From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751832AbdJEHX6 (ORCPT ); Thu, 5 Oct 2017 03:23:58 -0400 Received: from mail.free-electrons.com ([62.4.15.54]:33853 "EHLO mail.free-electrons.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751317AbdJEHX4 (ORCPT ); Thu, 5 Oct 2017 03:23:56 -0400 Date: Thu, 5 Oct 2017 09:23:54 +0200 From: Boris Brezillon To: Masahiro Yamada Cc: linux-mtd@lists.infradead.org, Cyrille Pitchen , linux-kernel@vger.kernel.org, Marek Vasut , Brian Norris , Richard Weinberger , David Woodhouse Subject: Re: [PATCH v3] mtd: nand: denali: fix setup_data_interface to meet tCCS delay Message-ID: <20171005092354.302ddb98@bbrezillon> In-Reply-To: <1506694377-8531-1-git-send-email-yamada.masahiro@socionext.com> References: <1506694377-8531-1-git-send-email-yamada.masahiro@socionext.com> X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Sep 2017 23:12:57 +0900 Masahiro Yamada wrote: > The WE_2_RE register specifies the number of clock cycles inserted > between the rising edge of #WE and the falling edge of #RE. > > The current setup_data_interface implementation takes care of tWHR, > but tCCS is missing. Wait for max(tCSS, tWHR) to meet the spec. > > With setup_data_interface() properly programmed, the Denali NAND > controller can observe the timing, so NAND_WAIT_TCCS flag is unneeded. > Clarify this in the comment block. Applied. Thanks, Boris > > Signed-off-by: Masahiro Yamada > --- > > Changes in v3: > - Remove comment abount NAND_WAIT_TWHR because 1/2 seems NACK > > Changes in v2: > - newly added > > drivers/mtd/nand/denali.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c > index 0b268ec..5124f8a 100644 > --- a/drivers/mtd/nand/denali.c > +++ b/drivers/mtd/nand/denali.c > @@ -1004,8 +1004,14 @@ static int denali_setup_data_interface(struct mtd_info *mtd, int chipnr, > tmp |= FIELD_PREP(RE_2_RE__VALUE, re_2_re); > iowrite32(tmp, denali->reg + RE_2_RE); > > - /* tWHR -> WE_2_RE */ > - we_2_re = DIV_ROUND_UP(timings->tWHR_min, t_clk); > + /* > + * tCCS, tWHR -> WE_2_RE > + * > + * With WE_2_RE properly set, the Denali controller automatically takes > + * care of the delay; the driver need not set NAND_WAIT_TCCS. > + */ > + we_2_re = DIV_ROUND_UP(max(timings->tCCS_min, timings->tWHR_min), > + t_clk); > we_2_re = min_t(int, we_2_re, TWHR2_AND_WE_2_RE__WE_2_RE); > > tmp = ioread32(denali->reg + TWHR2_AND_WE_2_RE);