Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D6AEC433F5 for ; Fri, 19 Nov 2021 15:03:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4BEC361B27 for ; Fri, 19 Nov 2021 15:03:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232764AbhKSPGh (ORCPT ); Fri, 19 Nov 2021 10:06:37 -0500 Received: from relay5-d.mail.gandi.net ([217.70.183.197]:55323 "EHLO relay5-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233189AbhKSPGc (ORCPT ); Fri, 19 Nov 2021 10:06:32 -0500 Received: (Authenticated sender: herve.codina@bootlin.com) by relay5-d.mail.gandi.net (Postfix) with ESMTPA id 5C01F1C0017; Fri, 19 Nov 2021 15:03:29 +0000 (UTC) From: Herve Codina To: Miquel Raynal , Richard Weinberger , Vignesh Raghavendra Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, Herve Codina , Thomas Petazzoni Subject: [PATCH v3 4/4] mtd: rawnand: fsmc: Fix timing computation Date: Fri, 19 Nov 2021 16:03:16 +0100 Message-Id: <20211119150316.43080-5-herve.codina@bootlin.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211119150316.43080-1-herve.codina@bootlin.com> References: <20211119150316.43080-1-herve.codina@bootlin.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Under certain circumstances, the timing settings calculated by the FSMC NAND controller driver were inaccurate. These settings led to incorrect data reads or fallback to timing mode 0 depending on the NAND chip used. The timing computation did not take into account the following constraint given in SPEAr3xx reference manual: twait >= tCEA - (tset * TCLK) + TOUTDEL + TINDEL Enhance the timings calculation by taking into account this additional constraint. This change has no impact on slow timing modes such as mode 0. Indeed, on mode 0, computed values are the same with and without the patch. NANDs which previously stayed in mode 0 because of fallback to mode 0 can now work at higher speeds and NANDs which were not working at all because of the corrupted data work at high speeds without troubles. Overall improvement on a Micron/MT29F1G08 (flash_speed tool): mode0 mode3 eraseblock write speed 3220 KiB/s 4511 KiB/s eraseblock read speed 4491 KiB/s 7529 KiB/s Fixes: d9fb079571833 ("mtd: nand: fsmc: add support for SDR timings") Signed-off-by: Herve Codina --- Changes v1 to v2: - Commit log reword - Added performance details in commit log - Used #define for TOUTDEL and TINDEL and Fixed coding style - Used max3() Changes v2 -> v3: - Improved commit log - Added 'Fixes' reference - Changed comment in source code drivers/mtd/nand/raw/fsmc_nand.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-) diff --git a/drivers/mtd/nand/raw/fsmc_nand.c b/drivers/mtd/nand/raw/fsmc_nand.c index 0a6c9ef0ea8b..6b2bda815b88 100644 --- a/drivers/mtd/nand/raw/fsmc_nand.c +++ b/drivers/mtd/nand/raw/fsmc_nand.c @@ -94,6 +94,14 @@ #define FSMC_BUSY_WAIT_TIMEOUT (1 * HZ) +/* + * According to SPEAr300 Reference Manual (RM0082) + * TOUDEL = 7ns (Output delay from the flip-flops to the board) + * TINDEL = 5ns (Input delay from the board to the flipflop) + */ +#define TOUTDEL 7000 +#define TINDEL 5000 + struct fsmc_nand_timings { u8 tclr; u8 tar; @@ -278,7 +286,7 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host, { unsigned long hclk = clk_get_rate(host->clk); unsigned long hclkn = NSEC_PER_SEC / hclk; - u32 thiz, thold, twait, tset; + u32 thiz, thold, twait, tset, twait_min; if (sdrt->tRC_min < 30000) return -EOPNOTSUPP; @@ -310,13 +318,6 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host, else if (tims->thold > FSMC_THOLD_MASK) tims->thold = FSMC_THOLD_MASK; - twait = max(sdrt->tRP_min, sdrt->tWP_min); - tims->twait = DIV_ROUND_UP(twait / 1000, hclkn) - 1; - if (tims->twait == 0) - tims->twait = 1; - else if (tims->twait > FSMC_TWAIT_MASK) - tims->twait = FSMC_TWAIT_MASK; - tset = max(sdrt->tCS_min - sdrt->tWP_min, sdrt->tCEA_max - sdrt->tREA_max); tims->tset = DIV_ROUND_UP(tset / 1000, hclkn) - 1; @@ -325,6 +326,21 @@ static int fsmc_calc_timings(struct fsmc_nand_data *host, else if (tims->tset > FSMC_TSET_MASK) tims->tset = FSMC_TSET_MASK; + /* + * According to SPEAr300 Reference Manual (RM0082) which gives more + * information related to FSMSC timings than the SPEAr600 one (RM0305), + * twait >= tCEA - (tset * TCLK) + TOUTDEL + TINDEL + */ + twait_min = sdrt->tCEA_max - ((tims->tset + 1) * hclkn * 1000) + + TOUTDEL + TINDEL; + twait = max3(sdrt->tRP_min, sdrt->tWP_min, twait_min); + + tims->twait = DIV_ROUND_UP(twait / 1000, hclkn) - 1; + if (tims->twait == 0) + tims->twait = 1; + else if (tims->twait > FSMC_TWAIT_MASK) + tims->twait = FSMC_TWAIT_MASK; + return 0; } -- 2.31.1