linux-kernel - Re: [PATCH 1/3] drm/msm/dp: account for widebus in msm_dp_catalog_panel_tpg

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Message-ID: <6d9aea46-b18b-4bc2-86f6-0805258cc3c4@quicinc.com>
Date: Tue, 3 Dec 2024 11:48:59 -0800
From: Abhinav Kumar <quic_abhinavk@...cinc.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
CC: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        "Marijn
 Suijten" <marijn.suijten@...ainline.org>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Stephen Boyd <swboyd@...omium.org>,
        "Kuogee
 Hsieh" <quic_khsieh@...cinc.com>,
        <linux-arm-msm@...r.kernel.org>, <dri-devel@...ts.freedesktop.org>,
        <freedreno@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        Jessica Zhang <quic_jesszhan@...cinc.com>
Subject: Re: [PATCH 1/3] drm/msm/dp: account for widebus in
 msm_dp_catalog_panel_tpg_enable()



On 12/3/2024 6:34 AM, Dmitry Baryshkov wrote:
> On Mon, Dec 02, 2024 at 12:41:58PM -0800, Abhinav Kumar wrote:
>> Adjust the h_active calculation to account for widebus in tpg.
>>
>> Fixes: 757a2f36ab09 ("drm/msm/dp: enable widebus feature for display port")
>> Signed-off-by: Abhinav Kumar <quic_abhinavk@...cinc.com>
>> ---
>>   drivers/gpu/drm/msm/dp/dp_catalog.c | 14 +++++++++++++-
>>   1 file changed, 13 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/msm/dp/dp_catalog.c b/drivers/gpu/drm/msm/dp/dp_catalog.c
>> index b4c8856fb25d..05c8e1996f60 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_catalog.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_catalog.c
>> @@ -1011,9 +1011,21 @@ void msm_dp_catalog_panel_tpg_enable(struct msm_dp_catalog *msm_dp_catalog,
>>   	u32 v_sync_width;
>>   	u32 hsync_ctl;
>>   	u32 display_hctl;
>> +	u32 h_sync_width;
>> +	u32 h_front_porch;
>> +	u32 h_back_porch;
>> +	u32 h_active;
>> +
>> +	h_active = drm_mode->hdisplay;
>> +	h_back_porch = drm_mode->htotal - drm_mode->hsync_end;
>> +	h_sync_width = drm_mode->htotal - (drm_mode->hsync_start + h_back_porch);
> 
> It's at least drm_mode->hsync_end - drm_mode->hsync_start
> 
>> +	h_front_porch = drm_mode->hsync_start - drm_mode->hdisplay;
>> +
>> +	if (msm_dp_catalog->wide_bus_en)
>> +		h_active /= 2;
>>   
>>   	/* TPG config parameters*/
>> -	hsync_period = drm_mode->htotal;
>> +	hsync_period = h_sync_width + h_back_porch + h_active + h_front_porch;
> 
> Is it equivalent to:
> 
> hsync_period = drm_mode->htotal;
> if (msm_dp_catalog->wide_bus_en)
>      hsync_period -= drm_mode->hdisplay / 2;
> 
> I think it's simpler to handle.
> 

Yes certainly!

Thanks for the feedback. Will fix it up.

>>   	vsync_period = drm_mode->vtotal;
>>   
>>   	display_v_start = ((drm_mode->vtotal - drm_mode->vsync_start) *
>>
>> -- 
>> 2.34.1
>>
>