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 B77FEC2D0E0 for ; Sat, 12 Sep 2020 22:53:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61B1421531 for ; Sat, 12 Sep 2020 22:53:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="IIBV5CQW" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725908AbgILWxM (ORCPT ); Sat, 12 Sep 2020 18:53:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725904AbgILWxJ (ORCPT ); Sat, 12 Sep 2020 18:53:09 -0400 Received: from mail-oi1-x241.google.com (mail-oi1-x241.google.com [IPv6:2607:f8b0:4864:20::241]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EA5EC061757 for ; Sat, 12 Sep 2020 15:53:09 -0700 (PDT) Received: by mail-oi1-x241.google.com with SMTP id w16so13509716oia.2 for ; Sat, 12 Sep 2020 15:53:09 -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=cz7l4bGKHxfOKLLWHxTc5xdJem1sy7MolpQaLjxPyvs=; b=IIBV5CQWWCEP4EhPOxuW3YsT6AjNbySc01Z76A7uG2S5Jzq2vxIBtlFKOh3c2PVluN 6Q+8a8JxTNnLL1pAtN5w+bcInwxcSBKcxQ8oj/OLTJuJ33vqYS8ApCil3XyXgRaUx1Fy 3WulOIghHJJWVtNcOFFrv3sc1o+anGkVrFXKMBrWA4mKKpnmItDpFOeY/KRjJ+T2tG5X 8muMim8x7c1YuF8u/MszgIIoKoW7Ln1/A8F2CNBlD9xTHWPpRERb/CT5ipz8pMKoE0Ku 2ORt0iLHrXk0JqyNfcIG9vc2ILu++sS0LkrerBC0v4i5k8QCCzGBV/Jqt1zeuDpaPZi8 CpLw== 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=cz7l4bGKHxfOKLLWHxTc5xdJem1sy7MolpQaLjxPyvs=; b=kWDHymwCakggOgPrDFXb3ZicPE7lTduqmkv6lQhTTh6/tMO6sQ3DPOKVkBb9VBt9GB bb9upKG//1GtOwARoYNXiN/lH3q+ExEkUlRF9BecrOAubiD8+TSj4yiY3UI06TZ4tHtH A8JGFum5fLEwe2zsZy99e0iIP4PUgSx7MJcfM6mFA0VE7HArjjebvkyAa/7X06N/uY8N gWTvaK4IvLB+ivt7ryIpJECc2dadztcZeBo68O0ANkL/jxrAKu84LiylpwLlxk9mgAjy tqbDRFB/mgrcvdcRHGGGW9sRHy7EqmJHd+C5jKmPQH+UK54akzXgO9siBy3nEbLLaM8k 2xtA== X-Gm-Message-State: AOAM533thtNfa8AHwD49N4f+gBlI3XYkfxHfhSAvHyUAyJ+LKCIYcuHo j9Lz6KvOPrK0s8WrfZ0SkD4C3w== X-Google-Smtp-Source: ABdhPJzz+WfOASs3fCTMejIUiZxcNkVCEBQZAPhC2t4wyDdxudf/q6ZNd/UCcJKeUAn8xAUTMyZuuw== X-Received: by 2002:aca:c5cd:: with SMTP id v196mr5077895oif.63.1599951186236; Sat, 12 Sep 2020 15:53:06 -0700 (PDT) Received: from yoga ([2605:6000:e5cb:c100:8898:14ff:fe6d:34e]) by smtp.gmail.com with ESMTPSA id l5sm1027934otj.40.2020.09.12.15.53.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 12 Sep 2020 15:53:05 -0700 (PDT) Date: Sat, 12 Sep 2020 17:53:02 -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 1/3] spi: spi-geni-qcom: Use the FIFO even more Message-ID: <20200912225302.GA3715@yoga> References: <20200912140730.1.Ie67fa32009b94702d56232c064f1d89065ee8836@changeid> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200912140730.1.Ie67fa32009b94702d56232c064f1d89065ee8836@changeid> Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Sat 12 Sep 16:07 CDT 2020, Douglas Anderson wrote: > In commit 902481a78ee4 ("spi: spi-geni-qcom: Actually use our FIFO") I > explained that the maximum size we could program the FIFO was > "mas->tx_fifo_depth - 3" but that I chose "mas->tx_fifo_depth()" > because I was worried about decreased bandwidth. > > Since that time: > * All the interconnect patches have landed, making things run at the > proper speed. > * I've done more measurements. > > This lets me confirm that there's really no downside of using the FIFO > more. Specifically I did "flashrom -p ec -r /tmp/foo.bin" on a > Chromebook and averaged over several runs. Wouldn't there be a downside in the form of setting the watermark that close to the full FIFO we have less room for being late handling the interrupt? Or is there some mechanism involved that will prevent the FIFO from being overrun? Regards, Bjorn > > Before: It took 6.66 seconds and 59669 interrupts fired. > After: It took 6.66 seconds and 47992 interrupts fired. > > Signed-off-by: Douglas Anderson > --- > > drivers/spi/spi-geni-qcom.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c > index 0dc3f4c55b0b..7f0bf0dec466 100644 > --- a/drivers/spi/spi-geni-qcom.c > +++ b/drivers/spi/spi-geni-qcom.c > @@ -308,7 +308,7 @@ static int spi_geni_init(struct spi_geni_master *mas) > * Hardware programming guide suggests to configure > * RX FIFO RFR level to fifo_depth-2. > */ > - geni_se_init(se, mas->tx_fifo_depth / 2, mas->tx_fifo_depth - 2); > + geni_se_init(se, mas->tx_fifo_depth - 3, mas->tx_fifo_depth - 2); > /* Transmit an entire FIFO worth of data per IRQ */ > mas->tx_wm = 1; > ver = geni_se_get_qup_hw_version(se); > -- > 2.28.0.618.gf4bc123cb7-goog >