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=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 E607BC433E2 for ; Sat, 12 Sep 2020 23:01:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B4C8F20770 for ; Sat, 12 Sep 2020 23:01:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="cFYUUX8t" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725913AbgILXBw (ORCPT ); Sat, 12 Sep 2020 19:01:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725903AbgILXBt (ORCPT ); Sat, 12 Sep 2020 19:01:49 -0400 Received: from mail-ot1-x341.google.com (mail-ot1-x341.google.com [IPv6:2607:f8b0:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC8C7C061574 for ; Sat, 12 Sep 2020 16:01:48 -0700 (PDT) Received: by mail-ot1-x341.google.com with SMTP id n61so11519603ota.10 for ; Sat, 12 Sep 2020 16:01:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=0m6aJ6IVMUWWmvAiynENtbggnVCLW+2icfqjSBWtS5I=; b=cFYUUX8ttmtgUclcC895P9U9pk0bPL832aNTBKLfyu65yPGoW/i+vFTdQuDFhMfFfH 7O+tUdqA24+52JRHzHAECEXbIaBw3J/x0Hee5qeTDr95VOgkZcF2H6OG8Q6ZuVtQ/MVm QeuUUDNAj3RGIuVuzqcUFYWdiXr0b0opS4qowxRtyzaBSB1GK0Ghpp3efQw8wszjO4dD b/4wtXNy3raTll7T+QY3hReScmTXsmECKgobNwVG9BNvEyX/wotyUQUiGu7qj1AT1Ed4 +WSc3DJIq8MVp2QU3poXvUHg7y3QUzqhsOQUtZVozVJn6K8h9VCxEq5Fc1PsV7vZd/tC 6n5g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=0m6aJ6IVMUWWmvAiynENtbggnVCLW+2icfqjSBWtS5I=; b=idI4MrEwl+HfJfJ20haiNRz/n5GE0he6Q5QlMEUx3t5ObtRduk9bcdsOZDVx/gLGg1 Odnv0wWmd8eF5lkq812tLFTg1ok43GxcCseLkd7+BEx16OrNQR1esGeD/CqXy2Jf/2FU HxNdU7q3b/GH3XC9yuY71dT9kwGazk8Jf8m05Lr/geA5C6BO5jfVQqeVohuctRwnZMds S5xUMpbBTTMhxUnc3QRr1RjB4PMeFmg2/zW0ZRPniNdKbAZJR7DbN/zq8orJvGxK8L/L MSd8CDsyEK7IfUddktqtXA3chiSpcQuZZVyWgK3xBJa/slETo/gA2AWyJYwEQg+niD1L K3fg== X-Gm-Message-State: AOAM532fkTu4AwxDHT+tMLsvK+wv26CLFqGcYSJivxgJQYmqflQKHm0Q V6Ukok6bO9uLKVlIwn44D9MeCQ== X-Google-Smtp-Source: ABdhPJyBKUHUGYwT0cPFiyRRjTNn1lLbBfXouuQ4OCesRxxdK4vOmqUHjDeNe+gQF6t/HVtPvtqAEw== X-Received: by 2002:a9d:2925:: with SMTP id d34mr5133656otb.140.1599951707066; Sat, 12 Sep 2020 16:01:47 -0700 (PDT) Received: from yoga ([2605:6000:e5cb:c100:8898:14ff:fe6d:34e]) by smtp.gmail.com with ESMTPSA id 39sm1019630oto.67.2020.09.12.16.01.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Sep 2020 16:01:46 -0700 (PDT) Date: Sat, 12 Sep 2020 18:01:43 -0500 From: Bjorn Andersson To: Douglas Anderson Cc: Mark Brown , Akash Asthana , swboyd@chromium.org, Andy Gross , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Subject: Re: [PATCH 2/3] spi: spi-geni-qcom: Don't program CS_TOGGLE again and again Message-ID: <20200912230143.GC3715@yoga> References: <20200912140730.1.Ie67fa32009b94702d56232c064f1d89065ee8836@changeid> <20200912140730.2.I33e571179986850b4ec17042e813d0b08fb1b9c1@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200912140730.2.I33e571179986850b4ec17042e813d0b08fb1b9c1@changeid> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat 12 Sep 16:08 CDT 2020, Douglas Anderson wrote: > We always toggle the chip select manually in spi-geni-qcom so that we > can properly implement the Linux API. There's no reason to program > this to the hardware on every transfer. Program it once at init and > be done with it. > > This saves some part of a microsecond of overhead on each transfer. > While not really noticeable on any real world benchmarks, we might as > well save the time. > Reviewed-by: Bjorn Andersson Regards, Bjorn > Signed-off-by: Douglas Anderson > --- > > drivers/spi/spi-geni-qcom.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c > index 7f0bf0dec466..92d88bf85a90 100644 > --- a/drivers/spi/spi-geni-qcom.c > +++ b/drivers/spi/spi-geni-qcom.c > @@ -290,6 +290,7 @@ static int spi_geni_init(struct spi_geni_master *mas) > { > struct geni_se *se = &mas->se; > unsigned int proto, major, minor, ver; > + u32 spi_tx_cfg; > > pm_runtime_get_sync(mas->dev); > > @@ -322,6 +323,11 @@ static int spi_geni_init(struct spi_geni_master *mas) > > geni_se_select_mode(se, GENI_SE_FIFO); > > + /* We always control CS manually */ > + spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG); > + spi_tx_cfg &= ~CS_TOGGLE; > + writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG); > + > pm_runtime_put(mas->dev); > return 0; > } > @@ -331,7 +337,7 @@ static void setup_fifo_xfer(struct spi_transfer *xfer, > u16 mode, struct spi_master *spi) > { > u32 m_cmd = 0; > - u32 spi_tx_cfg, len; > + u32 len; > struct geni_se *se = &mas->se; > int ret; > > @@ -350,7 +356,6 @@ static void setup_fifo_xfer(struct spi_transfer *xfer, > spin_lock_irq(&mas->lock); > spin_unlock_irq(&mas->lock); > > - spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG); > if (xfer->bits_per_word != mas->cur_bits_per_word) { > spi_setup_word_len(mas, mode, xfer->bits_per_word); > mas->cur_bits_per_word = xfer->bits_per_word; > @@ -364,8 +369,6 @@ static void setup_fifo_xfer(struct spi_transfer *xfer, > mas->tx_rem_bytes = 0; > mas->rx_rem_bytes = 0; > > - spi_tx_cfg &= ~CS_TOGGLE; > - > if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) > len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word; > else > @@ -384,7 +387,6 @@ static void setup_fifo_xfer(struct spi_transfer *xfer, > writel(len, se->base + SE_SPI_RX_TRANS_LEN); > mas->rx_rem_bytes = xfer->len; > } > - writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG); > > /* > * Lock around right before we start the transfer since our > -- > 2.28.0.618.gf4bc123cb7-goog >