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Date:   Fri, 14 Apr 2023 17:02:34 -0700
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Subject: Re: [PATCH v2] drm/msm/dpu: always program dsc active bits
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To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
CC:     Marijn Suijten <marijn.suijten@somainline.org>,
        Kuogee Hsieh <quic_khsieh@quicinc.com>, <robdclark@gmail.com>,
        <sean@poorly.run>, <swboyd@chromium.org>, <dianders@chromium.org>,
        <vkoul@kernel.org>, <daniel@ffwll.ch>, <airlied@gmail.com>,
        <agross@kernel.org>, <andersson@kernel.org>,
        <quic_sbillaka@quicinc.com>, <freedreno@lists.freedesktop.org>,
        <dri-devel@lists.freedesktop.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
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From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <CAA8EJpoOZOwLfa4tx1zhp8w5cY+3OR4J4o0xjTaNO5SMM=F6Bg@mail.gmail.com>
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On 4/14/2023 3:53 PM, Dmitry Baryshkov wrote:
> On Sat, 15 Apr 2023 at 00:03, Abhinav Kumar <quic_abhinavk@quicinc.com> wrote:
>>
>>
>>
>> On 4/14/2023 1:58 PM, Dmitry Baryshkov wrote:
>>> On Fri, 14 Apr 2023 at 21:55, Abhinav Kumar <quic_abhinavk@quicinc.com> wrote:
>>>>
>>>>
>>>>
>>>> On 4/14/2023 10:28 AM, Marijn Suijten wrote:
>>>>> On 2023-04-14 08:41:37, Abhinav Kumar wrote:
>>>>>>
>>>>>> On 4/14/2023 12:48 AM, Marijn Suijten wrote:
>>>>>>> Capitalize DSC in the title, as discussed in v1.
>>>>>>>
>>>>>>> On 2023-04-13 08:56:41, Kuogee Hsieh wrote:
>>>>>>>> In current code, the DSC active bits are written only if cfg->dsc is set.
>>>>>>>> However, for displays which are hot-pluggable, there can be a use-case
>>>>>>>> of disconnecting a DSC supported sink and connecting a non-DSC sink.
>>>>>>>>
>>>>>>>> For those cases we need to clear DSC active bits during tear down.
>>>>>>>>
>>>>>>>> Changes in V2:
>>>>>>>> 1) correct commit text as suggested
>>>>>>>> 2) correct Fixes commit id
>>>>>>>> 3) add FIXME comment
>>>>>>>>
>>>>>>>> Fixes: 77f6da90487c ("drm/msm/disp/dpu1: Add DSC support in hw_ctl")
>>>>>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
>>>>>>>> Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>
>>>>>>>
>>>>>>> By default git send-email should pick this up in the CC line...  but I
>>>>>>> had to download this patch from lore once again.
>>>>>>>
>>>>>>
>>>>>> Yes, I think what happened here is, he didnt git am the prev rev and
>>>>>> make changes on top of that so git send-email didnt pick up. We should
>>>>>> fix that process.
>>>>>
>>>>> The mail was sent so it must have gone through git send-email, unless a
>>>>> different mail client was used to send the .patch file.  I think you are
>>>>> confusing this with git am (which doesn't need to be used if editing a
>>>>> commit on a local branch) and subsequently git format-patch, which takes
>>>>> a commit from a git repository and turns it into a .patch file: neither
>>>>> of these "converts" r-b's (and other tags) to cc, that's happening in
>>>>> git send-email (see `--suppress-cc` documentation in `man
>>>>> git-send-email`).
>>>>>
>>>>
>>>> Yes, ofcourse git send-email was used to send the patch, not any other
>>>> mail client.
>>>>
>>>> Yes i am also aware that send-email converts rb to CC.
>>>>
>>>> But if you keep working on the local branch, then you would have to
>>>> manually add the r-bs. If you use am of the prev version and develop on
>>>> that, it will automatically add the r-bs.
>>>
>>> It looks like there is some misunderstanding here. I think Marijn
>>> doesn't question his R-B (which was present), but tries to point out
>>> that Kuogee might want to adjust his git-send-email invocation. By
>>> default (and that's a good practice, which we should follow),
>>> git-send-email will CC people mentioned in such tags. Marijn didn't
>>> get this email. So, it seems, for some reason this Cc: _mail_ header
>>> was suppressed. Probably git-send-email invocation should be changed
>>> to prevent suppression of adding mentioned people to CC lists.
>>>
>>
>> Yeah I understood that part. There were two issues here:
>>
>> 1) My r-b got dropped and that was because am wasn't used to
>> automatically retain tags from prev version.
>>
>> If you dont add the r-bs either manually or by am, then folks wont be
>> part of CC either
> 
> Just as a note: there is nothing wrong with adding tags manually. I do
> that for some of my patchsets (and sometimes I miss them too).
> 

