From: Hans de Goede <hdegoede@redhat.com>
To: Wolfram Sang <wsa@the-dreams.de>
Cc: linux-samsung-soc@vger.kernel.org, linux-pm@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
Wolfram Sang <wsa+renesas@sang-engineering.com>,
bcm-kernel-feedback-list@broadcom.com, linux-i2c@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC/RFT 00/10] i2c: move handling of suspended adapters to the core
Date: Tue, 18 Dec 2018 22:44:38 +0100 [thread overview]
Message-ID: <0e6b0ea6-e472-19f2-bb2f-61a1d66e6091@redhat.com> (raw)
In-Reply-To: <20181218201725.2uqfmsethlkasdvc@ninjato>
Hi,
On 18-12-18 21:17, Wolfram Sang wrote:
> Hans, all,
>
>>> ... this. I don't know what these flags do (and reading SMART in there
>>> gives me more a 'uh-oh' feeling)
>>
>> On x86 the lines between runtime suspend and system-suspend are blurring
>> with technologies like "connected standby" and in general devices moving
>> to suspend2idle as system-suspend state, I guess this also applies to
>> modern smartphone platforms but I'm not following those closely.
>
> I'd guess so, too. I am not aware of any existing mechanism for that at
> the moment, though. If somebody does, please enlighten us.
>
>> The "SMART" bit is really not all that smart, SMART_PREPARE means that
>> the drivers pm prepare callback will return positive non 0 (e.g. 1) to
>> indicate that the device may not be kept in its runtime suspended
>> state when transitioning to system-suspend, otoh when the prepare
>> callback returns 0 and the SMART_PREPARE flag is set then *all* suspend/
>> resume handling can be skipped during a system suspend.
>
> Thanks for the detailed explanation! Much appreciated.
>
>>> Looking at the open coded version you did for the designware driver, I
>>> wonder now if it is better to just leave it at driver level? Need to
>>> sleep over it, though.
>>
>> I myself was thinking in the same direction (leave the entire suspended
>> check at the driver level).
>
> So, I was giving it some more thoughts, and my feeling is to still apply
> this series with the review comments addressed. Plus, clearly mark the
> new 'is_suspended' flag and the helper function as *optional* to allow
> for driver specific solutions as well. The then-to-be-added
> documentation would state that it is mostly useful for seperated system
> suspend and runtime suspend. For more complex situations, custom
> solutions are accepted, too. Which means your patch for designware
> should be added to the series.
>
> My take is there are enough drivers out there already which can benefit
> from this new helper. If it turns out to be useless somewhen in the
> future, we can still remove it.
>
> What do you (and all others, of course) think?
I've been thinking along the same lines: your series for the drivers
with separate runtime and system suspend handlers, "custom" driver
specific code for troublesome cases like i2c-designware.
Do you want me to send out a new version of my patch for the i2c-designware
code?
Regards,
Hans
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next prev parent reply other threads:[~2018-12-18 21:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-10 21:02 [RFC/RFT 00/10] i2c: move handling of suspended adapters to the core Wolfram Sang
2018-12-10 21:02 ` [RFC/RFT 01/10] i2c: add 'is_suspended' flag for i2c adapters Wolfram Sang
2018-12-10 22:03 ` Peter Rosin
2018-12-18 23:33 ` Wolfram Sang
2018-12-19 9:39 ` Geert Uytterhoeven
2018-12-19 16:31 ` Wolfram Sang
2018-12-10 21:03 ` [RFC/RFT 02/10] i2c: reject new transfers when adapters are suspended Wolfram Sang
2018-12-10 21:03 ` [RFC/RFT 03/10] i2c: synquacer: remove unused is_suspended flag Wolfram Sang
2018-12-10 21:04 ` Ard Biesheuvel
2018-12-10 21:03 ` [RFC/RFT 04/10] i2c: brcmstb: use core helper to mark adapter suspended Wolfram Sang
2018-12-11 16:44 ` Kamal Dasu
2018-12-10 21:03 ` [RFC/RFT 05/10] i2c: zx2967: " Wolfram Sang
2018-12-11 2:12 ` Shawn Guo
2018-12-10 21:03 ` [RFC/RFT 06/10] i2c: sprd: don't use pdev as variable name for struct device * Wolfram Sang
2018-12-10 21:03 ` [RFC/RFT 07/10] i2c: sprd: use core helper to mark adapter suspended Wolfram Sang
2018-12-10 21:03 ` [RFC/RFT 08/10] i2c: exynos5: " Wolfram Sang
2018-12-18 11:23 ` Marek Szyprowski
2018-12-18 19:52 ` Wolfram Sang
2018-12-10 21:03 ` [RFC/RFT 09/10] i2c: s3c2410: " Wolfram Sang
2018-12-18 11:24 ` Marek Szyprowski
2018-12-10 21:03 ` [RFC/RFT 10/10] i2c: rcar: add suspend/resume support Wolfram Sang
2018-12-10 21:52 ` Peter Rosin
2018-12-18 23:47 ` Wolfram Sang
2018-12-11 19:24 ` [RFC/RFT 00/10] i2c: move handling of suspended adapters to the core Hans de Goede
2018-12-11 23:41 ` Wolfram Sang
2018-12-12 10:09 ` Hans de Goede
2018-12-18 20:17 ` Wolfram Sang
2018-12-18 21:44 ` Hans de Goede [this message]
2018-12-18 23:32 ` Wolfram Sang
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