linux-kernel - Re: [PATCH 6/8] drm/msm/dp: Add maximum width limitation for modes

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Message-ID: <3e7660b3-934a-4b11-82a3-48137d63ea5d@quicinc.com>
Date: Fri, 6 Dec 2024 12:13:23 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Xiangxu Yin
	<quic_xiangxuy@...cinc.com>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        "Marijn
 Suijten" <marijn.suijten@...ainline.org>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Rob Herring <robh@...nel.org>,
        "Krzysztof
 Kozlowski" <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        "Kuogee
 Hsieh" <quic_khsieh@...cinc.com>,
        Vinod Koul <vkoul@...nel.org>,
        "Kishon
 Vijay Abraham I" <kishon@...nel.org>,
        Linus Walleij
	<linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>, <quic_lliu6@...cinc.com>,
        <quic_fangez@...cinc.com>, <linux-arm-msm@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <freedreno@...ts.freedesktop.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-phy@...ts.infradead.org>, <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH 6/8] drm/msm/dp: Add maximum width limitation for modes



On 12/3/2024 5:58 AM, Dmitry Baryshkov wrote:
> On Tue, Dec 03, 2024 at 03:41:53PM +0800, Xiangxu Yin wrote:
>>
>>
>> On 12/2/2024 5:32 PM, Dmitry Baryshkov wrote:
>>> On Mon, 2 Dec 2024 at 11:05, Xiangxu Yin <quic_xiangxuy@...cinc.com> wrote:
>>>>
>>>>
>>>>
>>>> On 11/29/2024 9:52 PM, Dmitry Baryshkov wrote:
>>>>> On Fri, 29 Nov 2024 at 09:59, Xiangxu Yin <quic_xiangxuy@...cinc.com> wrote:
>>>>>>
>>>>>> Introduce a maximum width constraint for modes during validation. This
>>>>>> ensures that the modes are filtered based on hardware capabilities,
>>>>>> specifically addressing the line buffer limitations of individual pipes.
>>>>>
>>>>> This doesn't describe, why this is necessary. What does "buffer
>>>>> limitations of individual pipes" mean?
>>>>> If the platforms have hw capabilities like being unable to support 8k
>>>>> or 10k, it should go to platform data
>>>>>
>>>> It's SSPP line buffer limitation for this platform and only support to 2160 mode width.
>>>> Then, shall I add max_width config to struct msm_dp_desc in next patch? for other platform will set defualt value to ‘DP_MAX_WIDTH 7680'
>>>
>>> SSPP line buffer limitations are to be handled in the DPU driver. The
>>> DP driver shouldn't care about those.
>>>
>> Ok, Will drop this part in next patch.
> 
> If you drop it, what will be left from the patch itself?
> 

Yes agree with Dmitry, max_width is really not a DP related terminology.

This patch should be dropped.

So there were two issues, overall in this series causing this patch:

1) In https://patchwork.freedesktop.org/patch/625822/, instead of using 
VIG_SDM845_MASK, we should be using VIG_SDM845_MASK_SDMA. Without that 
even 2k will not work, will leave a comment there.

2) 4k will still fail. I dont think we can even support 4k on QCS615 but 
the modes should be filtered out because there is no 3dmux.

I have submitted https://patchwork.freedesktop.org/patch/627694/ to 
address this.

Xiangxu, please let me know if that works for you.

Thanks

Abhinav
>>>>>>
>>>>>> Signed-off-by: Xiangxu Yin <quic_xiangxuy@...cinc.com>
>>>>>> ---
>>>>>>   drivers/gpu/drm/msm/dp/dp_display.c |  3 +++
>>>>>>   drivers/gpu/drm/msm/dp/dp_display.h |  1 +
>>>>>>   drivers/gpu/drm/msm/dp/dp_panel.c   | 13 +++++++++++++
>>>>>>   drivers/gpu/drm/msm/dp/dp_panel.h   |  1 +
>>>>>>   4 files changed, 18 insertions(+)
>>>
>>>
>>
>