linux-kernel - Re: [PATCH v2 1/4] drm/msm/dp: Add basic PSR support for eDP

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Message-ID: <490deb0b-aecb-c4a8-ea02-2c687a8da57b@linaro.org>
Date:   Wed, 23 Feb 2022 00:52:50 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Vinod Polimera <quic_vpolimer@...cinc.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        freedreno <freedreno@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Rob Clark <robdclark@...il.com>,
        Sean Paul <seanpaul@...omium.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, quic_kalyant@...cinc.com,
        Sankeerth Billakanti <quic_sbillaka@...cinc.com>,
        quic_vproddut@...cinc.com
Subject: Re: [PATCH v2 1/4] drm/msm/dp: Add basic PSR support for eDP

On 23/02/2022 00:32, Doug Anderson wrote:
> Hi,
> 
> On Tue, Feb 22, 2022 at 1:23 PM Dmitry Baryshkov
> <dmitry.baryshkov@...aro.org> wrote:
>>
>> On 22/02/2022 22:25, Doug Anderson wrote:
>>> Hi,
>>>
>>> On Mon, Feb 21, 2022 at 7:12 PM Dmitry Baryshkov
>>> <dmitry.baryshkov@...aro.org> wrote:
>>>>
>>>>> +static int dp_link_psr_status(struct dp_link_private *link)
>>>>> +{
>>>>> +       u8 status[2];
>>>>> +
>>>>> +       drm_dp_dpcd_read(link->aux, DP_PSR_ERROR_STATUS, status, 2);
>>>>> +
>>>>> +       if (status[0] & DP_PSR_LINK_CRC_ERROR)
>>>>> +               DRM_ERROR("PSR LINK CRC ERROR\n");
>>>>> +       else if (status[0] & DP_PSR_RFB_STORAGE_ERROR)
>>>>> +               DRM_ERROR("PSR RFB STORAGE ERROR\n");
>>>>> +       else if (status[0] & DP_PSR_VSC_SDP_UNCORRECTABLE_ERROR)
>>>>> +               DRM_ERROR("PSR VSC SDP UNCORRECTABLE ERROR\n");
>>>>> +       else if (status[1] & DP_PSR_CAPS_CHANGE)
>>>>> +               DRM_INFO("PSR Capability Change\n");
>>>>
>>>> DRM_DEBUG_DP
>>>
>>> Not sure I'll have time to go back and review the series, but one
>>> thing that caught my eye as this flashed through my inbox is that I
>>> think all of these "shouting" are deprecated. It's even officially
>>> documented now as of commit d2f0a8afc1be ("UPSTREAM: drm/print: Add
>>> deprecation notes to DRM_...() functions").
>>
>> Agreed. But not the DRM_INFO too.
> 
> You're saying that DRM_INFO _isn't_ deprecated? I was pretty sure that
> it was, too. If not, can you please submit a patch to `drm_print.h`
> clarifying since my patch (which folks Acked) marked it as deprecated:

It is deprecated

> My understanding (also in the description of my patch) was that
> DRM_INFO() by itself didn't add much so we should just use the
> standard pr_info(). If pr_info() wasn't to your liking then it was
> better to do drm_info(drmdev, ...) or drm_info(NULL, ...);

I don't think we should get this message at all, unless debugging is 
enabled. Thus I asked to change DRM_INFO to DEBUG.

Regarding your point, I'm fine with either of them. Hopefully when 
Kuogee's patches are in, we can use drm_dbg_db w/o any issues.

-- 
With best wishes
Dmitry