linux-kernel - Re: [PATCH RFC 06/10] drm/panel/samsung-sofef01: Add panel driver for Sony Xperia 5 / 10 II

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Date:   Tue, 30 May 2023 01:20:17 +0300
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Marijn Suijten <marijn.suijten@...ainline.org>
Cc:     Neil Armstrong <neil.armstrong@...aro.org>,
        Sam Ravnborg <sam@...nborg.org>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Caleb Connolly <caleb@...nolly.tech>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        ~postmarketos/upstreaming@...ts.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>,
        Jessica Zhang <quic_jesszhan@...cinc.com>
Subject: Re: [PATCH RFC 06/10] drm/panel/samsung-sofef01: Add panel driver for
 Sony Xperia 5 / 10 II

On 29/05/2023 23:58, Marijn Suijten wrote:
> On 2023-05-23 01:56:46, Dmitry Baryshkov wrote:
>> On Tue, 23 May 2023 at 01:32, Marijn Suijten
>> <marijn.suijten@...ainline.org> wrote:
>>>
>>> On 2023-05-22 04:19:45, Dmitry Baryshkov wrote:
>>>> On 22/05/2023 00:23, Marijn Suijten wrote:
>>>>> This SOFEF01-M Display-IC driver supports two modes with different
>>>>> compatibles to differentiate between slightly different physical sizes
>>>>> (panels) found on the Xperia 5 (6.1") and 10 II (6.0").
>>>>>
>>>>> It is currently also used to hardcode significantly higher fake porches
>>>>> for the Xperia 5, which are unused in transfers due to this being a
>>>>> command-mode panel but do have an effect on the clock rates set by
>>>>> dsi_host.c.  Without higher clock rates this panel fails to achieve
>>>>> 60fps and has significant tearing artifacts, while the same calculated
>>>>> clock rate works perfectly fine on the Xperia 10 II.
>>>
>>> <snip>
>>>
>>>>> +/* Sony Xperia 5 (kumano bahamut) */
>>>>> +static const struct drm_display_mode samsung_sofef01_m_bahamut_mode = {
>>>>> +   /*
>>>>> +    * WARNING: These massive porches are wrong/useless for CMDmode
>>>>> +    * (and not defined in downstream DTS) but necessary to bump dsi
>>>>> +    * clocks higher, so that we can achieve proper 60fps without tearing.
>>>>> +    */
>>>>> +   .clock = (1080 + 156 + 8 + 8) * (2520 + 2393 + 8 + 8) * 60 / 1000,
>>>>> +   .hdisplay = 1080,
>>>>> +   .hsync_start = 1080 + 156,
>>>>> +   .hsync_end = 1080 + 156 + 8,
>>>>> +   .htotal = 1080 + 156 + 8 + 8,
>>>>> +   .vdisplay = 2520,
>>>>> +   .vsync_start = 2520 + 2393,
>>>>> +   .vsync_end = 2520 + 2393 + 8,
>>>>> +   .vtotal = 2520 + 2393 + 8 + 8,
>>>>> +   .width_mm = 61,
>>>>> +   .height_mm = 142,
>>>>> +};
>>>>> +
>>>>> +/* Sony Xperia 10 II (seine pdx201) */
>>>>> +static const struct drm_display_mode samsung_sofef01_m_pdx201_mode = {
>>>>> +   .clock = (1080 + 8 + 8 + 8) * (2520 + 8 + 8 + 8) * 60 / 1000,
>>>>> +   .hdisplay = 1080,
>>>>> +   .hsync_start = 1080 + 8,
>>>>> +   .hsync_end = 1080 + 8 + 8,
>>>>> +   .htotal = 1080 + 8 + 8 + 8,
>>>>> +   .vdisplay = 2520,
>>>>> +   .vsync_start = 2520 + 8,
>>>>> +   .vsync_end = 2520 + 8 + 8,
>>>>> +   .vtotal = 2520 + 8 + 8 + 8,
>>>>> +   .width_mm = 60,
>>>>> +   .height_mm = 139,
>>>>> +};
>>>>> +
>>>>> +static const struct of_device_id samsung_sofef01_m_of_match[] = {
>>>>> +   { .compatible = "samsung,sofef01-m-bahamut", .data = &samsung_sofef01_m_bahamut_mode },
>>>>> +   { .compatible = "samsung,sofef01-m-pdx201", .data = &samsung_sofef01_m_pdx201_mode },
>>>>
>>>> Are there really two panels? Can we use one mode for both usecases?
>>>
>>> See the commit description where I explained exactly this: the panels
>>> have different dimensions (6.1" vs 6.0", hence different DPI) and I also
>>> abuse this to hack in higher clock rates via fake porches.
>>>
>>> I just ended up on a scary website that supposedly contains the panel
>>> names:
>>>
>>> - Xperia 5 (bahamut, 6.1"): AMB609TC01
>>> - Xperia 10 II (pdx201, 6.0"): AMS597UT01
>>
>> Great! From the patch description it was not obvious if those are two
>> different panels or a single panel with slight difference in the glass
>> cover. With these names in place (well, with two distinct names in
>> place) it makes sense.
> 
> For completeness: keep the current single file but embed these panel
> names as suffix (eg. `samsung,sofef-01-m-am[bs]...`) to the compatible
> (and document these more explicitly elsewhere)?

Where do the sofef parts of the name come from? Glancing at other 
panels, I'd expect something simpler. Maybe:

samsung,sofef01m-amb60...

> 
> - Marijn
> 
>>
>> -- 
>> With best wishes
>> Dmitry

-- 
With best wishes
Dmitry