From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sameer Pujar Subject: Re: [PATCH v3] regmap: add iopoll-like atomic polling macro Date: Fri, 10 Jan 2020 10:20:05 +0530 Message-ID: References: <1578546590-24737-1-git-send-email-spujar@nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Osipenko , broonie@kernel.org Cc: jonathanh@nvidia.com, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org List-Id: linux-tegra@vger.kernel.org On 1/9/2020 7:27 PM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 09.01.2020 10:24, Sameer Pujar =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >> On 1/9/2020 11:30 AM, Dmitry Osipenko wrote: >>> External email: Use caution opening links or attachments >>> >>> >>> 09.01.2020 08:09, Sameer Pujar =D0=BF=D0=B8=D1=88=D0=B5=D1=82: >>>> This patch adds a macro 'regmap_read_poll_timeout_atomic' that works >>>> similar to 'readx_poll_timeout_atomic' defined in linux/iopoll.h; This >>>> is atomic version of already available 'regmap_read_poll_timeout' macr= o. >>>> >>>> It should be noted that above atomic macro cannot be used by all >>>> regmaps. >>>> If the regmap is set up for atomic use (flat or no cache and MMIO) the= n >>>> only it can use. >>>> >>>> Signed-off-by: Sameer Pujar >>>> --- >>> Could you please explain what is the targeted use-case here? >> I was trying to use regmap_read_poll_timeout() to poll for status change >> of a register. This resulted in "BUG: scheduling while atomic". The >> callback function, in which I was trying to use the macro, runs in >> atomic context. Hence new atomic macro is added. I was checking ALSA >> playback/capture and trigger() callback had to monitor some register >> status. >> >> In general, the new macro can be used in atomic callbacks where regmap >> interface is used and polling is required. >> > You should send a full patchset because it may turn out that the patch > which makes use of the new feature isn't correct or maybe the new > feature isn't really needed. > > If there was a previous discussion about the need for this change, then > you should provide a link to that discussion. > > Please note that usually changes without a real use-case in kernel are > not getting picked up or they are getting removed later on if nobody > makes use of them, so I assume this is a kind of an RFC patch for now. OK. I will send this as part of the complete series. Thank you.