linux-kernel - Re: [PATCH v2 3/3] ata: ahci: Skip 200 ms debounce delay for AMD 300 Series Chipset SATA Controller

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Message-ID: <67950993-2eb9-c180-7c80-98c9954c9b22@molgen.mpg.de>
Date:   Fri, 1 Apr 2022 07:18:43 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Damien Le Moal <damien.lemoal@...nsource.wdc.com>
Cc:     Mario Limonciello <Mario.Limonciello@....com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-ide@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Nehal-bakulchandra Shah <Nehal-bakulchandra.Shah@....com>
Subject: Re: [PATCH v2 3/3] ata: ahci: Skip 200 ms debounce delay for AMD 300
 Series Chipset SATA Controller

Dear Damien,


Thank you for your reply.


Am 01.04.22 um 01:04 schrieb Damien Le Moal:
> On 3/31/22 23:42, Paul Menzel wrote:

>> Am 23.03.22 um 09:36 schrieb Paul Menzel:
>>
>>> Am 23.03.22 um 09:24 schrieb Damien Le Moal:
>>>> On 3/23/22 15:55, Paul Menzel wrote:
>>>
>>>>> Am 23.03.22 um 06:01 schrieb Damien Le Moal:
>>>>>> On 3/22/22 06:51, Limonciello, Mario wrote:
>>>
>>>>>>>> -----Original Message-----
>>>>>>>> From: Paul Menzel <pmenzel@...gen.mpg.de>
>>>>>>>> Sent: Monday, March 21, 2022 16:25
>>>>>
>>>>> […]
>>>>>
>>>>>>> I seem to recall that we were talking about trying to drop the
>>>>>>> debounce delay for everything, weren't we?
>>>>>>>
>>>>>>> So perhaps it would be right to add a 4th patch in the series to do
>>>>>>> just that.  Then If this turns out to be problematic for
>>>>>>> anything other than the controllers in the series that you
>>>>>>> identified as not problematic then that 4th patch can
>>>>>>> potentially be reverted alone?
>>>>>>
>>>>>> Not quite everything :) But you are right, let's try to switch the
>>>>>> default to no delay. I will be posting patches today for that.
>>>>>> With these patches, your patches are not necessary anymore as the AMD
>>>>>> chipset falls under the default no-delay.
>>>>>
>>>>> I am all for improving the situation for all devices, but I am unable to
>>>>> judge the regression potential of changing this, as it affects a lot of
>>>>> devices. I guess it’d would go through the next tree, and hopefully the
>>>>> company QA teams can give it a good spin. I hoped that my patches, as I
>>>>> have tested them, and AMD will hopefully too, could go into the current
>>>>> merge window.
>>>>
>>>> Yes, correct, the plan is to get the generic series queued as soon
>>>> as rc1 so that it can spend plenty of time in linux-next for people
>>>> to test. That will hopefully reduce the risk of breaking things in
>>>> the field. Same for  the default LPM change.
>>>
>>> But 5.18 or 5.19? If 5.18, sounds good to me, if 5.19, I’d be great if
>>> my patches go into 5.18 cycle, as they have been tested, and it would
>>> mean the whole change gets tested more widely already.
>>>
>>>> With the default removal of the debounce delay, your patches addressing
>>>> only the AMD adapter are not needed anymore: this adapter will not have a
>>>> debounce delay unless the ATA_LFLAG_DEBOUNCE_DELAY flag is set.
>>>
>>> Yes, I understand.
>>
>> The merge window for Linux 5.18 is going to close in three days this
>> Sunday. It’d be really great if my patches, tested on hardware, could go
>> into that.
>>
>>>>>> It would be nice if you can test though.
>>>>>
>>>>> Of course, I am going to that either way.
>>>>
>>>> Series posted with you on CC. Please test !
>>>
>>> Thank you. I am going to test it in the coming days, and report back.
>>>
>>> Maybe more people should be put in Cc (Dell, Lenovo, IBM, x86 subsystem)
>>> with a request to test this?
>> Thank you for the patches, which are a big improvement. Let’s hope, you
>> can re-roll them, so they get into Linux very soon for everyone’s benefit.
> 
> I am waiting for 5.18-rc1 to rebase the patches and re-post them. Given
> reviewed-by and tested-by tags, I will queue them for 5.19.

As discussed in the other thread, it’s impossible to be 100 % certain, 
it won’t break anything.

> With that in mind, I am not planning to apply your previous patches
> for 5.18, as they would conflict and would only end up being churn
> since the delay removal by default will undo your changes.
Obviously, I do not agree, as this would give the a little bit more 
testing already, if changing the default is a good idea. Also, if the 
conflict will be hard to resolve, I happily do it (the patches could 
even be reverted on top – git commits are cheap and easy to handle).

Anyway, I wrote my piece, but you are the maintainer, so it’s your call 
and I stop bothering you.


Kind regards,

Paul