Nothing wrong, especially when sometimes its given on IRC or something, 
I have to add it manually that time too.

But, just prone to forgetting. Like this case.

Next time, lets say Marijn again gives R-b, but someone else forgets to 
manually apply it, the same issue will happen even if proper git 
send-email is used.

>>
>> 2) I synced with kuogee. his git version seems to be quite old which is
>> not adding the folks from r-b to cc. So there was nothing wrong with
>> invocation, just versioning.
> 
> Ack. Thanks for updating it.
> 
>>
>>
>>>>
>>>>
>>>>> I can recommend b4: it has lots of useful features including
>>>>> automatically picking up reviews and processing revisions.  It even
>>>>> requires a changelog to be edited ;).  However, finding the right flags
>>>>> and trusting it'll "do as ordered" is a bit daunting at first.
>>>>>
>>>>>>>> ---
>>>>>>>>      drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c | 8 ++++----
>>>>>>>>      1 file changed, 4 insertions(+), 4 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>>>>>>>> index bbdc95c..1651cd7 100644
>>>>>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>>>>>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c
>>>>>>>> @@ -541,10 +541,10 @@ static void dpu_hw_ctl_intf_cfg_v1(struct dpu_hw_ctl *ctx,
>>>>>>>>              if (cfg->merge_3d)
>>>>>>>>                      DPU_REG_WRITE(c, CTL_MERGE_3D_ACTIVE,
>>>>>>>>                                    BIT(cfg->merge_3d - MERGE_3D_0));
>>>>>>>> -  if (cfg->dsc) {
>>>>>>>> -          DPU_REG_WRITE(&ctx->hw, CTL_FLUSH, DSC_IDX);
>>>>>>>> -          DPU_REG_WRITE(c, CTL_DSC_ACTIVE, cfg->dsc);
>>>>>>>> -  }
>>>>>>>> +
>>>>>>>> +  /* FIXME: fix reset_intf_cfg to handle teardown of dsc */
>>>>>>>
>>>>>>> There's more wrong than just moving (not "fix"ing) this bit of code into
>>>>>>> reset_intf_cfg.  And this will have to be re-wrapped in `if (cfg->dsc)`
>>>>>>> again by reverting this patch.  Perhaps that can be explained, or link
>>>>>>> to Abhinav's explanation to make it clear to readers what this FIXME
>>>>>>> actually means?  Let's wait for Abhinav and Dmitry to confirm the
>>>>>>> desired communication here.
>>>>>>>
>>>>>>> https://lore.kernel.org/linux-arm-msm/ec045d6b-4ffd-0f8c-4011-8db45edc6978@quicinc.com/
>>>>>>>
>>>>>>
>>>>>> Yes, I am fine with linking this explanation in the commit text and
>>>>>> mentioning that till thats fixed, we need to go with this solution. The
>>>>>> FIXME itself is fine, I will work on it and I remember this context well.
>>>>>
>>>>> Looks like it was removed entirely in v3, in favour of only describing
>>>>> it in the patch body.  The wording seems a bit off but that's fine by me
>>>>> if you're picking this up soon anyway.
>>>>>
>>>>> - Marijn
>>>
>>>
>>>
> 
> 
>