Re: [PATCH v2 02/38] drm/msm/dp: remove dp_display's dp_mode and use dp_panel's instead

[Yongxing Mou <quic_yongmou@quicinc.com>]

On 2025/6/25 22:03, Dmitry Baryshkov wrote:
> On Wed, Jun 25, 2025 at 08:34:18PM +0800, Yongxing Mou wrote:
>>
>>
>> On 2025/6/9 20:48, Dmitry Baryshkov wrote:
>>> On Mon, Jun 09, 2025 at 08:21:21PM +0800, Yongxing Mou wrote:
>>>> From: Abhinav Kumar <quic_abhinavk@quicinc.com>
>>>>
>>>> dp_display caches the current display mode and then passes it onto
>>>> the panel to be used for programming the panel params. Remove this
>>>> two level passing and directly populated the panel's dp_display_mode
>>>> instead.
>>>
>>> - Why do we need to cache / copy it anyway? Can't we just pass the
>>>     corresponding drm_atomic_state / drm_crtc_state / drm_display_mode ?
>>>
>> This part works as follows: .mode_set() copies the adjusted_mode into
>> msm_dp_display_private->msm_dp_display_mode, and also parses and stores
>> variables such as v_active_low/h_active_low/out_fmt_is_yuv_420 and ... When
>> @drm_bridge_funcs.atomic_enable() is called, it copies
>> msm_dp_display->msm_dp_mode into dp_panel->msm_dp_mode and initializes
>> panel_info in msm_dp_display_set_mode(). Then when go to
>> msm_dp_ctrl_on_stream(), the parameters are updated into the corresponding
>> hardware registers.
> 
> So, if we do everything during .atomic_enable(), there would be no need
> to store and/or copy anything. All the data is available and can be used
> as is.
> 
Got it. Let me confirm—can we keep msm_dp_mode or drm_display_mode in 
msm_dp_panel? Mabey debug node will use this ..
>>
>> This design has been in place since the first version of the DP driver and
>> has remained largely unchanged.
> 
> Yes... The point is that you are touching this piece of code anyway,
> let's make it nicer.
> 
Agree with this point.
>> Originally, the drm_mode would be passed in
>> two stages: from msm_dp_display->msm_dp_mode to dp_panel->msm_dp_mode. Since
>> in MST mode each stream requires its own drm_mode and stored in dp_panel, we
>> simplified the two-stage transfer into a single step (.mode_set() do all
>> things and store in msm_dp_panel). Meanwhile we modified the
>> msm_dp_display_set_mode function to accept a msm_dp_panel parameter,
>> allowing the MST bridge funcs' mode_set() to reuse this part code.
>>
>> The following patches:
>> https://patchwork.freedesktop.org/patch/657573/?series=142207&rev=2 and
>> https://patchwork.freedesktop.org/patch/657593/?series=142207&rev=2,
>> introduce msm_dp_display_*_helper functions to help reuse common code across
>> MST/SST/eDP drm_bridge_funcs.
>>
>> If we drop msm_dp_mode from dp_panel and use drm_display_mode, it might
>> introduce a large number of changes that are not directly related to MST.
>> Actually i think the presence of msm_dp_display_mode seems to simplify the
>> work in msm_dp_panel_timing_cfg(), this patch series we want to focus on MST
>> parts, so would we consider optimizing them later?
> 
> Sure... But then you have to change two places. If you optimize it
> first, you have to touch only place. And it can be even submitted
> separately.
