linux-kernel - Re: [PATCH 1/7] drm/tidss: Add CRTC mode

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Date: Thu, 16 May 2024 16:33:40 +0530
From: Aradhya Bhatia <a-bhatia1@...com>
To: Maxime Ripard <mripard@...nel.org>
CC: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        Andrzej Hajda
	<andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert
 Foss <rfoss@...nel.org>,
        Laurent Pinchart
	<Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej
 Skrabec <jernej.skrabec@...il.com>,
        Maarten Lankhorst
	<maarten.lankhorst@...ux.intel.com>,
        Jyri Sarha <jyri.sarha@....fi>,
        Thomas
 Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>, Daniel
 Vetter <daniel@...ll.ch>,
        DRI Development List
	<dri-devel@...ts.freedesktop.org>,
        Linux Kernel List
	<linux-kernel@...r.kernel.org>,
        Sam Ravnborg <sam@...nborg.org>, Thierry
 Reding <treding@...dia.com>,
        Kieran Bingham
	<kieran.bingham+renesas@...asonboard.com>,
        Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>,
        Praneeth Bajjuri <praneeth@...com>, Udit Kumar <u-kumar1@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jayesh
 Choudhary <j-choudhary@...com>, Jai Luthra <j-luthra@...com>
Subject: Re: [PATCH 1/7] drm/tidss: Add CRTC mode_fixup

Hi Maxime,

Thank you for reviewing the patches.

On 16/05/24 13:40, Maxime Ripard wrote:
> Hi,
> 
> On Sat, May 11, 2024 at 09:00:45PM +0530, Aradhya Bhatia wrote:
>> Add support for mode_fixup for the tidss CRTC.
>>
>> Some bridges like the cdns-dsi consume the crtc_* timing parameters for
>> programming the blanking values. Allow for the normal timing parameters
>> to get copied to crtc_* timing params.
>>
>> Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
>> ---
>>  drivers/gpu/drm/tidss/tidss_crtc.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/tidss/tidss_crtc.c b/drivers/gpu/drm/tidss/tidss_crtc.c
>> index 94f8e3178df5..797ef53d9ad2 100644
>> --- a/drivers/gpu/drm/tidss/tidss_crtc.c
>> +++ b/drivers/gpu/drm/tidss/tidss_crtc.c
>> @@ -309,12 +309,23 @@ enum drm_mode_status tidss_crtc_mode_valid(struct drm_crtc *crtc,
>>  	return dispc_vp_mode_valid(tidss->dispc, tcrtc->hw_videoport, mode);
>>  }
>>  
>> +static
>> +bool tidss_crtc_mode_fixup(struct drm_crtc *crtc,
>> +			   const struct drm_display_mode *mode,
>> +			   struct drm_display_mode *adjusted_mode)
>> +{
>> +	drm_mode_set_crtcinfo(adjusted_mode, 0);
>> +
>> +	return true;
>> +}
>> +
>>  static const struct drm_crtc_helper_funcs tidss_crtc_helper_funcs = {
>>  	.atomic_check = tidss_crtc_atomic_check,
>>  	.atomic_flush = tidss_crtc_atomic_flush,
>>  	.atomic_enable = tidss_crtc_atomic_enable,
>>  	.atomic_disable = tidss_crtc_atomic_disable,
>>  
>> +	.mode_fixup = tidss_crtc_mode_fixup,
>>  	.mode_valid = tidss_crtc_mode_valid,
>>  };
> 
> mode_fixup is deprecated for atomic drivers, so the solution must be
> different there.
> 
> It's also not clear to me how it could change anything there:
> drm_mode_set_crtcinfo with no flags will make crtc_* field exactly
> identical to their !crtc counterparts.
>

I checked the flag options. There isn't any flag required. The only
reason to add this call is because cdns-dsi strictly requires the crtc_*
fields to be populated during the bridge enable.

Secondly, if mode_fixup is deprecated, I think the crtc_atomic_check
would be the next best place to add this call.


Regards
Aradhya