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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 2A6C6C433FF for ; Fri, 2 Aug 2019 14:42:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E855A21726 for ; Fri, 2 Aug 2019 14:42:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564756949; bh=35vK+ar+Nb48ekiE/YuVGT1lyA6NEm0vIuOltepn4ZY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:List-ID:From; b=WS3mzUPdPfxG+PmdLBuaszTwwIzLg86ekmKFwOxrd2MBNP8oGyOPHMrZgqZCzofNF MTkredCAr6OQzmRjvVhk09lMz6R8+ZrZ5M3QVjl1Vprqaz46CESX0a1mcI/ELmPGmm 9UOe7VWMJ6HbjilbeEkO4fAD86eZ7CxsxVYYmRBs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395011AbfHBOm2 (ORCPT ); Fri, 2 Aug 2019 10:42:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:46924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731951AbfHBOm1 (ORCPT ); Fri, 2 Aug 2019 10:42:27 -0400 Received: from [192.168.1.17] (cpe-70-114-128-244.austin.res.rr.com [70.114.128.244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3612220B7C; Fri, 2 Aug 2019 14:42:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564756946; bh=35vK+ar+Nb48ekiE/YuVGT1lyA6NEm0vIuOltepn4ZY=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=boN60vKXT6tMVuyo72YVzC0IbQ+a5sXzCgdNSxA1ySbbmVs5AUtjR+c8iU0LPOnpx LPGiv37505ALxXQTltfl/2nOCNxXZK2ZbSklU5cFBpHD0hAuRdXedlQoejQfZDY7qu k6rNwRSZwBPldvBBkk+Dmk0TSbFUxWyiSUXql6iA= Subject: Re: [PATCH] drivers/amba: add reset control to primecell probe To: Rob Herring Cc: devicetree@vger.kernel.org, "linux-kernel@vger.kernel.org" , Frank Rowand , Kees Cook , Anton Vorontsov , Colin Cross , Tony Luck , Dinh Nguyen References: <20190801184346.7015-1-dinguyen@kernel.org> From: Dinh Nguyen Openpgp: preference=signencrypt Autocrypt: addr=dinguyen@kernel.org; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/19 9:37 AM, Rob Herring wrote: > On Thu, Aug 1, 2019 at 12:44 PM Dinh Nguyen wrote: >> >> From: Dinh Nguyen >> >> The primecell controller on some SoCs, i.e. SoCFPGA, is held in reset by >> default. Until recently, the DMA controller was brought out of reset by the >> bootloader(i.e. U-Boot). But a recent change in U-Boot, the peripherals that >> are not used are held in reset and are left to Linux to bring them out of >> reset. > > You can fix this in the kernel, but any versions before this change > will remain broken. IMO, the u-boot change should be reverted because > it is breaking an ABI (though not a good one). > Right, there exists in U-Boot to support legacy platforms before this recent change. This would be for future versions. >> Add a mechanism for getting the reset property and de-assert the primecell >> module from reset if found. This is a not a hard fail if the reset property >> is not present in the device tree node, so the driver will continue to probe. > > I think this belongs in the AMBA bus code, not the DT code, as that is > where we already have clock control code for similar reasons. > Ok. >> >> Signed-off-by: Dinh Nguyen >> --- >> drivers/of/platform.c | 14 ++++++++++++++ >> 1 file changed, 14 insertions(+) >> >> diff --git a/drivers/of/platform.c b/drivers/of/platform.c >> index 7801e25e6895..d8945705313d 100644 >> --- a/drivers/of/platform.c >> +++ b/drivers/of/platform.c >> @@ -21,6 +21,7 @@ >> #include >> #include >> #include >> +#include >> >> const struct of_device_id of_default_bus_match_table[] = { >> { .compatible = "simple-bus", }, >> @@ -229,6 +230,7 @@ static struct amba_device *of_amba_device_create(struct device_node *node, >> struct amba_device *dev; >> const void *prop; >> int i, ret; >> + struct reset_control *rstc; >> >> pr_debug("Creating amba device %pOF\n", node); >> >> @@ -270,6 +272,18 @@ static struct amba_device *of_amba_device_create(struct device_node *node, >> goto err_free; >> } >> >> + /* >> + * reset control of the primecell block is optional >> + * and will not fail if the reset property is not found. >> + */ >> + rstc = of_reset_control_get_exclusive(node, "dma"); > > 'dma' doesn't sound very generic. > how about 'primecell' ? Thanks for the review! Dinh