From patchwork Thu Jun 25 00:08:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Douglas Anderson X-Patchwork-Id: 11624539 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B62C2138C for ; Thu, 25 Jun 2020 00:08:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8FA7E206DD for ; Thu, 25 Jun 2020 00:08:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="jOTatsuv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388058AbgFYAIP (ORCPT ); Wed, 24 Jun 2020 20:08:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55662 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387828AbgFYAIO (ORCPT ); Wed, 24 Jun 2020 20:08:14 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 209CBC061573 for ; Wed, 24 Jun 2020 17:08:14 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id k1so1915240pls.2 for ; Wed, 24 Jun 2020 17:08:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=cDQmr4M7f0b4vct3QfFl9IqKo/J7WcBaHfYFiG0iFP4=; b=jOTatsuvSAFGuC1zfOvuK87RmUepW0cCS/gKGHr6z7GtyB/DNCfzkpjiv0eSlqkgL7 4W0gMsAciQDh2x2Q/um5d43SuKEDH5Ob15/3R7ktlgpz4GsoUjf32Cv3X6u2JHbwHrPn jJ8YOn8/Bsk/1M+Z7fDSUlWLidg9db+SwOZaM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=cDQmr4M7f0b4vct3QfFl9IqKo/J7WcBaHfYFiG0iFP4=; b=cNAGOyS63KZcbUdSf6nSS1VujxZ1Gl8C34J1Y6KJszRcmp8G4oQ5Q3MFWiNVA3aADy RAyQpeuexLu1+Awl5TsYR0a7JUECZ/B8eONctXmPLO8fB3BhsXHfSwlNW/0LHtrl4RtX PA+t3AwU4D/DZvauSpnCLPLbFWoBSX6ciDkICicYc1u6opgbr9PgMWBjr1gXBfoKM9Tc kQ5m0yp08AeIS4j//FomjtcNgWjYcLVmXHTMETZrWKq7rtZBFUgeCWjdDHLDivSacnNP KH14tXbm0QK9hKj6its8W11b7gQRnWTJlYTWgYxIDye3Q2+244LkmFrp9tcs2144389R tt5A== X-Gm-Message-State: AOAM532LT0KJ6s9V3UqsO7kjBUgZLhd7NoIYwMYbE55M9eoAbM1+p5GJ 3HO3ef+H674urJJfmTKD2PNubQ== X-Google-Smtp-Source: ABdhPJwmmHgiFaWnjRljKgSdj7Q1Wrf7FJQbi5FMZjnUD3Vm8dho6daBPalirc/2BVyVB2AViDwBZA== X-Received: by 2002:a17:902:326:: with SMTP id 35mr30625569pld.301.1593043693448; Wed, 24 Jun 2020 17:08:13 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:24fa:e766:52c9:e3b2]) by smtp.gmail.com with ESMTPSA id dw17sm5905866pjb.40.2020.06.24.17.08.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 17:08:12 -0700 (PDT) From: Douglas Anderson To: Andy Gross , Bjorn Andersson Cc: linux-arm-msm@vger.kernel.org, swboyd@chromium.org, Douglas Anderson , Rob Herring , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] arm64: dts: qcom: sc7180: Switch SPI to use GPIO for CS Date: Wed, 24 Jun 2020 17:08:04 -0700 Message-Id: <20200624170746.1.I997a428f58ef9d48b37a27a028360f34e66c00ec@changeid> X-Mailer: git-send-email 2.27.0.212.ge8ba1cc988-goog MIME-Version: 1.0 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org The geni SPI protocol appears to have been designed without taking Linux needs into account. In all the normal flows it takes care of setting chip select itself. However, Linux likes to manage the chip select so it can do fancy things. Back when we first landed the geni SPI driver we worked around this by: - Always setting the FRAGMENTATION bit in transfers, which (I believe) tells the SPI controller not to mess with the chip select during transfers. - Controlling the chip select manually by sending the SPI controller commands to assert or deassert the chip select. Our workaround was fine and it's been working OK, but it's really quite inefficient. A normal SPI transaction now needs to do: 1. Start a command to set the chip select. 2. Wait for an interrupt from controller saying chip select done. 3. Do a transfer. 4. Start a command to unset the chip select. 