From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sameer Pujar Subject: Re: [alsa-devel] [PATCH 4/9] ASoC: tegra: add Tegra210 based I2S driver Date: Wed, 22 Jan 2020 12:46:07 +0530 Message-ID: <3f51939d-cf4b-f69b-728a-7eb99bbae458@nvidia.com> References: <1579530198-13431-1-git-send-email-spujar@nvidia.com> <1579530198-13431-5-git-send-email-spujar@nvidia.com> <0c571858-d72c-97c2-2d6a-ead6fdde06eb@nvidia.com> <444731da-c4cd-8578-a732-c803eef31ef0@gmail.com> <598fe377-5b95-d30a-eb64-89a645166d42@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <598fe377-5b95-d30a-eb64-89a645166d42-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-GB Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dmitry Osipenko , perex-/Fr2/VpizcU@public.gmane.org, tiwai-IBi9RG/b67k@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org Cc: spujar-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, atalambedu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lgirdwood-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, viswanathl-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, sharadg-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, broonie-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, rlokhande-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, mkumard-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, dramesh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org List-Id: linux-tegra@vger.kernel.org On 1/22/2020 11:53 AM, Dmitry Osipenko wrote: > External email: Use caution opening links or attachments > > > 22.01.2020 07:32, Sameer Pujar =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > [snip] >>>>>> +static int tegra210_i2s_remove(struct platform_device *pdev) >>>>>> +{ >>>>>> + pm_runtime_disable(&pdev->dev); >>>>>> + if (!pm_runtime_status_suspended(&pdev->dev)) >>>>>> + tegra210_i2s_runtime_suspend(&pdev->dev); >>>>> This breaks device's RPM refcounting if it was disabled in the active >>>>> state. This code should be removed. At most you could warn about the >>>>> unxpected RPM state here, but it shouldn't be necessary. >>>> I guess this was added for safety and explicit suspend keeps clock >>>> disabled. >>>> Not sure if ref-counting of the device matters when runtime PM is >>>> disabled and device is removed. >>>> I see few drivers using this way. >>> It should matter (if I'm not missing something) because RPM should be i= n >>> a wrecked state once you'll try to re-load the driver's module. Likely >>> that those few other drivers are wrong. >>> >>> [snip] >> Once the driver is re-loaded and RPM is enabled, I don't think it would = use >> the same 'dev' and the corresponding ref count. Doesn't it use the new >> counters? >> If RPM is not working for some reason, most likely it would be the case >> for other >> devices. What best driver can do is probably do a force suspend during >> removal if >> already not done. I would prefer to keep, since multiple drivers still >> have it, >> unless there is a real harm in doing so. > I took a closer look and looks like the counter actually should be > reset. Still I don't think that it's a good practice to make changes > underneath of RPM, it may strike back. If RPM is broken, it probably would have been caught during device usage. I will remove explicit suspend here if no any concerns from other folks.=20 Thanks. > >>>>>> + int rx_fifo_th; >>>>> Could rx_fifo_th be negative? >>>> rx_fifo_th itself does not take negative values, explicit >>>> typecasting> is avoided in "if" condition by declaring this as "int" >>> Explicit typecasting isn't needed for integers. >> What I meant was, rx_fifo_th is checked against a 'int' variable in an >> "if" condition. > What's the problem with comparing of unsigned with signed? consider this example, ---- unsigned int x =3D 5; int y =3D -1; (x > y) is false. ---- Hence should be careful while using signed and unsigned comparisons. > > Besides, cif_conf.audio_ch > I2S_RX_FIFO_DEPTH can't be ever true, isn't > it? I2S_RX_FIFO_DEPTH=3D64, channels_max=3D16 Yes true. > Lastly, nothing stops you to make max_th unsigned. will update.