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From: Jon Hunter Message-ID: <1f4c5185-e518-5674-4a8c-4e7db64aa0d3@nvidia.com> Date: Fri, 25 Jan 2019 14:04:56 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1548425100; bh=cMHGwQhGfnxvoTzmgYSvcaJzUhzFBmhRQUHVrzVuKks=; 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=gJxlosgzR3EhHfLUI0EImjVoVYe671poiibuCiGdkOJbSmkzTsnce+MiFXhNfosGQ wax/TPeAZ6SLlAoCkz4SsJncFuNwz4uXPxMmr6N1cUmxf8MqpimZ8pnEx4n3BwB1Uh El+JPw8mWXJ9NJFSYiEx1IxOin4/umVUEYC0Kkef8sSXnxPRNRhpiV/F26oN3yl2c3 ppFSJfApD+EAs5b/tjcpukIwNW0V0vdYd1AxoEszdMo0AcRkLhh7hjz1WxncIb5GP2 sHOK9bwovxfjzLR1W0HQS6DLYXurQCcSzIvn4v0I+gm+tKBWdXZrBa7OW+lFnpEBo1 7OGbYXB8epnDQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/01/2019 13:58, Takashi Iwai wrote: > On Fri, 25 Jan 2019 14:26:27 +0100, > Jon Hunter wrote: >> >> >> On 25/01/2019 12:40, Takashi Iwai wrote: >>> On Fri, 25 Jan 2019 12:36:00 +0100, >>> Jon Hunter wrote: >>>> >>>> >>>> On 24/01/2019 19:08, Takashi Iwai wrote: >>>>> On Thu, 24 Jan 2019 18:36:43 +0100, >>>>> Sameer Pujar wrote: >>>>>> >>>>>> If CONFIG_PM is disabled or runtime PM calls are forbidden, the clocks >>>>>> will not be ON. This could cause issue during probe, where hda init >>>>>> setup is done. This patch checks whether runtime PM is enabled or not. >>>>>> If disabled, clocks are enabled in probe() and disabled in remove() >>>>>> >>>>>> This patch does following minor changes as cleanup, >>>>>> * return code check for pm_runtime_get_sync() to take care of failure >>>>>> and exit gracefully. >>>>>> * In remove path runtime PM is disabled before calling snd_card_free(). >>>>>> * hda_tegra_disable_clocks() is moved out of CONFIG_PM_SLEEP check. >>>>>> * runtime PM callbacks moved out of CONFIG_PM check >>>>>> >>>>>> Signed-off-by: Sameer Pujar >>>>>> Reviewed-by: Ravindra Lokhande >>>>>> Reviewed-by: Jon Hunter >>>>> (snip) >>>>>> @@ -555,6 +553,13 @@ static int hda_tegra_probe(struct platform_device *pdev) >>>>>> if (!azx_has_pm_runtime(chip)) >>>>>> pm_runtime_forbid(hda->dev); >>>>>> >>>>>> + /* explicit resume if runtime PM is disabled */ >>>>>> + if (!pm_runtime_enabled(hda->dev)) { >>>>>> + err = hda_tegra_runtime_resume(hda->dev); >>>>>> + if (err) >>>>>> + goto out_free; >>>>>> + } >>>>>> + >>>>>> schedule_work(&hda->probe_work); >>>>> >>>>> Calling runtime_resume here is really confusing... >>>> >>>> Why? IMO it is better to have a single handler for resuming the device >>>> and so if RPM is not enabled we call the handler directly. This is what >>>> we have been advised to do in the past and do in other drivers. See ... >>> >>> The point is that we're not "resuming" anything there. It's in the >>> early probe stage, and the device state is uninitialized, not really >>> suspended. It'd end up with just calling the same helper >>> (hda_tegra_enable_clocks()), though. >> >> Yes and you can make the same argument for every driver that calls >> pm_runtime_get_sync() during probe to turn on clocks, handle resets, >> etc, because at the end of the day the very first call to >> pm_runtime_get_sync() invokes the runtime_resume callback, when we have >> never been suspended. > > Although there are some magical pm_runtime_*() in some places, most of > such pm_runtime_get_sync() is for the actual runtime PM management (to > prevent the runtime suspend), while the code above is for explicitly > setting up something for non-PM cases. > > And if pm_runtime_get_sync() is obviously superfluous, we should > remove such calls. Really. Yes agree. >> Yes at the end of the day it is the same and given that we have done >> this elsewhere I think it is good to be consistent if/where we can. > > The code becomes less readable, and that's a good reason against it :) I don't its less readable. However, I do think it is less error prone :-) Jon -- nvpublic