From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Subject: Re: [PATCH 1/1] base: power: runtime: Export pm_runtime_get/put_suppliers Date: Fri, 8 Dec 2017 14:21:36 +0100 Message-ID: <20171208132136.GA26631@kroah.com> References: <1512736247-16538-1-git-send-email-vivek.gautam@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33892 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752965AbdLHNVa (ORCPT ); Fri, 8 Dec 2017 08:21:30 -0500 Content-Disposition: inline In-Reply-To: <1512736247-16538-1-git-send-email-vivek.gautam@codeaurora.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: Vivek Gautam Cc: rjw@rjwysocki.net, len.brown@intel.com, pavel@ucw.cz, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, sboyd@codeaurora.org, robdclark@gmail.com, robin.murphy@arm.com, will.deacon@arm.com, linux-arm-msm@vger.kernel.org On Fri, Dec 08, 2017 at 06:00:47PM +0530, Vivek Gautam wrote: > The device link allows the pm framework to tie the supplier and > consumer. So, whenever the consumer is powered-on, the supplier > is powered-on first. > > There are however cases in which the consumer wants to power-on > the supplier, but not itself. > E.g., A Graphics or multimedia driver wants to power-on the SMMU > to unmap a buffer and finish the TLB operations without powering > on itself. Some of these unmap requests are coming from the > user space when the controller itself is not powered-up, and it > can be huge penalty in terms of power and latency to power-up > the graphics/mm controllers. > There can be an argument that the supplier should handle this case > on its own and there should not be a need for the consumer to > power-on the supplier. But as discussed on the thread [1] about > ARM-SMMU runtime pm, we don't want to introduce runtime pm calls > in atomic paths, such as in arm_smmu_unmap. > > [1] https://patchwork.kernel.org/patch/9827825/ > > Signed-off-by: Vivek Gautam > --- > drivers/base/power/runtime.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c > index 027d159ac381..af169304ca13 100644 > --- a/drivers/base/power/runtime.c > +++ b/drivers/base/power/runtime.c > @@ -1578,6 +1578,7 @@ void pm_runtime_get_suppliers(struct device *dev) > > device_links_read_unlock(idx); > } > +EXPORT_SYMBOL_GPL(pm_runtime_get_suppliers); We do not export symbols unless there are in-kernel users of them. Where is the patch that adds a user for these functions? thanks, greg k-h