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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id E3F22C83F1A for ; Mon, 21 Jul 2025 16:42:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=vrALdPoLpJLxw/uGBfJ0v3RJvIxBGmQxgCinSpZhuVg=; b=gl2yhby1epIj8HY+E8seq46Q0m 29tSYpZ7ioS42WYU6eBuPGqpeMlV78xoZ8TTAkPZgugl1yOom/txbF8jDZXf+EuglvwW5m3Q2Getu cq7GU4D3+XxlkAhyr55Xr5+QP7GaY0YuP81lCFhLey8bbfUswFqmhzwMMY5/v+EGEQT0vxHUwTON/ eNIwGQTOhLFEBwmUZ9ggBzq3sDWh5UKhpSLspEFJZGInGv6Z/DwJlPiyYNnP62s0+3Rs5+l79tUav TZNnmUA3b6KouErcuR4NOjI4SbaypYCGMV60/zPiPtKRfDnfdOyHMZ2hzquS2vqWMPR3DpStQaVDI J+SbTI7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1udtaz-00000000Boq-0diT; Mon, 21 Jul 2025 16:42:33 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1udr3h-0000000HRxS-2PaN for linux-arm-kernel@lists.infradead.org; Mon, 21 Jul 2025 14:00:02 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D99DC153B; Mon, 21 Jul 2025 06:59:54 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4CA5A3F66E; Mon, 21 Jul 2025 07:00:00 -0700 (PDT) Date: Mon, 21 Jul 2025 14:59:58 +0100 From: Leo Yan To: Suzuki K Poulose Cc: Mike Leach , James Clark , Anshuman Khandual , Alexander Shishkin , Greg Kroah-Hartman , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 04/10] coresight: Appropriately disable programming clocks Message-ID: <20250721135958.GE3137075@e132581.arm.com> References: <20250627-arm_cs_fix_clock_v4-v4-0-0ce0009c38f8@arm.com> <20250627-arm_cs_fix_clock_v4-v4-4-0ce0009c38f8@arm.com> <5a5f1355-563d-498a-9dec-3479a257b3e6@arm.com> <20250721104834.GC3137075@e132581.arm.com> <607c03a2-267c-46e6-a7fa-e733c1970e60@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <607c03a2-267c-46e6-a7fa-e733c1970e60@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250721_070001_663012_DC2C4E1A X-CRM114-Status: GOOD ( 19.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 21, 2025 at 12:40:38PM +0100, Suzuki Kuruppassery Poulose wrote: > On 21/07/2025 11:48, Leo Yan wrote: > > On Mon, Jul 21, 2025 at 10:15:22AM +0100, Suzuki Kuruppassery Poulose wrote: > > > > [...] > > > > > > diff --git a/include/linux/coresight.h b/include/linux/coresight.h > > > > index 4ac65c68bbf44b98db22c3dad2d83a224ce5278e..dd2b4cc7a2b70cf060a3207548fe80e3824c489f 100644 > > > > --- a/include/linux/coresight.h > > > > +++ b/include/linux/coresight.h > > > > @@ -480,26 +480,16 @@ static inline bool is_coresight_device(void __iomem *base) > > > > * Returns: > > > > * > > > > * clk - Clock is found and enabled > > > > - * NULL - clock is not found > > > > > > This is still valid, right ? > > > > No. Since this patch uses devm_clk_get_enabled() to get a clock, if the > > pclk is not found, it returns -ENOENT (see of_parse_clkspec()). > > > > Only the optional clock APIs (e.g., devm_clk_get_optional_enabled()) > > return a NULL pointer instead of -ENOENT when the clock is not found. > > This will break ACPI based systems, as we may not have a "pclk" described > for them. We should be able to tolerate "no pclk" Get it. How about change the code like below? static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev) { struct clk *pclk; pclk = devm_clk_get_enabled(dev, "apb_pclk"); if (IS_ERR(pclk)) pclk = devm_clk_get_enabled(dev, "apb"); /* Tolerate no pclk for ACPI device */ if ((pclk == ERR_PTR(-ENOENT)) && has_acpi_companion(dev)) return NULL; return pclk; }