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[103.229.18.19]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-34db4c1ef93sm3065432eec.28.2026.09.30.19.45.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 19:45:17 -0700 (PDT) Date: Thu, 1 Oct 2026 08:15:07 +0530 From: Vishnu Saini To: Philipp Zabel Cc: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Marek Vasut , dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Yi Zhang , Nilesh Laad , Gopi Botlagunta , venkata.valluru@oss.qualcomm.com, Jessica Zhang Subject: Re: [PATCH v9 2/2] drm/bridge: add support for lontium lt9211c bridge Message-ID: References: <20260924-add-lt9211c-bridge-v9-0-d78b39677a61@oss.qualcomm.com> <20260924-add-lt9211c-bridge-v9-2-d78b39677a61@oss.qualcomm.com> <61aa851b26f9aa85a3ec1dc4bc8f46d7f1fbd24e.camel@pengutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <61aa851b26f9aa85a3ec1dc4bc8f46d7f1fbd24e.camel@pengutronix.de> X-Authority-Analysis: v=2.4 cv=Gr3XaU1C c=1 sm=1 tr=0 ts=6abdc93f cx=c_pps a=PfFC4Oe2JQzmKTvty2cRDw==:117 a=Ou0eQOY4+eZoSc0qltEV5Q==:17 a=kj9zAlcOel0A:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=3WHJM1ZQz_JShphwDgj5:22 a=EUspDBNiAAAA:8 a=10iAqneoWiIgQKNWSb8A:9 a=CjuIK1q_8ugA:10 a=6Ab_bkdmUrQuMsNx7PHu:22 X-Proofpoint-Spam-Info: AW1haW4tMjYxMDAxMDAxMCBTYWx0ZWRfX0n1bXt6HU6RG 51U6Y9rn74Ejc1jBpy7Oxax72BqwJoXYAvkYEBWrNCO+S+7hJW3Jjh61TX1dSbjPlzXglU8KdzX HSHFPsREnZlrbvknruuHDW32b+zoke0= X-Proofpoint-GUID: bMwBOrEHRckyzdTd99E7G2M91hzF2rQV X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDAxMDAxMCBTYWx0ZWRfXzyl/WQv941FX Q2xncXQ4l0xodv1lVG+Z3+DFUwDBhG0Tevbfn+M3OdL5EWJqHkzSmQ/Rv4jOW82yuDBprTcVcGK yNE6pRkT2D5O3xlf2Cj8E2tjvHW73wbPJU+7/oM9jW/daH7XcZqr8KmKW8Q8tGYnHVJdaoSXFDf 74ADe7VWqBF5l+VEjh/5lMwb4Ul2Jmy92UrQQZhmaZZmdre9DFhyMQ5KG2bARIrYRWdeHXQoy/G KjTX06jaH5wbva4vknynj5B3PGEq65xylu4KppvfiglvHvXj2odz11dKpfKYDobW1w+XBRUyGUi 4pPjGNpdyr93wMZ7AA+dXZkl/blcc/Gz9KlqIIp3m8+joW2zu+S1YXIdejYr0Sc3YXkubX+GqI8 kTypdMmHN94PGnzhn/x/gRtO7anveQlGApmP1mIcn3VoWbM+KZdXM6XiHlDfumKmrx2uimBcXuR VzzXIbioF1xNQs3v9dw== X-Proofpoint-ORIG-GUID: bMwBOrEHRckyzdTd99E7G2M91hzF2rQV X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-01_01,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 malwarescore=0 adultscore=0 lowpriorityscore=0 spamscore=0 suspectscore=0 impostorscore=0 priorityscore=1501 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2610010010 On Fri, Sep 25, 2026 at 03:23:28PM +0200, Philipp Zabel wrote: > On Do, 2026-09-24 at 21:29 +0530, vishnu.saini@oss.qualcomm.com wrote: > > From: Yi Zhang > > > > LT9211C is a Single/Dual-Link DSI/LVDS or Single DPI input to > > Single-Link/Dual-Link DSI/LVDS or Single DPI output bridge chip. > > Extend the existing lontium-lt9211 driver to support DSI-to-LVDS > > bridge configuration by detecting and handling both LT9211 and LT9211C > > variants from a single driver. > > > > Chip detection in lt9211_read_chipid() is extended to identify the > > LT9211C by its distinct chip ID registers, and cross-checked against > > the chip type requested by the DT compatible string to catch a > > mismatched board/compatible combination. > > > > Add LT9211C-specific regmap support and use lt9211_chip_data with > > i2c_get_match_data() to provide per-chip configuration. > > > > Five new functions implement the LT9211C DSI-to-LVDS initialisation > > sequence: lt9211c_configure_rx(), lt9211c_autodetect_rx(), > > lt9211c_configure_timing(), lt9211c_configure_plls() and > > lt9211c_configure_tx(). > > > > Defer the remaining LT9211C initialization to a work item scheduled > > from atomic_enable(), since RX auto-detection requires an active DSI > > stream. > > This is still wrong, and I don't understand why you need it. > > All scheduling initialization as a work item should allow is for > downstream bridges and/or panels to be atomic_enabled while > lt9211_work_func() is waiting for a vblank interrupt. > They expect the LVDS signal to be active at this point. If LVDS is > enabled at some unknown later point in time by the work item, any > startup timing requirements the panel might have can not be applied > correctly. Sorry for late, delayed work is now called at first vblank irq itself. I think it will not miss the initial few frames. But i will check more on DSI host side. > Also, deferring initialization as a work item shouldn't have any > influence on the upstream DSI signal. That should already be active > when lt9211c atomic_enable is called. Could it be that there is a bug > in your display controller or DSI bridge driver that causes the DSI > signal to still not be completely active at this point? yes there is some issue in msm/dsi host driver as DSI signal is not active at atomic_enable > > Signed-off-by: Yi Zhang > > Signed-off-by: Nilesh Laad > > Signed-off-by: Gopi Botlagunta > > Signed-off-by: Vishnu Saini > > Tested-by: Philipp Zabel > > I have not tested this version (yet). Ok, i will remove in next revision. > > regards > Philipp