From patchwork Tue Nov 8 12:56:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Biju Das X-Patchwork-Id: 13036249 X-Patchwork-Delegate: pavel@denx.de 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 aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id 070D4C43217 for ; Tue, 8 Nov 2022 12:56:50 +0000 (UTC) Received: from relmlie5.idc.renesas.com (relmlie5.idc.renesas.com [210.160.252.171]) by mx.groups.io with SMTP id smtpd.web10.7381.1667912195619553618 for ; Tue, 08 Nov 2022 04:56:39 -0800 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: bp.renesas.com, ip: 210.160.252.171, mailfrom: biju.das.jz@bp.renesas.com) X-IronPort-AV: E=Sophos;i="5.96,147,1665414000"; d="scan'208";a="139360138" Received: from unknown (HELO relmlir5.idc.renesas.com) ([10.200.68.151]) by relmlie5.idc.renesas.com with ESMTP; 08 Nov 2022 21:56:38 +0900 Received: from localhost.localdomain (unknown [10.226.92.61]) by relmlir5.idc.renesas.com (Postfix) with ESMTP id CE7474007204; Tue, 8 Nov 2022 21:56:36 +0900 (JST) From: Biju Das To: cip-dev@lists.cip-project.org, Nobuhiro Iwamatsu , Pavel Machek Cc: Chris Paterson , Biju Das Subject: [PATCH 5.10.y-cip 2/3] mmc: renesas_sdhi: Fix rounding errors Date: Tue, 8 Nov 2022 12:56:29 +0000 Message-Id: <20221108125630.3853219-3-biju.das.jz@bp.renesas.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221108125630.3853219-1-biju.das.jz@bp.renesas.com> References: <20221108125630.3853219-1-biju.das.jz@bp.renesas.com> MIME-Version: 1.0 List-Id: X-Webhook-Received: from li982-79.members.linode.com [45.33.32.79] by aws-us-west-2-korg-lkml-1.web.codeaurora.org with HTTPS for ; Tue, 08 Nov 2022 12:56:50 -0000 X-Groupsio-URL: https://lists.cip-project.org/g/cip-dev/message/9946 commit f0c00454bf78975925eccc9737faaa4d4951edbf upstream. Due to clk rounding errors on RZ/G2L platforms, it selects a clock source with a lower clock rate compared to a higher one. For eg: The rounding error (533333333 Hz / 4 * 4 = 533333332 Hz < 5333333 33 Hz) selects a clk source of 400 MHz instead of 533.333333 MHz. This patch fixes this issue by adding a margin of (1/1024) higher to the clock rate. Signed-off-by: Biju Das Reviewed-by: Geert Uytterhoeven Tested-by: Geert Uytterhoeven Reviewed-by: Wolfram Sang Tested-by: Wolfram Sang Fixes: bb6d3fa98a41 ("clk: renesas: rcar-gen3: Switch to new SD clock handling") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220928110755.849275-1-biju.das.jz@bp.renesas.com Signed-off-by: Ulf Hansson [biju: fixed the conflicts manually] Signed-off-by: Biju Das --- drivers/mmc/host/renesas_sdhi_core.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c index 120bb5860645..589e19ff52c6 100644 --- a/drivers/mmc/host/renesas_sdhi_core.c +++ b/drivers/mmc/host/renesas_sdhi_core.c @@ -128,6 +128,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host, { struct renesas_sdhi *priv = host_to_priv(host); unsigned int freq, diff, best_freq = 0, diff_min = ~0; + unsigned int new_upper_limit; int i; /* @@ -143,14 +144,21 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host, * greater than, new_clock. As we can divide by 1 << i for * any i in [0, 9] we want the input clock to be as close as * possible, but no greater than, new_clock << i. + * + * Add an upper limit of 1/1024 rate higher to the clock rate to fix + * clk rate jumping to lower rate due to rounding error (eg: RZ/G2L has + * 3 clk sources 533.333333 MHz, 400 MHz and 266.666666 MHz. The request + * for 533.333333 MHz will selects a slower 400 MHz due to rounding + * error (533333333 Hz / 4 * 4 = 533333332 Hz < 533333333 Hz)). */ for (i = min(9, ilog2(UINT_MAX / new_clock)); i >= 0; i--) { freq = clk_round_rate(priv->clk, new_clock << i); - if (freq > (new_clock << i)) { + new_upper_limit = (new_clock << i) + ((new_clock << i) >> 10); + if (freq > new_upper_limit) { /* Too fast; look for a slightly slower option */ freq = clk_round_rate(priv->clk, (new_clock << i) / 4 * 3); - if (freq > (new_clock << i)) + if (freq > new_upper_limit) continue; } @@ -169,6 +177,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host, static void renesas_sdhi_set_clock(struct tmio_mmc_host *host, unsigned int new_clock) { + unsigned int clk_margin; u32 clk = 0, clock; sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN & @@ -182,7 +191,13 @@ static void renesas_sdhi_set_clock(struct tmio_mmc_host *host, host->mmc->actual_clock = renesas_sdhi_clk_update(host, new_clock); clock = host->mmc->actual_clock / 512; - for (clk = 0x80000080; new_clock >= (clock << 1); clk >>= 1) + /* + * Add a margin of 1/1024 rate higher to the clock rate in order + * to avoid clk variable setting a value of 0 due to the margin + * provided for actual_clock in renesas_sdhi_clk_update(). + */ + clk_margin = new_clock >> 10; + for (clk = 0x80000080; new_clock + clk_margin >= (clock << 1); clk >>= 1) clock <<= 1; /* 1/1 clock is option */