Re: [PATCH v5 15/17] drm/bridge: analogix_dp: Remove panel disabling and enabling in analogix_dp_set_bridge()

From: Damon Ding <damon.ding@rock-chips.com>
To: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Cc: andrzej.hajda@intel.com, neil.armstrong@linaro.org,
	rfoss@kernel.org, Laurent.pinchart@ideasonboard.com,
	jonas@kwiboo.se, jernej.skrabec@gmail.com,
	maarten.lankhorst@linux.intel.com, mripard@kernel.org,
	tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch,
	jingoohan1@gmail.com, inki.dae@samsung.com,
	sw0312.kim@samsung.com, kyungmin.park@samsung.com,
	krzk@kernel.org, alim.akhtar@samsung.com, hjc@rock-chips.com,
	heiko@sntech.de, andy.yan@rock-chips.com, dianders@chromium.org,
	m.szyprowski@samsung.com, luca.ceresoli@bootlin.com,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-samsung-soc@vger.kernel.org,
	linux-rockchip@lists.infradead.org
Subject: Re: [PATCH v5 15/17] drm/bridge: analogix_dp: Remove panel disabling and enabling in analogix_dp_set_bridge()
Date: Thu, 25 Sep 2025 10:19:26 +0800	[thread overview]
Message-ID: <be24f371-3afa-47ce-a5e8-26f3fac9b6ba@rock-chips.com> (raw)
In-Reply-To: <tywxkfjhulxsgdphngtfs24whslbkmnza7yx2sb7c4ulea6val@46pi6e2sjs6c>

Hi Dmitry,

On 9/12/2025 7:09 PM, Dmitry Baryshkov wrote:
> On Fri, Sep 12, 2025 at 04:58:44PM +0800, Damon Ding wrote:
>> The &drm_panel_funcs.enable() and &drm_panel_funcs.disable() mainly
>> help turn on/off the backlight to make the image visible, and the
>> backlight operations are even needless if drm_panel_of_backlight() or
>> drm_panel_dp_aux_backlight() is applied, in which case the enabling
>> and disabling process just add necessary delays.
> 
> Not necessary, it can actually be turning the panel off and on. Maybe
> it's worth squashing this patch into the panel_bridge conversion as it
> will point out that these functions are still being called at a correct
> times by the DRM bridge framework.
> 

Will do in v6.

>>
>> Therefore, it should make sense to remove panel disabling and move
>> panel enabling after analogix_dp_set_bridge() finished.
>>
>> Signed-off-by: Damon Ding <damon.ding@rock-chips.com>
>> ---
>>   drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 7 +------
>>   1 file changed, 1 insertion(+), 6 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> index 66d0cca1f268..c98058e9c917 100644
>> --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
>> @@ -749,9 +749,6 @@ static int analogix_dp_commit(struct analogix_dp_device *dp)
>>   {
>>   	int ret;
>>   
>> -	/* Keep the panel disabled while we configure video */
>> -	drm_panel_disable(dp->plat_data->panel);
>> -
>>   	ret = analogix_dp_train_link(dp);
>>   	if (ret) {
>>   		dev_err(dp->dev, "unable to do link train, ret=%d\n", ret);
>> @@ -771,9 +768,6 @@ static int analogix_dp_commit(struct analogix_dp_device *dp)
>>   		return ret;
>>   	}
>>   
>> -	/* Safe to enable the panel now */
>> -	drm_panel_enable(dp->plat_data->panel);
>> -
>>   	/* Check whether panel supports fast training */
>>   	ret = analogix_dp_fast_link_train_detection(dp);
>>   	if (ret)
>> @@ -1156,6 +1150,7 @@ static void analogix_dp_bridge_atomic_enable(struct drm_bridge *bridge,
>>   	while (timeout_loop < MAX_PLL_LOCK_LOOP) {
>>   		if (analogix_dp_set_bridge(dp) == 0) {
>>   			dp->dpms_mode = DRM_MODE_DPMS_ON;
>> +			drm_panel_enable(dp->plat_data->panel);
>>   			return;
>>   		}
>>   		dev_err(dp->dev, "failed to set bridge, retry: %d\n",
>> -- 
>> 2.34.1
>>
> 

Best regards,
Damon

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