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Thu, 10 Sep 2026 22:16:45 -0700 (PDT) Received: from hu-ssmaurya-hyd.qualcomm.com ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33ba4ed64fcsm3419325eec.16.2026.09.10.22.16.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 22:16:44 -0700 (PDT) Date: Fri, 11 Sep 2026 10:46:37 +0530 From: Shashank Maurya To: Conor Dooley Cc: Mark Brown , Liam Girdwood , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Broadcom internal kernel review list , Marek Vasut , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, venkata.valluru@oss.qualcomm.com, Jessica Zhang Subject: Re: [PATCH v2 2/2] regulator: rpi-panel-v2: Add required vcc-supply support Message-ID: References: <20260907-rpi_reg-v2-0-0c59aa60d31f@oss.qualcomm.com> <20260907-rpi_reg-v2-2-0c59aa60d31f@oss.qualcomm.com> <20260907-ensnare-wanted-e86eeaf770b0@spud> <27fb1c11-c1eb-4494-ac38-d794baf80814@sirena.org.uk> <20260907-showroom-elevation-ba1a0792b7f7@spud> 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: <20260907-showroom-elevation-ba1a0792b7f7@spud> X-Proofpoint-ORIG-GUID: 4o42IOPh-VZ-ZR3f901DCAe8CieEhf8Z X-Proofpoint-GUID: 4o42IOPh-VZ-ZR3f901DCAe8CieEhf8Z X-Authority-Analysis: v=2.4 cv=PchqFShd c=1 sm=1 tr=0 ts=6aa38ebf cx=c_pps a=vVfyC5vLCtgYJKYeQD43oA==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=oNE1GLUy8bkFCx8mVIwA:9 a=CjuIK1q_8ugA:10 a=rl5im9kqc5Lf4LNbBjHf:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTExMDA3MSBTYWx0ZWRfX3zuknWMkOc4g hjPiGWfZNaiebORq9R6CIOpShtyujEFf0jHRQxVptlvhmb+MWx1Nq5F7vWKt5Nlh+9GaPxQfbJk 1rnZWdJXjf05b9KOS1FE4RSj4WZ+V3Lk0F/lBLwnU4IbTbI503jqk/qKEC4XYD29szbdxVwv2W0 LyMYD3BQrk/fKc7oKRwftRM1cPb7wsilAvXu9e6Cf23+r0dfmIyyohrQQ9LgwV316WV60wYJM1B WzWPTZv0wJAOfm8qFPhFc0B2nMWptMpw5dVUK6oZKp+M3pkP+JeJ339dVNxPtgbPfr/iNE4wMFg get7nfp4lqC90Sm5jfXl5GxuLB7pAFx+gIX5Zhvqb1fH1qymWy8Pret+VVT7DPLzNbeEdsN5vyI g2e846YNwMpLqhrTdw1srT9ojUmpNYIIaCQ2HRF4pBlPXx+KywKZiF3LjANMEfgaMmBITqY+dZd 9Fpw+sl1i83hb6ybI4g== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTExMDA3MSBTYWx0ZWRfX4Vbekx+pJe1k 96h3fYru2a+ju7Pz+nyhZKILCpTSzCA7uHQMEgtLNezLy2qWHEWtS0NAU9+Y+SK9XoQy+UH5PLY +ef32/eRZmWqnRpR9oawuaBo20cGDBM= 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=2026-09-11_02,2026-09-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 malwarescore=0 spamscore=0 adultscore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 bulkscore=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-2609110071 On Mon, Sep 07, 2026 at 07:04:21PM +0100, Conor Dooley wrote: > On Mon, Sep 07, 2026 at 06:09:57PM +0100, Mark Brown wrote: > > On Mon, Sep 07, 2026 at 06:06:24PM +0100, Conor Dooley wrote: > > > On Mon, Sep 07, 2026 at 11:16:08AM +0530, Shashank Maurya wrote: > > > > > > + vcc = devm_regulator_get(&i2c->dev, "vcc"); > > > > + if (IS_ERR(vcc)) > > > > + return dev_err_probe(&i2c->dev, PTR_ERR(vcc), > > > > + "Failed to get vcc supply\n"); > > > > > This needs to be optional, because without it you'll break existing > > > devicetrees. Unless you can explain how all existing users are > > > nonfunctional (e.g. nothing ever enabled the supply, which seems > > > doubtful given this surely worked when it was added) this must remain > > > optional. > > > > The core will stub in a dummy regulator for mandatory supplies that > > don't have anything mapped by firmware, otherwise essentially all > > regualtors would be optional and our error handling would be a disaster > > zone. > > I always forget how this works. Thanks for the reminder. > > Thanks Mark and Conor for the clarification. To summarize: the binding marks vcc-supply as required (since the hardware genuinely needs this rail), and the driver uses devm_regulator_get() which lets the regulator core provide a dummy stub for existing devicetrees that don't specify the supply. This keeps backward compatibility intact. Is the series good to go as-is, or is there anything else you'd like me to address in a v3?