one page with OOB. This is actually true for only a few MTD devices like 'onenand' but it is definitely not a general limitation. While this would benefit to be handled elsewhere either by the MTD layer or by the limited drivers, let's update this comment to reflect the reality. Signed-off-by: Miquel Raynal --- Changes since v1: ================= * Boris pointed out that this comment was not entirely false but rather too much restrictive compared to the reality and proposed an alternative that I simply copied there. include/linux/mtd/mtd.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index a86c4fa93115..cd0be91bdefa 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -67,9 +67,11 @@ struct mtd_erase_region_info { * @datbuf: data buffer - if NULL only oob data are read/written * @oobbuf: oob data buffer * - * Note, it is allowed to read more than one OOB area at one go, but not write. - * The interface assumes that the OOB write requests program only one page's - * OOB area. + * Note, some MTD drivers do not allow you to write more than one OOB area at + * one go. If you try to do that on such an MTD device, -EINVAL will be + * returned. If you want to make your implementation portable on all kind of MTD + * devices you should split the write request into several sub-requests when the + * request crosses a page boundary. */ struct mtd_oob_ops { unsigned int mode; -- 2.14.1