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<1f4c5185-e518-5674-4a8c-4e7db64aa0d3@nvidia.com> From: Sameer Pujar Message-ID: Date: Mon, 28 Jan 2019 11:36:58 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <1f4c5185-e518-5674-4a8c-4e7db64aa0d3@nvidia.com> X-Originating-IP: [172.20.13.39] X-ClientProxiedBy: HQMAIL103.nvidia.com (172.20.187.11) To HQMAIL101.nvidia.com (172.20.187.10) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-GB DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1548655598; bh=GFZcwXLa6LPwIIvxavnHw88/gvFXO3VncSuyrjhKamY=; 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-Transfer-Encoding: Content-Language; b=T9prp+ImgkKAeujHQRjvvREqpaaJCTgosA8b3uTCWbWWvMNUABuWHGRh7wR61urgt UPRiH9+7z/tWex9o9446/61PxsqCCW3iYVQE59lt4xBm/BW40S9Ikdz4BeMaBM0vA6 Vxnm1xndmRMfQyJTIh2CItoCBfu88sSVLDqrG8sihoJmwCv86pFfAmubemb0+T+2OL XeqFgnpHIyNqUX0+edFc/aOZMNzCn2JfQ5qekQo+lJ866CbTz/teWMlZ7U/0xEFOaO 7s/TaHo5oWH/jUq0cWEpDLMZNhED2huGquDbYV/q4AxxDhwzwfA+sujtd0HpAQ2gay uhP1vOEbhq8+g== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/25/2019 7:34 PM, Jon Hunter wrote: > 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 :-) Do we have a consensus here? Request others to provide opinions to help close on this. Thanks, Sameer. > Jon >