linux-kernel - Re: [PATCH v6 1/3] drm/tidss: oldi: Add property to identify OLDI supported VP

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Message-ID: <274d5a5f-0c02-403e-82cf-e966bff7cb62@ideasonboard.com>
Date: Wed, 17 Sep 2025 16:48:42 +0300
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Swamil Jain <s-jain1@...com>
Cc: h-shenoy@...com, devarsht@...com, vigneshr@...com, praneeth@...com,
 u-kumar1@...com, dri-devel@...ts.freedesktop.org,
 linux-kernel@...r.kernel.org, jyri.sarha@....fi,
 maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
 airlied@...il.com, simona@...ll.ch, aradhya.bhatia@...ux.dev
Subject: Re: [PATCH v6 1/3] drm/tidss: oldi: Add property to identify OLDI
 supported VP

Hi,

On 17/09/2025 16:32, Swamil Jain wrote:
> Hi Tomi,
> 
> On 9/16/25 17:10, Tomi Valkeinen wrote:
>> Hi,
>>
>> On 11/09/2025 14:07, Swamil Jain wrote:
>>> From: Jayesh Choudhary <j-choudhary@...com>
>>>
>>> TIDSS should know which VP has OLDI output to avoid calling clock
>>> functions for that VP as those are controlled by oldi driver. Add a
>>> property "is_ext_vp_clk" to "tidss_device" structure for that. Mark it
>>> 'true' in tidss_oldi_init() and 'false' in tidss_oldi_deinit().
>>>
>>> Fixes: 7246e0929945 ("drm/tidss: Add OLDI bridge support")
>>
>> What bug does this fix? It's just adding a new field which it sets to
>> true/false...
> 
> Please take a look: https://lore.kernel.org/all/a0489fea-8c06-4c89-
> a530-8be691f4705d@...com/

There isn't a mention of any issue or fix in the intro letter nor the
patch descriptions, so a fixes tag looks very odd here.

Usually a Fixes tag is for a patch that does the fix. And, of course,
explains what the issue is and what the fix is.

If I understand this right, the fix is this from the patch 2:

+	if (dispc->tidss->is_ext_vp_clk[hw_videoport])
+		return 0;

And patch 3?

Those should be probably made into a single patch that fixes the issue.

Also, bridges have mode_valid callback. Would that be better in patch 3?

 Tomi

> Should we remove the tag?
> Or, else, please suggest a better way to describe the issue mentioned in
> above link.
> 
> Regards,
> Swamil
>>
>>   Tomi
>>
>>> Tested-by: Michael Walle <mwalle@...nel.org>
>>> Reviewed-by: Devarsh Thakkar <devarsht@...com>
>>> Signed-off-by: Jayesh Choudhary <j-choudhary@...com>
>>> Signed-off-by: Swamil Jain <s-jain1@...com>
>>> ---
>>>   drivers/gpu/drm/tidss/tidss_drv.h  | 2 ++
>>>   drivers/gpu/drm/tidss/tidss_oldi.c | 2 ++
>>>   2 files changed, 4 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/tidss/tidss_drv.h b/drivers/gpu/drm/
>>> tidss/tidss_drv.h
>>> index 84454a4855d1..e1c1f41d8b4b 100644
>>> --- a/drivers/gpu/drm/tidss/tidss_drv.h
>>> +++ b/drivers/gpu/drm/tidss/tidss_drv.h
>>> @@ -24,6 +24,8 @@ struct tidss_device {
>>>         const struct dispc_features *feat;
>>>       struct dispc_device *dispc;
>>> +    bool is_ext_vp_clk[TIDSS_MAX_PORTS];
>>> +
>>>         unsigned int num_crtcs;
>>>       struct drm_crtc *crtcs[TIDSS_MAX_PORTS];
>>> diff --git a/drivers/gpu/drm/tidss/tidss_oldi.c b/drivers/gpu/drm/
>>> tidss/tidss_oldi.c
>>> index 7688251beba2..7ecbb2c3d0a2 100644
>>> --- a/drivers/gpu/drm/tidss/tidss_oldi.c
>>> +++ b/drivers/gpu/drm/tidss/tidss_oldi.c
>>> @@ -430,6 +430,7 @@ void tidss_oldi_deinit(struct tidss_device *tidss)
>>>       for (int i = 0; i < tidss->num_oldis; i++) {
>>>           if (tidss->oldis[i]) {
>>>               drm_bridge_remove(&tidss->oldis[i]->bridge);
>>> +            tidss->is_ext_vp_clk[tidss->oldis[i]->parent_vp] = false;
>>>               tidss->oldis[i] = NULL;
>>>           }
>>>       }
>>> @@ -580,6 +581,7 @@ int tidss_oldi_init(struct tidss_device *tidss)
>>>           oldi->bridge.timings = &default_tidss_oldi_timings;
>>>             tidss->oldis[tidss->num_oldis++] = oldi;
>>> +        tidss->is_ext_vp_clk[oldi->parent_vp] = true;
>>>           oldi->tidss = tidss;
>>>             drm_bridge_add(&oldi->bridge);
>>
>