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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 019D6C433FE for ; Sat, 22 Oct 2022 10:56:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230336AbiJVK4V (ORCPT ); Sat, 22 Oct 2022 06:56:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36968 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230481AbiJVK4E (ORCPT ); Sat, 22 Oct 2022 06:56:04 -0400 Received: from mail-ed1-x534.google.com (mail-ed1-x534.google.com [IPv6:2a00:1450:4864:20::534]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9ED2E2FC5A3; Sat, 22 Oct 2022 03:13:58 -0700 (PDT) Received: by mail-ed1-x534.google.com with SMTP id r14so14446268edc.7; Sat, 22 Oct 2022 03:13:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlemail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=06Eh/nhcc2dk5YHgUHqVnCwIQ6d3gtHqF6ndFEyn00o=; b=VMuZTZXRwDpR3O+afkcfnJXAjQaa5SZKkHcYlMnVcwYNqOFKFxdi0LFa6WPSQTKNM/ pc5fiF04hiUnP4DSCczNQyvQnbN4AESxQECufjLjtfKnqrc2XPmpgpeNDR7z2bs4+CHL IvxEmFJCZ4uAe2JcieU3RgEEe8ustULxygdjz8h62X8fClJKGJOxjr2kcqtm9V/C4mwv yE0qxdwqHcSimSx+euw2ho3YtC6fIVUsyvNQKYfQMgkoPu104g3gYBtWIeZiHzwa2X3P Z9a6e48lhW1bTuubdJt+KuMtq8fuANAk9+DD21gRtOqQNpE5bj8W7pO+mWUV8oGMa6n6 OcWQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=06Eh/nhcc2dk5YHgUHqVnCwIQ6d3gtHqF6ndFEyn00o=; b=Xgfzcd+8X0rAhGvuC5MoEy4r9s6iO7+27K0emNHr49Eh1V7G/HGk2Dp9SDmQGUYMd7 MYI15XY0R2JfRV6RybjCusfBjQvSPKytpw7XOYm4TeRepYLMaoUgFUOCp8sqY42sh4/v /GWMlz21i4o/rVMZZaeQ5c5DnKohgDejKUrGDwYbG/7fhmNRRfjuNg+mtwpGptX3BIf+ 5omtDskMJswvBBbReu1IkxIfXMyzMO7CMt470+1GCx0ynKmJKHBq9toaRFHbl4b5AIvk 7vOUMOC8J7edlfOU7ZC38wg09bGgW+XK8QQXatCGrwvkPO60irNCgxd9JSZ78pt1Z+tA +Ziw== X-Gm-Message-State: ACrzQf1dW/moNpcBRgQ/S/jylWReRDmw77oXbUqjoRoMZsqnmPLlHm1h S0TUQw+HD1sP23SxlfisTxDt+/0VXUzZ0NP7Jhg= X-Google-Smtp-Source: AMsMyM7QaRZd6ahXj6EN8TYBfKGXqZyCiosKZRQy5INk2+Si4bfGFYLHkGLRXI+5OCESdg4fjJkhVuQqUiCbjUV96RM= X-Received: by 2002:a17:906:7314:b0:791:a45a:bc84 with SMTP id di20-20020a170906731400b00791a45abc84mr17664692ejc.394.1666433634815; Sat, 22 Oct 2022 03:13:54 -0700 (PDT) MIME-Version: 1.0 References: <20221004-up-aml-fix-spi-v4-0-0342d8e10c49@baylibre.com> <20221004-up-aml-fix-spi-v4-2-0342d8e10c49@baylibre.com> In-Reply-To: <20221004-up-aml-fix-spi-v4-2-0342d8e10c49@baylibre.com> From: Martin Blumenstingl Date: Sat, 22 Oct 2022 12:13:43 +0200 Message-ID: Subject: Re: [PATCH v4 2/4] spi: meson-spicc: Use pinctrl to drive CLK line when idle To: Amjad Ouled-Ameur Cc: Kevin Hilman , Jerome Brunet , Rob Herring , Neil Armstrong , Krzysztof Kozlowski , Mark Brown , linux-amlogic@lists.infradead.org, Da Xue , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org On Fri, Oct 21, 2022 at 3:31 PM Amjad Ouled-Ameur wrote: > > Between SPI transactions, all SPI pins are in HiZ state. When using the SS > signal from the SPICC controller it's not an issue because when the > transaction resumes all pins come back to the right state at the same time > as SS. > > The problem is when we use CS as a GPIO. In fact, between the GPIO CS > state change and SPI pins state change from idle, you can have a missing or > spurious clock transition. > > Set a bias on the clock depending on the clock polarity requested before CS > goes active, by passing a special "idle-low" and "idle-high" pinctrl state > and setting the right state at a start of a message > > Reported-by: Da Xue > Signed-off-by: Neil Armstrong > Signed-off-by: Amjad Ouled-Ameur Reviewed-by: Martin Blumenstingl