Re: [PATCH v2] drm/msm/dpu: always program dsc active bits

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

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

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.


>>
>>
>>> 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
> 
> 
>