From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 41F2A2D8DD6 for ; Mon, 21 Jul 2025 14:00:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753106402; cv=none; b=aHy1YuUNVCQd7hiQHI4RjBLUuKBExIbYqEvpPRTP1QsEljSqSjEyrYPPLRgohvel2NuR+7aoxgYpmBAIbRQiZ5K9hMHoV4iK1Ylhf67ATftv5pTNY0tW0Iw+0Ka6dPGgfYYhDTyY2bkttK+Arc8PP4TvbrTM0FFWUTCnhYtYwX8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753106402; c=relaxed/simple; bh=QRro4iNQid9d7xN7JufpQ6+idVYr9FxuniHrLYzKwz8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=sdAuUv3sSEK8VnUBtOHRT2MBq+lbUAK6S2Pbz4bKKqN6UY0IJBLkmpmlVSjfcQLbhWKchGR7mXHPnWFI/CjtHAHVb22Zaf5KgX+VNuUQv0KQ/wLsxvF1dNlmUVFZnwIfS5cyMcHT8YUGA9g7WV04s0Ve4k0jv3qwmy16hKv/ojI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <607c03a2-267c-46e6-a7fa-e733c1970e60@arm.com> 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; }