linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Thorsten Leemhuis <regressions@leemhuis.info>
To: Will Deacon <will@kernel.org>
Cc: Amit Pundir <amit.pundir@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Sibi Sankar <quic_sibis@quicinc.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
	Robin Murphy <robin.murphy@arm.com>,
	andersson@kernel.org, sumit.semwal@linaro.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, hch@lst.de,
	gregkh@linuxfoundation.org
Subject: Re: [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()"
Date: Fri, 2 Dec 2022 11:34:30 +0100	[thread overview]
Message-ID: <92a148a3-a8ac-4065-123c-99b72ac3ebeb@leemhuis.info> (raw)
In-Reply-To: <20221202100357.GB29396@willie-the-truck>

On 02.12.22 11:03, Will Deacon wrote:
> On Fri, Dec 02, 2022 at 09:54:05AM +0100, Thorsten Leemhuis wrote:
>> On 02.12.22 09:26, Amit Pundir wrote:
>>> On Thu, 1 Dec 2022 at 23:15, Catalin Marinas <catalin.marinas@arm.com> wrote:
>>>>
>>>> On Thu, Dec 01, 2022 at 10:29:39AM +0100, Thorsten Leemhuis wrote:
>>>>> Has any progress been made to fix this regression? It afaics is not a
>>>>> release critical issue, but well, it still would be nice to get this
>>>>> fixed before 6.1 is released.
>>>>
>>>> The only (nearly) risk-free "fix" for 6.1 would be to revert the commit
>>>> that exposed the driver bug. It doesn't fix the actual bug, it only
>>>> makes it less likely to happen.
>>>>
>>>> I like the original commit removing the cache invalidation as it shows
>>>> drivers not behaving properly
>>
>> Yeah, I understand that, but I guess it's my job to ask at this point:
>> "is continuing to live with the old behavior for one or two more cycles"
>> that much of a problem"?
> 
> That wouldn't be a problem. The problem is that I haven't see any efforts
> from the Qualcomm side to actually fix the drivers [...]

Thx for sharing the details. I can fully understand your pain. But well,
in the end it looks to me like this commit it intentionally breaking
something that used to work -- which to my understanding of the "no
regression rule" is not okay, even if things only worked by chance and
not flawless.

But well, as with every rule there are misunderstandings, grey areas,
and situations where judgement calls have to be made. Then it's up to
Linus to decide how to handle things. Hence I'll just point him to this
thread and then he can decide. No biggie. And sorry if I'm being a PITA
here, I just thing doing that is my duty as regression tracker in
situations like this. Hope your won't mind.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)

P.S.: As the Linux kernel's regression tracker I deal with a lot of
reports and sometimes miss something important when writing mails like
this. If that's the case here, don't hesitate to tell me in a public
reply, it's in everyone's interest to set the public record straight.

  reply	other threads:[~2022-12-02 10:35 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-14 11:03 [PATCH] Revert "arm64: dma: Drop cache invalidation from arch_dma_prep_coherent()" Manivannan Sadhasivam
2022-11-14 11:29 ` Manivannan Sadhasivam
2022-11-14 14:11 ` Will Deacon
2022-11-14 15:14   ` Robin Murphy
2022-11-14 17:38     ` Catalin Marinas
2022-11-18 10:54       ` Manivannan Sadhasivam
2022-11-18 12:33         ` Will Deacon
2022-11-21  6:42           ` Manivannan Sadhasivam
2022-11-21 10:12             ` Sibi Sankar
2022-11-24 11:55               ` Catalin Marinas
2022-12-01  9:29                 ` Thorsten Leemhuis
2022-12-01 17:45                   ` Catalin Marinas
2022-12-02  8:26                     ` Amit Pundir
2022-12-02  8:54                       ` Thorsten Leemhuis
2022-12-02 10:03                         ` Will Deacon
2022-12-02 10:34                           ` Thorsten Leemhuis [this message]
2022-12-02 16:10                             ` Greg KH
2022-12-02 16:27                               ` Thorsten Leemhuis
2022-12-02 16:32                                 ` Greg KH
2022-12-02 17:14                                   ` Manivannan Sadhasivam
2022-12-05 14:24                                     ` Will Deacon
2022-12-06  9:21                                       ` Manivannan Sadhasivam
2022-12-06  9:58                                         ` Will Deacon
2022-12-02 10:54                           ` Manivannan Sadhasivam
2022-11-28  5:44 ` Thorsten Leemhuis
2022-11-28  8:15   ` Manivannan Sadhasivam
2022-12-08  4:59 ` Leonard Lausen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=92a148a3-a8ac-4065-123c-99b72ac3ebeb@leemhuis.info \
    --to=regressions@leemhuis.info \
    --cc=amit.pundir@linaro.org \
    --cc=andersson@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@lst.de \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=manivannan.sadhasivam@linaro.org \
    --cc=quic_sibis@quicinc.com \
    --cc=robin.murphy@arm.com \
    --cc=sumit.semwal@linaro.org \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).