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<79f6560e-dbb5-0ae1-49f8-cf1cd95396ec@nvidia.com> <20200427074837.GC3451400@ulmo> <20200427110033.GC3464906@ulmo> <3a06811c-02dc-ce72-ebef-78c3fc3f4f7c@gmail.com> <20200427151234.GE3464906@ulmo> <1ab276cf-c2b0-e085-49d8-b8ce3dba8fbe@gmail.com> <20200429081448.GA2345465@ulmo> <20200429085502.GB2345465@ulmo> <9e36c4ec-ca02-bd15-d765-15635f09db4b@gmail.com> From: Jon Hunter Message-ID: <7442f4cd-6406-41f6-5c9b-932bff8ad5b2@nvidia.com> Date: Wed, 29 Apr 2020 14:57:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <9e36c4ec-ca02-bd15-d765-15635f09db4b@gmail.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To DRHQMAIL107.nvidia.com (10.27.9.16) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: quoted-printable DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1588168555; bh=WwxbsSS15NCrITtXPPngnki2MjBPnDYjFM5z5nJZgeM=; h=X-PGP-Universal:Subject:To:CC:References:From:Message-ID:Date: User-Agent:MIME-Version:In-Reply-To:X-Originating-IP: X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=Pa53bR205F4LjkoRmYoj4tJO4IMvE4BSd3+5sTMBjDdE5mlDfdO4OSGbOMKBWTB5H mbZt5cVglP+YMRIQd8FuLRSzcYx2bm+VDGnwSGLcxVRMRME31dSIup3WRmtbjvVCh/ L67QpB706EHnfLP9qsAHJsAfn2IcKLBur69rhIMtAl+g2UdfVAP9ml1GE8btmjXC0+ pJRjSKEMCAe/XEd3QXA3jR0vpuuuwH9k7YR8w8UBR1fgCrDRsAZqq192tXH9s3Tpc5 1+ajhNiInnnq2MKjCnmBqynsEBQtWaUdL+BJTV8NfyPjYReGEH/uHrhXcDlzp58bAb UwVHN+GLzKm7Q== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/04/2020 13:35, Dmitry Osipenko wrote: > 29.04.2020 11:55, Thierry Reding =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > ... >>>> It's not "papering over an issue". The bug can't be fixed properly >>>> without introducing I2C atomic transfers support for a late suspend >>>> phase, I don't see any other solutions for now. Stable kernels do not >>>> support atomic transfers at all, that proper solution won't be backpor= table. >>> >>> Hm... on a hunch I tried something and, lo and behold, it worked. I can >>> get Cardhu to properly suspend/resume on top of v5.7-rc3 with the >>> following sequence: >>> >>> revert 9f42de8d4ec2 i2c: tegra: Fix suspending in active runtime PM st= ate >>> apply http://patchwork.ozlabs.org/project/linux-tegra/patch/2019121313= 4417.222720-1-thierry.reding@gmail.com/ >>> >>> I also ran that through our test farm and I don't see any other issues. >>> At the time I was already skeptical about pm_runtime_force_suspend() an= d >>> pm_runtime_force_resume() and while I'm not fully certain why exactly i= t >>> doesn't work, the above on top of v5.7-rc3 seems like a good option. >>> >>> I'll try to do some digging if I can find out why exactly force suspend >>> and resume doesn't work. >> >> Ah... so it looks like pm_runtime_force_resume() never actually does >> anything in this case and then disable_depth remains at 1 and the first >> tegra_i2c_xfer() will then fail to runtime resume the controller. >=20 > That's the exactly expected behaviour of the RPM force suspend/resume. > The only unexpected part for me is that the tegra_i2c_xfer() runtime > resume then fails in the NOIRQ phase. From reading the changelog for commit 1e2ef05bb8cf ("PM: Limit race conditions between runtime PM and system sleep (v2))", this is the expected behaviour for runtime resume in the noirq phase. Jon --=20 nvpublic