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 C5623C4708E for ; Mon, 2 Jan 2023 13:22:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231793AbjABNWI (ORCPT ); Mon, 2 Jan 2023 08:22:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34692 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232631AbjABNWC (ORCPT ); Mon, 2 Jan 2023 08:22:02 -0500 Received: from mail.3ffe.de (0001.3ffe.de [IPv6:2a01:4f8:c0c:9d57::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80CAFB66; Mon, 2 Jan 2023 05:22:01 -0800 (PST) Received: from 3ffe.de (0001.3ffe.de [IPv6:2a01:4f8:c0c:9d57::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mail.3ffe.de (Postfix) with ESMTPSA id D997D89; Mon, 2 Jan 2023 14:21:59 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=walle.cc; s=mail2022082101; t=1672665719; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fFvEm4TS0m0oMTUcPbTdYrNtVbBi+eT7RCIgcBGxXUk=; b=Q/IU0tbBUb3lVx+NKUnYufg7JfbR6kQfbqGofZoUs3fLrhEke7TsnNoS+yi/Yw/ONaYMC0 +Uhg+eP9/g+OHogid2o1V+cRdwce5mB0TTOrLf1f1XbuSffbZH9gMXajbTPDILPivYAfUf 2wBnuNuDueeqfFcX7BCTRLJIpCbcbWXYFVwEAbWzOaVtB3CiTxACymLERTnACkFM9J/6eo nLxHYQ/xR5czBH0h8FipaWYKpc6pt0P7iBKXlqU2vEftiYYpidFsZuMcPdctpagFFkg054 K5gjlBhwiKRvUnlCCRoO+J2tm8eHHXezVOwK/ooDZHMfI1EGk2drC5Rj7nZDxw== MIME-Version: 1.0 Date: Mon, 02 Jan 2023 14:21:59 +0100 From: Michael Walle To: Tudor Ambarus Cc: Mark Brown , tudor.ambarus@microchip.com, alexandre.belloni@bootlin.com, claudiu.beznea@microchip.com, devicetree@vger.kernel.org, krzysztof.kozlowski+dt@linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org, linux-spi@vger.kernel.org, nicolas.ferre@microchip.com, robh+dt@kernel.org Subject: Re: [PATCH 1/8] spi: dt-bindings: Introduce spi-cs-setup-ns property In-Reply-To: <1ee9cf77-1ca0-6e4e-ba7d-896838bd71de@linaro.org> References: <20221117105249.115649-2-tudor.ambarus@microchip.com> <20221118141458.954646-1-michael@walle.cc> <28da9e33-57e8-7ac1-7e6c-13c297a945d6@gmail.com> <1ee9cf77-1ca0-6e4e-ba7d-896838bd71de@linaro.org> User-Agent: Roundcube Webmail/1.4.13 Message-ID: <5ed88e3c3c105fdce1bb16ff16cde32f@walle.cc> X-Sender: michael@walle.cc Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org >>>>>> +  spi-cs-setup-ns: >>>>>> +    description: >>>>>> +      Delay in nanosecods to be introduced by the controller >>>>>> after CS is >>>>>> +      asserted. >>>> >>>>> Does this need a type as the spi-cs-setup-ns is apparently just >>>>> 16bit? At >>>>> least the driver uses it that way. >>>> >>>>> But IMHO this should just be a normal uint32 value to be consistent >>>>> with >>>>> all the other properties. Also the max value with 16bit will be >>>>> 'just' >>>>> 65us. >>>> >>>> Making it 32 bit does seem safer.  I've applied the series >>> >>> Thanks. There are few implications to consider before making this >>> prop a >>> u32, and I'd like to check them with you. >>> >>> struct spi_delay will have to be updated to have a u32 value, now >>> it's a >>> u16. This means that we'll have to update spi_delay_to_ns() to either >>> return a s64 or to add a u64 *delay parameter to the function so that >>> we >>> can still handle the conversions from usecs and the error codes in >>> the >>> SPI_DELAY_UNIT_SCK case. Then all its callers have to be updated to >>> consider the u64 delay. >> >> I was talking about the device tree property. Even if the driver >> continue >> to use just 16bit, the DT property could be 32bit IMHO. > > but then you'll have an implicit cast to u16 at: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/spi/spi.c#n2314 > which will make the u32 dt prop misleading. Nothing will prevent you from checking for a valid range and return an error :) But I agree, that converting the u16 to u32 in the driver is probably the better way. >> At the moment, the schema says its 32bit (if I'm not mistaken, because >> it doesn't have a type), but the driver will parse the property as >> 16bit and your device tree also has this /bits/ thingy. So regardless >> if the driver is using 16bit or 32bit for the value, there seems to be >> a discrepancy between the schema and the devicetree (and driver). > > okay, thanks for pointing it out. Let's decide how we fix this. > >> >> All other properties are just the regular 32bit values, thus I was >> suggesting to change the DT property to 32bit. > > If we want to change the dt prop to 32bit I think we should also handle > the parsed value as u32, not as u16. Strictly speaking, your device tree is wrong, because the schema already says it's 32bit. -michael