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Tue, 24 Sep 2024 16:11:49 +0000 (GMT) Received: from nasanex01b.na.qualcomm.com (nasanex01b.na.qualcomm.com [10.46.141.250]) by NASANPPMTA04.qualcomm.com (8.18.1.2/8.18.1.2) with ESMTPS id 48OGBSJ6008045 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 24 Sep 2024 16:11:28 GMT Received: from [10.134.70.212] (10.80.80.8) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.9; Tue, 24 Sep 2024 09:11:28 -0700 Message-ID: Date: Tue, 24 Sep 2024 09:11:27 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] drm/panel: jd9365da: Modify Kingdisplay and Melfas panel timing To: zhaoxiong lv CC: , , , , , , , , , , , , , References: <20240923134227.11383-1-lvzhaoxiong@huaqin.corp-partner.google.com> <20240923134227.11383-2-lvzhaoxiong@huaqin.corp-partner.google.com> <42f0b4b1-87c7-4ebe-94a1-e2ad1a759dd7@quicinc.com> Content-Language: en-US From: Jessica Zhang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nasanex01b.na.qualcomm.com (10.46.141.250) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-GUID: hEnsDmT1Z1kYu6hjRfrpE6obNy8cT9So X-Proofpoint-ORIG-GUID: hEnsDmT1Z1kYu6hjRfrpE6obNy8cT9So X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-06_09,2024-09-06_01,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 adultscore=0 bulkscore=0 phishscore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 clxscore=1015 mlxscore=0 malwarescore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2409240116 On 9/23/2024 7:13 PM, zhaoxiong lv wrote: > On Tue, Sep 24, 2024 at 5:14 AM Jessica Zhang wrote: >> >> >> >> On 9/23/2024 6:42 AM, Zhaoxiong Lv wrote: >>> In MTK chips, if the system starts suspending before the DRM runtime >>> resume has not completed, there is a possibility of a black screen >>> after waking the machine. Reduce the disable delay resolves this issue, >> >> Hi Zhaoxiong, >> >> Do you mean "if the system starts suspending before the DRM runtime >> resume *has* completed" here? > > Hi Jessica > > Sorry, my description may not be clear enough. It should be when the > DRM runtime resume has not yet completed and the system enters sleep > mode at the same time. Got it, yes I think the reworded explanation in your reply is much clearer. > > >> >>> >>> The "backlight_off_to_display_off_delay_ms" was added between >>> "backlight off" and "display off" to prevent "display off" from being >>> executed when the backlight is not fully powered off, which may cause >>> a white screen. However, we removed this >>> "backlight_off_to_display_off_delay_ms" and found that this situation >>> did not occur. Therefore, in order to solve the problem mentioned >>> above, we We reduced it from 100ms to 3ms (tCMD_OFF >= 1ms). >> >> So from my understanding of this paragraph, >> `backlight_off_to_display_off_delay_ms` was added to prevent the display >> powering off before backlight is fully powered off. You recently tested >> dropping this completely and saw no issue with this. >> >> If that's the case, why not drop this delay completely? >> >> Thanks, >> >> Jessica Zhang > > Yes, there are currently no other issue after removing this delay. > The reason why I didn't completely remove this delay is because the > panel spec states that a delay of more than 1ms (tCMD_OFF >= 1ms) is > required when entering diaplay_off (0x28H), so I reserved 3ms. Thanks for the clarification -- I see why you included the "(tCMD_OFF >= 1ms)" part now. Can you please specify in the commit message that the tCMD_OFF delay requirement is from the spec? Also can you remove the extra "We" in "we We reduced it from 100ms to 3ms"? Thanks, Jessica Zhang > >> >>> >>> This is the timing specification for the two panels: >>> 1. Kingdisplay panel timing spec: >>> https://github.com/KD54183/-JD9365DA_Power-On-Off-Sequence_V0120240923 >>> 2. LMFBX101117480 timing spec: https://github.com/chiohsin-lo/TDY-JD_LIB >>> >>> >>> Fixes: 2b976ad760dc ("drm/panel: jd9365da: Support for kd101ne3-40ti MIPI-DSI panel") >>> Fixes: c4ce398cf18a ("drm/panel: jd9365da: Support for Melfas lmfbx101117480 MIPI-DSI panel") >>> >>> Signed-off-by: Zhaoxiong Lv >>> --- >>> Changes between V2 and V1: >>> - 1. Modify the commit message >>> - 2. Modify the value of backlight_off_to_display_off_delay_ms. >>> v1: https://lore.kernel.org/all/20240915080830.11318-2-lvzhaoxiong@huaqin.corp-partner.google.com/ >>> --- >>> drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c >>> index 44897e5218a6..486aa20e5518 100644 >>> --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c >>> +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c >>> @@ -858,7 +858,7 @@ static const struct jadard_panel_desc kingdisplay_kd101ne3_40ti_desc = { >>> .reset_before_power_off_vcioo = true, >>> .vcioo_to_lp11_delay_ms = 5, >>> .lp11_to_reset_delay_ms = 10, >>> - .backlight_off_to_display_off_delay_ms = 100, >>> + .backlight_off_to_display_off_delay_ms = 3, >>> .display_off_to_enter_sleep_delay_ms = 50, >>> .enter_sleep_to_reset_down_delay_ms = 100, >>> }; >>> @@ -1109,7 +1109,7 @@ static const struct jadard_panel_desc melfas_lmfbx101117480_desc = { >>> .reset_before_power_off_vcioo = true, >>> .vcioo_to_lp11_delay_ms = 5, >>> .lp11_to_reset_delay_ms = 10, >>> - .backlight_off_to_display_off_delay_ms = 100, >>> + .backlight_off_to_display_off_delay_ms = 3, >>> .display_off_to_enter_sleep_delay_ms = 50, >>> .enter_sleep_to_reset_down_delay_ms = 100, >>> }; >>> -- >>> 2.17.1 >>> >>