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[86.49.110.70]) by smtp.gmail.com with ESMTPSA id v19sm28570077wrd.46.2018.12.05.04.29.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 05 Dec 2018 04:29:23 -0800 (PST) Subject: Re: [PATCH] clk: vc5: Add suspend/resume support To: Laurent Pinchart Cc: Stephen Boyd , linux-clk@vger.kernel.org, Marek Vasut , Alexey Firago , Michael Turquette , Stephen Boyd , linux-renesas-soc@vger.kernel.org References: <20181204182721.28258-1-marek.vasut+renesas@gmail.com> <154395675529.88331.12886650536645714742@swboyd.mtv.corp.google.com> <4f85447d-07b8-9f4c-ecb2-25d6834e6c5d@gmail.com> <2439179.Yi0TbQOvfy@avalon> From: Marek Vasut Message-ID: <5bd189ca-2bac-58ce-a635-58f515962f82@gmail.com> Date: Wed, 5 Dec 2018 13:29:22 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <2439179.Yi0TbQOvfy@avalon> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-clk-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-clk@vger.kernel.org On 12/05/2018 06:21 AM, Laurent Pinchart wrote: > Hi Marek, > > On Wednesday, 5 December 2018 01:48:01 EET Marek Vasut wrote: >> On 12/04/2018 09:52 PM, Stephen Boyd wrote: >>> Quoting Marek Vasut (2018-12-04 10:27:21) >>> >>>> diff --git a/drivers/clk/clk-versaclock5.c >>>> b/drivers/clk/clk-versaclock5.c >>>> index decffb3826ec..ac90fb36af1a 100644 >>>> --- a/drivers/clk/clk-versaclock5.c >>>> +++ b/drivers/clk/clk-versaclock5.c >>>> @@ -906,6 +906,39 @@ static int vc5_remove(struct i2c_client *client) >>>> >>>> return 0; >>>> >>>> } >>>> >>>> +#ifdef CONFIG_PM_SLEEP >>>> +static int vc5_suspend(struct device *dev) >>> >>> Please mark as __maybe_unused and drop the #ifdef CONFIG_PM_SLEEP >>> >>>> +{ >>>> + struct vc5_driver_data *vc5 = dev_get_drvdata(dev); >>>> + int ret; >>>> + >>>> + ret = regcache_sync(vc5->regmap); >>>> + if (ret != 0) { >>>> + dev_err(dev, "Failed to save register map: %d\n", ret); >>>> + return ret; >>> >>> Do we need to block suspend if we can't save the register map away? Or >>> can we just throw up our hands and not restore on resume? >> >> Some hardware will fail on resume, so I'd say -- yes ? > > But why do you need to sync on suspend in the first place ? What could cause > the map to be dirty at this stage, and require syncing before suspend, that > couldn't work with the sync be delayed to resume time ? Possibly a configuration coming from eg. bootloader time , or some other configuration not done by Linux. -- Best regards, Marek Vasut