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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: devicetree@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-Spam-Details-Enc: AW1haW4tMjYwOTExMDA3MSBTYWx0ZWRfX+5DWl9C7K/nn wlcZsIxMroXZXNirMH4yEIcbhX9GyzZ11gDOZZa/8HxX8T8zWaG18J+pYitGfC0YQcFLVhgrBVL V+K70YHryeTKkbH5tocyPb0LTlSGJ09gk9rb0vuzt0heddZzdek1B2dg7OU4WQREeGFnKA/IuR4 vmzOTh88WE/kkujj5DK+Lm+L60tA3ulRbue7cegntGRl3FMasIEgJ1/2a92biEI1LAVu9kuG+9M 4MAq77VrdFzuCxkwTKLl0VCEq1lMJR5O+csegmb8NhQzGs857kTbDCqp15mhZ9x5gOcsID49kBo 7tPpelTufbMdODxHD1hFxa31YfmHbcqHzpkDD3wRZRGQcCH8mjbgKQh53UPwJbpZYpyg69buZ9p OwOPTX2uYv1jqbHevlyq+8cgWAqUd4WH0vAXgXYBwK8cW/KsSAjvArvfqov7R0eOmQ8PKFPK/A1 SOB9kc9Nd5sAT7FyCBA== X-Authority-Analysis: v=2.4 cv=RsxQvymK c=1 sm=1 tr=0 ts=6aa38ebf cx=c_pps a=RP+M6JBNLl+fLTcSJhASfg==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=kj9zAlcOel0A:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=oNE1GLUy8bkFCx8mVIwA:9 a=CjuIK1q_8ugA:10 a=iS9zxrgQBfv6-_F4QbHw:22 X-Proofpoint-GUID: mlWfreDXUjwB3a2EpUp7KlxALhR-gbpM X-Proofpoint-ORIG-GUID: mlWfreDXUjwB3a2EpUp7KlxALhR-gbpM X-Proofpoint-Spam-Info: AW1haW4tMjYwOTExMDA3MSBTYWx0ZWRfX/oZwKrp1M+CM +ajAW0+Pa1pFN4bMFH1u/Xoh9iKuQPgBjgzCWYcwcmEDCnbfMd0d4p1MxSB73TTF12s17HfUdfc AOINvETxYLC8NpJ9IofAhnMnngLvA0k= 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 spamscore=0 lowpriorityscore=0 impostorscore=0 adultscore=0 bulkscore=0 phishscore=0 suspectscore=0 clxscore=1015 priorityscore=1501 malwarescore=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?