> 
Understood, that’s indeed the case. I just want to prioritize the MST 
patch and have it merged first, since it involves changes to lots of 
files. Thanks~~
>>
>> Thanks~
>>>>
>>>> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
>>>> Signed-off-by: Yongxing Mou <quic_yongmou@quicinc.com>
>>>> ---
>>>>    drivers/gpu/drm/msm/dp/dp_display.c | 76 ++++++++++++++-----------------------
>>>>    1 file changed, 29 insertions(+), 47 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c
>>>> index 4a9b65647cdef1ed6c3bb851f93df0db8be977af..9d2db9cbd2552470a36a63f70f517c35436f7280 100644
>>>> --- a/drivers/gpu/drm/msm/dp/dp_display.c
>>>> +++ b/drivers/gpu/drm/msm/dp/dp_display.c
>>>> @@ -92,7 +92,6 @@ struct msm_dp_display_private {
>>>>    	struct msm_dp_panel   *panel;
>>>>    	struct msm_dp_ctrl    *ctrl;
>>>> -	struct msm_dp_display_mode msm_dp_mode;
>>>>    	struct msm_dp msm_dp_display;
>>>>    	/* wait for audio signaling */
>>>> @@ -806,16 +805,29 @@ static int msm_dp_init_sub_modules(struct msm_dp_display_private *dp)
>>>>    }
>>>>    static int msm_dp_display_set_mode(struct msm_dp *msm_dp_display,
>>>> -			       struct msm_dp_display_mode *mode)
>>>> +				   const struct drm_display_mode *adjusted_mode,
>>>> +				   struct msm_dp_panel *msm_dp_panel)
>>>>    {
>>>> -	struct msm_dp_display_private *dp;
>>>> +	u32 bpp;
>>>> -	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>>>> +	drm_mode_copy(&msm_dp_panel->msm_dp_mode.drm_mode, adjusted_mode);
>>>> +
>>>> +	if (msm_dp_display_check_video_test(msm_dp_display))
>>>> +		bpp = msm_dp_display_get_test_bpp(msm_dp_display);
>>>> +	else
>>>> +		bpp = msm_dp_panel->connector->display_info.bpc * 3;
>>>> +
>>>> +	msm_dp_panel->msm_dp_mode.bpp = bpp;
>>>> +
>>>> +	msm_dp_panel->msm_dp_mode.v_active_low =
>>>> +		!!(adjusted_mode->flags & DRM_MODE_FLAG_NVSYNC);
>>>> +	msm_dp_panel->msm_dp_mode.h_active_low =
>>>> +		!!(adjusted_mode->flags & DRM_MODE_FLAG_NHSYNC);
>>>> +	msm_dp_panel->msm_dp_mode.out_fmt_is_yuv_420 =
>>>> +		drm_mode_is_420_only(&msm_dp_panel->connector->display_info, adjusted_mode) &&
>>>> +		msm_dp_panel->vsc_sdp_supported;
>>>> -	drm_mode_copy(&dp->panel->msm_dp_mode.drm_mode, &mode->drm_mode);
>>>> -	dp->panel->msm_dp_mode.bpp = mode->bpp;
>>>> -	dp->panel->msm_dp_mode.out_fmt_is_yuv_420 = mode->out_fmt_is_yuv_420;
>>>> -	msm_dp_panel_init_panel_info(dp->panel);
>>>> +	msm_dp_panel_init_panel_info(msm_dp_panel);
>>>>    	return 0;
>>>>    }
>>>> @@ -1431,10 +1443,13 @@ bool msm_dp_needs_periph_flush(const struct msm_dp *msm_dp_display,
>>>>    bool msm_dp_wide_bus_available(const struct msm_dp *msm_dp_display)
>>>>    {
>>>>    	struct msm_dp_display_private *dp;
>>>> +	struct msm_dp_panel *dp_panel;
>>>>    	dp = container_of(msm_dp_display, struct msm_dp_display_private, msm_dp_display);
>>>> -	if (dp->msm_dp_mode.out_fmt_is_yuv_420)
>>>> +	dp_panel = dp->panel;
>>>> +
>>>> +	if (dp_panel->msm_dp_mode.out_fmt_is_yuv_420)
>>>>    		return false;
>>>>    	return dp->wide_bus_supported;
>>>> @@ -1496,10 +1511,6 @@ void msm_dp_bridge_atomic_enable(struct drm_bridge *drm_bridge,
>>>>    	bool force_link_train = false;
>>>>    	msm_dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display);
>>>> -	if (!msm_dp_display->msm_dp_mode.drm_mode.clock) {
>>>> -		DRM_ERROR("invalid params\n");
>>>> -		return;
>>>> -	}
>>>>    	if (dp->is_edp)
>>>>    		msm_dp_hpd_plug_handle(msm_dp_display, 0);
>>>> @@ -1517,15 +1528,6 @@ void msm_dp_bridge_atomic_enable(struct drm_bridge *drm_bridge,
>>>>    		return;
>>>>    	}
>>>> -	rc = msm_dp_display_set_mode(dp, &msm_dp_display->msm_dp_mode);
>>>> -	if (rc) {
>>>> -		DRM_ERROR("Failed to perform a mode set, rc=%d\n", rc);
>>>> -		mutex_unlock(&msm_dp_display->event_mutex);
>>>> -		return;
>>>> -	}
>>>
>>> It should be done other way around: keep this call and drop
>>> msm_dp_bridge_mode_set().
>>>
>> Emm as reply in last comments..
> 
> Yep. Drop .mode_set, the callback is even described as deprecated.
> 
Thanks, the documentation does state that.
>>>> -
>>>> -	hpd_state =  msm_dp_display->hpd_state;
>>>> -
>>>>    	if (hpd_state == ST_CONNECTED && !dp->power_on) {
>>>>    		msm_dp_display_host_phy_init(msm_dp_display);
>>>>    		force_link_train = true;
>>>> @@ -1604,33 +1606,13 @@ void msm_dp_bridge_mode_set(struct drm_bridge *drm_bridge,
>>>>    	msm_dp_display = container_of(dp, struct msm_dp_display_private, msm_dp_display);
>>>>    	msm_dp_panel = msm_dp_display->panel;
>>>> -	memset(&msm_dp_display->msm_dp_mode, 0x0, sizeof(struct msm_dp_display_mode));
>>>> -
>>>> -	if (msm_dp_display_check_video_test(dp))
>>>> -		msm_dp_display->msm_dp_mode.bpp = msm_dp_display_get_test_bpp(dp);
>>>> -	else /* Default num_components per pixel = 3 */
>>>> -		msm_dp_display->msm_dp_mode.bpp = dp->connector->display_info.bpc * 3;
>>>> -
>>>> -	if (!msm_dp_display->msm_dp_mode.bpp)
>>>> -		msm_dp_display->msm_dp_mode.bpp = 24; /* Default bpp */
>>>> -
>>>> -	drm_mode_copy(&msm_dp_display->msm_dp_mode.drm_mode, adjusted_mode);
>>>> -
>>>> -	msm_dp_display->msm_dp_mode.v_active_low =
>>>> -		!!(msm_dp_display->msm_dp_mode.drm_mode.flags & DRM_MODE_FLAG_NVSYNC);
>>>> -
>>>> -	msm_dp_display->msm_dp_mode.h_active_low =
>>>> -		!!(msm_dp_display->msm_dp_mode.drm_mode.flags & DRM_MODE_FLAG_NHSYNC);
>>>> -
>>>> -	msm_dp_display->msm_dp_mode.out_fmt_is_yuv_420 =
>>>> -		drm_mode_is_420_only(&dp->connector->display_info, adjusted_mode) &&
>>>> -		msm_dp_panel->vsc_sdp_supported;
>>>> +	msm_dp_display_set_mode(dp, adjusted_mode, msm_dp_panel);
>>>>    	/* populate wide_bus_support to different layers */
>>>> -	msm_dp_display->ctrl->wide_bus_en =
>>>> -		msm_dp_display->msm_dp_mode.out_fmt_is_yuv_420 ? false : msm_dp_display->wide_bus_supported;
>>>> -	msm_dp_display->catalog->wide_bus_en =
>>>> -		msm_dp_display->msm_dp_mode.out_fmt_is_yuv_420 ? false : msm_dp_display->wide_bus_supported;
>>>> +	msm_dp_display->ctrl->wide_bus_en = msm_dp_panel->msm_dp_mode.out_fmt_is_yuv_420 ?
>>>> +		false : msm_dp_display->wide_bus_supported;
>>>> +	msm_dp_display->catalog->wide_bus_en = msm_dp_panel->msm_dp_mode.out_fmt_is_yuv_420 ?
>>>> +		false : msm_dp_display->wide_bus_supported;
>>>>    }
>>>>    void msm_dp_bridge_hpd_enable(struct drm_bridge *bridge)
>>>>
>>>> -- 
>>>> 2.34.1
>>>>
>>>
>>
>