From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1A951C433F5 for ; Thu, 14 Apr 2022 10:58:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=pEQlNNB9nCH2wUgcFqGtELQ+88cY+HxE8Q0lZQYIhY4=; b=JBZQa2wH2pTSFN ycxMJ4qvDtYfSKu2NfRXQOWcliX6UfsBiTr0YsPXYCfSF6wi8oKGbKcVnssyIB9lc6kJTWaAy7n+D 0zbn92fnY+s/NZBm4Hd3/T+Oo77jujHT5XdWFH508/sDg5y9HGLWgNAfFdWpc/gicWS+lAlTJay81 B1hOoGLmgz8nGkLhlUJrj6KhN9mSOtIrokT4RfFhpeWImlpARwo2hPdC6/lTnvZqgPqRrpDesGkAX eu20zZA9vdlGFY+Xmjx6ghh72J4OCnCNnXeC8xCK8UGX6Gweid3Yp4pFMoj9OHMU0jXyeLqzhWdzq wdlRkSGN/rOFT4/ZrhDw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nex9x-005Dlr-4A; Thu, 14 Apr 2022 10:57:09 +0000 Received: from smtp-out2.suse.de ([195.135.220.29]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nex9u-005Djr-0v; Thu, 14 Apr 2022 10:57:07 +0000 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id A59F21F746; Thu, 14 Apr 2022 10:56:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1649933816; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qHwXlFiPhb+8uq3WbY4A9X/xnSchmkHO2lazKJa/1C0=; b=xTC5BJvI3EIrrso3wUf3g1Nr7SOacNh0j7iO37GlzhLh9dS93gEQUQ7+pC7UTv3Yxp9HHo 7a95Me/ooKHX3mLKAkBbwlwnRM4Z11xTG3FPMqFZy85xh1nplyN07tFTpohWc1Q3zZHx3G SZ6KliHB8WrlgfICPUQ5iTNTJ5bMMH8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1649933816; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=qHwXlFiPhb+8uq3WbY4A9X/xnSchmkHO2lazKJa/1C0=; b=HSr8JiCOgkenIg7wB2Xon9FwkRKUvHaA6puuu4B3JMM3Ug4KlPFkmiOeosnWoqQEzSxbJN ziYtJKRIz8IMNDDw== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 8533E132C0; Thu, 14 Apr 2022 10:56:56 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id NbhsIPj9V2JxCQAAMHmgww (envelope-from ); Thu, 14 Apr 2022 10:56:56 +0000 Date: Thu, 14 Apr 2022 13:56:56 +0300 From: "Ivan T. Ivanov" To: Stefan Wahren Cc: Michael Turquette , Stephen Boyd , Nicolas Saenz Julienne , Florian Fainelli , Ray Jui , Scott Branden , Paul Walmsley , Palmer Dabbelt , Albert Ou , Phil Elwell , kernel test robot , bcm-kernel-feedback-list@broadcom.com, linux-clk@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org Subject: Re: [PATCH v2] clk: bcm2835: Round UART input clock up Message-ID: <20220414105656.qt52zmr5vjmjdcxc@suse> References: <20220404125113.80239-1-iivanov@suse.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220404125113.80239-1-iivanov@suse.de> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220414_035706_237354_09B08F2B X-CRM114-Status: GOOD ( 26.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Stefan, Please, could you take a look into following patch? Thanks! Ivan On 04-04 15:51, Ivan T. Ivanov wrote: > Subject: [PATCH v2] clk: bcm2835: Round UART input clock up > Message-Id: <20220404125113.80239-1-iivanov@suse.de> > > The UART clock is initialised to be as close to the requested > frequency as possible without exceeding it. Now that there is a > clock manager that returns the actual frequencies, an expected > 48MHz clock is reported as 47999625. If the requested baudrate > == requested clock/16, there is no headroom and the slight > reduction in actual clock rate results in failure. > > If increasing a clock by less than 0.1% changes it from ..999.. > to ..000.., round it up. > > This is reworked version of a downstream fix: > https://github.com/raspberrypi/linux/commit/ab3f1b39537f6d3825b8873006fbe2fc5ff057b7 > > Cc: Phil Elwell > Signed-off-by: Ivan T. Ivanov > --- > Changes since v1 > Make bcm2835_clock_round() static to fix following warning > when compiling for riscv: > drivers/clk/bcm/clk-bcm2835.c:997:15: warning: no previous prototype for 'bcm2835_clock_round' [-Wmissing-prototypes] > Reported-by: kernel test robot > > drivers/clk/bcm/clk-bcm2835.c | 30 ++++++++++++++++++++++++++++-- > 1 file changed, 28 insertions(+), 2 deletions(-) > > diff --git a/drivers/clk/bcm/clk-bcm2835.c b/drivers/clk/bcm/clk-bcm2835.c > index 3ad20e75fd23..c29b643d1bf5 100644 > --- a/drivers/clk/bcm/clk-bcm2835.c > +++ b/drivers/clk/bcm/clk-bcm2835.c > @@ -502,6 +502,8 @@ struct bcm2835_clock_data { > bool low_jitter; > > u32 tcnt_mux; > + > + bool round_up; > }; > > struct bcm2835_gate_data { > @@ -992,12 +994,30 @@ static long bcm2835_clock_rate_from_divisor(struct bcm2835_clock *clock, > return temp; > } > > +static unsigned long bcm2835_clock_round(unsigned long clk) > +{ > + unsigned long scaler; > + > + /* > + * If increasing a clock by less than 0.1% changes it > + * from ..999.. to ..000.., round up. > + */ > + scaler = 1; > + while (scaler * 100000 < clk) > + scaler *= 10; > + if ((clk + scaler - 1) / scaler % 1000 == 0) > + clk = (clk / scaler + 1) * scaler; > + > + return clk; > +} > + > static unsigned long bcm2835_clock_get_rate(struct clk_hw *hw, > unsigned long parent_rate) > { > struct bcm2835_clock *clock = bcm2835_clock_from_hw(hw); > struct bcm2835_cprman *cprman = clock->cprman; > const struct bcm2835_clock_data *data = clock->data; > + unsigned long rate; > u32 div; > > if (data->int_bits == 0 && data->frac_bits == 0) > @@ -1005,7 +1025,12 @@ static unsigned long bcm2835_clock_get_rate(struct clk_hw *hw, > > div = cprman_read(cprman, data->div_reg); > > - return bcm2835_clock_rate_from_divisor(clock, parent_rate, div); > + rate = bcm2835_clock_rate_from_divisor(clock, parent_rate, div); > + > + if (data->round_up) > + rate = bcm2835_clock_round(rate); > + > + return rate; > } > > static void bcm2835_clock_wait_busy(struct bcm2835_clock *clock) > @@ -2142,7 +2167,8 @@ static const struct bcm2835_clk_desc clk_desc_array[] = { > .div_reg = CM_UARTDIV, > .int_bits = 10, > .frac_bits = 12, > - .tcnt_mux = 28), > + .tcnt_mux = 28, > + .round_up = true), > > /* TV encoder clock. Only operating frequency is 108Mhz. */ > [BCM2835_CLOCK_VEC] = REGISTER_PER_CLK( > -- > 2.26.2 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel