linux-kernel - Re: [PATCH v5 00/14] Consolidate and improve NVIDIA Tegra CPUIDLE driver(s)

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Date:   Mon, 30 Sep 2019 21:32:51 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 00/14] Consolidate and improve NVIDIA Tegra CPUIDLE
 driver(s)

30.09.2019 11:26, Thierry Reding пишет:
> On Sun, Sep 29, 2019 at 08:59:38PM +0300, Dmitry Osipenko wrote:
>> Hello,
>>
>> This series does the following:
>>
>>   1. Unifies Tegra20/30/114 drivers into a single driver and moves it out
>>      into common drivers/cpuidle/ directory.
>>
>>   2. Enables CPU cluster power-down idling state on Tegra30.
>>
>> In the end there is a quite nice clean up of the Tegra CPUIDLE drivers
>> and of the Tegra's arch code in general. Please review, thanks!
> 
> I generally like this series and it looks really good from a diffstat
> point of view. However, removing existing drivers completely and then
> incrementally add a new one make this impossible to review.
> 
> If you think about it, it also makes it really difficult to find what
> went wrong if at any point in the future we find a regression caused by
> the new driver. A bisection will always point at the commit that removes
> the old driver because between that and the point where you add the new
> driver, CPU idle just doesn't work at all anymore.
> 
> While I understand that it's very convenient to just throw away old code
> and rewrite it from scratch, it's also impractical (and a little rude).
> It's not how we do things in the kernel. Unless maybe under specific
> circumstances.
> 
> Can you please try and make this a little more iterative? At the very
> least I'd expect a series where you do all the preliminary work in
> preparatory patches and then replace the old driver by the new driver in
> a single patch. That way at least there will be an unambiguous commit in
> a bisection.
> 
> Ideally, you'd also break up that last conversion patch into smaller
> incremental patches to make it easier for people to review. Remember
> that your chances to attract reviewers increases if you make the patches
> easy to review, which means your patches should be small, logical
> changes that (ideally) are obviously correct.

Thanks for the detailed explanation, probably this is the same what Jon
was asking to do. Now I see what you're are asking for.