5. Wait for an interrupt from controller saying chip select done. Things are made a bit worse because the Linux GPIO framework assumes that setting a chip select is quick. Thus the SPI core can be seen to tell us to set our chip select even when it's already in the right state and we were dutifully kicking off commands and waiting for interrupts. While we could optimize that particular case, we'd still be left with the slowness when we actually needed to toggle the chip select. All the chip select lines can actually be muxed to be GPIOs and there's really no downside in doing so. Now Linux can assert and deassert the chip select at will with a simple MMIO write. The SPI driver will still have the ability to set the chip select, but not we just won't use it. With this change I tested reading the firmware off the EC connected to a ChromeOS device (flashrom -p ec -r ...). I saw about a 25% speedup in total runtime of the command and a 30% reduction in interrupts generated (measured by /proc/interrupts). Signed-off-by: Douglas Anderson Reviewed-by: Stephen Boyd --- arch/arm64/boot/dts/qcom/sc7180.dtsi | 57 ++++++++++++++++++++++++---- 1 file changed, 49 insertions(+), 8 deletions(-) diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi index 3a8076c8bdbf..74c8503b560e 100644 --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -570,6 +571,7 @@ spi0: spi@880000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi0_default>; interrupts = ; + cs-gpios = <&tlmm 37 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -607,6 +609,7 @@ spi1: spi@884000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi1_default>; interrupts = ; + cs-gpios = <&tlmm 3 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -668,6 +671,7 @@ spi3: spi@88c000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi3_default>; interrupts = ; + cs-gpios = <&tlmm 41 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -729,6 +733,7 @@ spi5: spi@894000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi5_default>; interrupts = ; + cs-gpios = <&tlmm 28 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -779,6 +784,7 @@ spi6: spi@a80000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi6_default>; interrupts = ; + cs-gpios = <&tlmm 62 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -840,6 +846,7 @@ spi8: spi@a88000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi8_default>; interrupts = ; + cs-gpios = <&tlmm 45 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -901,6 +908,7 @@ spi10: spi@a90000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi10_default>; interrupts = ; + cs-gpios = <&tlmm 89 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -938,6 +946,7 @@ spi11: spi@a94000 { pinctrl-names = "default"; pinctrl-0 = <&qup_spi11_default>; interrupts = ; + cs-gpios = <&tlmm 56 GPIO_ACTIVE_LOW>; #address-cells = <1>; #size-cells = <0>; status = "disabled"; @@ -1204,65 +1213,97 @@ pinmux { qup_spi0_default: qup-spi0-default { pinmux { pins = "gpio34", "gpio35", - "gpio36", "gpio37"; + "gpio36"; function = "qup00"; }; + pinmux-cs { + pins = "gpio37"; + function = "gpio"; + }; }; qup_spi1_default: qup-spi1-default { pinmux { pins = "gpio0", "gpio1", - "gpio2", "gpio3"; + "gpio2"; function = "qup01"; }; + pinmux-cs { + pins = "gpio3"; + function = "gpio"; + }; }; qup_spi3_default: qup-spi3-default { pinmux { pins = "gpio38", "gpio39", - "gpio40", "gpio41"; + "gpio40"; function = "qup03"; }; + pinmux-cs { + pins = "gpio41"; + function = "gpio"; + }; }; qup_spi5_default: qup-spi5-default { pinmux { pins = "gpio25", "gpio26", - "gpio27", "gpio28"; + "gpio27"; function = "qup05"; }; + pinmux-cs { + pins = "gpio28"; + function = "gpio"; + }; }; qup_spi6_default: qup-spi6-default { pinmux { pins = "gpio59", "gpio60", - "gpio61", "gpio62"; + "gpio61"; function = "qup10"; }; + pinmux-cs { + pins = "gpio62"; + function = "gpio"; + }; }; qup_spi8_default: qup-spi8-default { pinmux { pins = "gpio42", "gpio43", - "gpio44", "gpio45"; + "gpio44"; function = "qup12"; }; + pinmux-cs { + pins = "gpio45"; + function = "gpio"; + }; }; qup_spi10_default: qup-spi10-default { pinmux { pins = "gpio86", "gpio87", - "gpio88", "gpio89"; + "gpio88"; function = "qup14"; }; + pinmux-cs { + pins = "gpio89"; + function = "gpio"; + }; }; qup_spi11_default: qup-spi11-default { pinmux { pins = "gpio53", "gpio54", - "gpio55", "gpio56"; + "gpio55"; function = "qup15"; }; + pinmux-cs { + pins = "gpio56"; + function = "gpio"; + }; }; qup_uart0_default: qup-uart0-default {