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 X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D0283C43215 for ; Tue, 19 Nov 2019 05:32:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A2CB821783 for ; Tue, 19 Nov 2019 05:32:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574141573; bh=0ygN0E9IlVH1H4ShoeoX+2esYHh+PfpGzBtEyMhLJ2s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=dY8fDW+UXib2Weo0qs48ofLR2HBVv6Kj4xMwviYDXPF2lHa9G9db/YbV3PtTqbub7 GQOFCEMBlVRYQUpJBZfe2JTZOgF2xnhsWSOHrwbtGLVhL0t3/l0/YrmY1t4mxk/7WN EhI+FacNULFkhXs0/ScbvlKFaixBw1GDmwn1PkKE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729457AbfKSFcw (ORCPT ); Tue, 19 Nov 2019 00:32:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:53202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728703AbfKSFcu (ORCPT ); Tue, 19 Nov 2019 00:32:50 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 619D621783; Tue, 19 Nov 2019 05:32:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1574141568; bh=0ygN0E9IlVH1H4ShoeoX+2esYHh+PfpGzBtEyMhLJ2s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zzmUmMZmx6FBpPHgz6okxTqu+qqP0jQYZrzdNrkrZtYSotWQ7p/sg97xsWUDcL8qc KncXDmiWKsgA3dlqL2Ddd+YmYdNUDAStL334lopSW1o60MMHEow4RR0l5PudcQ4xkV Np4/rHYP3rVmmoUaOfkxGx52RWDJXkKjvj7iKLiw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Douglas Anderson , Matthias Kaehlcke , Andy Gross , Sasha Levin Subject: [PATCH 4.19 205/422] soc: qcom: geni: geni_se_clk_freq_match() should always accept multiples Date: Tue, 19 Nov 2019 06:16:42 +0100 Message-Id: <20191119051411.870960041@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191119051400.261610025@linuxfoundation.org> References: <20191119051400.261610025@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Douglas Anderson [ Upstream commit 867d4aa7013fdee8b962cde1711f96c8dd86d926 ] The geni_se_clk_freq_match() has some strange semantics. Specifically it is defined with two modes: 1. It can find a clock that's an exact multiple of the requested rate 2. It can find a non-exact match but it can't handle multiples then ...but callers should always be able to handle a clock that is a multiple of the requested clock so mode #2 doesn't really make sense. Let's change the semantics so that the non-exact match can also accept multiples and then change the code to handle that. The only caller of this code is the unlanded SPI driver [1] which currently passes "exact = True", thus it should be safe to change the semantics in this way. ...and, in fact, the SPI driver should likely be modified to pass "exact = False" (with the new semantics) since that will allow it to work with SPI devices that request a clock rate that doesn't exactly match a rate we can make. [1] https://lkml.kernel.org/r/1535107336-2214-1-git-send-email-dkota@codeaurora.org Fixes: eddac5af0654 ("soc: qcom: Add GENI based QUP Wrapper driver") Signed-off-by: Douglas Anderson Reviewed-by: Matthias Kaehlcke Signed-off-by: Andy Gross Signed-off-by: Sasha Levin --- drivers/soc/qcom/qcom-geni-se.c | 37 ++++++++++++++++++++------------- 1 file changed, 22 insertions(+), 15 deletions(-) diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c index 1b19b8428c4ac..ee89ffb6dde84 100644 --- a/drivers/soc/qcom/qcom-geni-se.c +++ b/drivers/soc/qcom/qcom-geni-se.c @@ -544,16 +544,17 @@ EXPORT_SYMBOL(geni_se_clk_tbl_get); * @se: Pointer to the concerned serial engine. * @req_freq: Requested clock frequency. * @index: Index of the resultant frequency in the table. - * @res_freq: Resultant frequency which matches or is closer to the - * requested frequency. + * @res_freq: Resultant frequency of the source clock. * @exact: Flag to indicate exact multiple requirement of the requested * frequency. * - * This function is called by the protocol drivers to determine the matching - * or exact multiple of the requested frequency, as provided by the serial - * engine clock in order to meet the performance requirements. If there is - * no matching or exact multiple of the requested frequency found, then it - * selects the closest floor frequency, if exact flag is not set. + * This function is called by the protocol drivers to determine the best match + * of the requested frequency as provided by the serial engine clock in order + * to meet the performance requirements. + * + * If we return success: + * - if @exact is true then @res_freq / == @req_freq + * - if @exact is false then @res_freq / <= @req_freq * * Return: 0 on success, standard Linux error codes on failure. */ @@ -564,6 +565,9 @@ int geni_se_clk_freq_match(struct geni_se *se, unsigned long req_freq, unsigned long *tbl; int num_clk_levels; int i; + unsigned long best_delta; + unsigned long new_delta; + unsigned int divider; num_clk_levels = geni_se_clk_tbl_get(se, &tbl); if (num_clk_levels < 0) @@ -572,18 +576,21 @@ int geni_se_clk_freq_match(struct geni_se *se, unsigned long req_freq, if (num_clk_levels == 0) return -EINVAL; - *res_freq = 0; + best_delta = ULONG_MAX; for (i = 0; i < num_clk_levels; i++) { - if (!(tbl[i] % req_freq)) { + divider = DIV_ROUND_UP(tbl[i], req_freq); + new_delta = req_freq - tbl[i] / divider; + if (new_delta < best_delta) { + /* We have a new best! */ *index = i; *res_freq = tbl[i]; - return 0; - } - if (!(*res_freq) || ((tbl[i] > *res_freq) && - (tbl[i] < req_freq))) { - *index = i; - *res_freq = tbl[i]; + /* If the new best is exact then we're done */ + if (new_delta == 0) + return 0; + + /* Record how close we got */ + best_delta = new_delta; } } -- 2.20.1