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Tue, 22 Jul 2025 00:18:23 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGfWROZAN8xnaU3AGOGzeHb21uHu6cc8XWYoJJlMXthbXoWRNTVmmRgM4/DanAva3Ppxlpi+A== X-Received: by 2002:a17:90b:1c07:b0:311:e8cc:4264 with SMTP id 98e67ed59e1d1-31c9f3decd2mr33663744a91.12.1753168702519; Tue, 22 Jul 2025 00:18:22 -0700 (PDT) Received: from [10.92.181.248] ([202.46.23.19]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-23e3b6ef976sm69124245ad.202.2025.07.22.00.18.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Jul 2025 00:18:22 -0700 (PDT) Message-ID: Date: Tue, 22 Jul 2025 12:48:18 +0530 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 v4] usb: dwc3: qcom: Remove extcon functionality from glue To: Greg Kroah-Hartman Cc: Thinh Nguyen , Bjorn Andersson , Dmitry Baryshkov , Konrad Dybcio , linux-arm-msm@vger.kernel.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250718053856.2859946-1-krishna.kurapati@oss.qualcomm.com> <2025072021-rounding-oversized-5b4b@gregkh> Content-Language: en-US From: Krishna Kurapati In-Reply-To: <2025072021-rounding-oversized-5b4b@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=EIMG00ZC c=1 sm=1 tr=0 ts=687f3b40 cx=c_pps a=Oh5Dbbf/trHjhBongsHeRQ==:117 a=j4ogTh8yFefVWWEFDRgCtg==:17 a=IkcTkHD0fZMA:10 a=Wb1JkmetP80A:10 a=C-RkopLJPYdHzFFRb_oA:9 a=QEXdDO2ut3YA:10 a=_Vgx9l1VpLgwpw_dHYaR:22 X-Proofpoint-ORIG-GUID: r8fKzIaeda7JMlO4Nz9Q05j_glGo74GS X-Proofpoint-GUID: r8fKzIaeda7JMlO4Nz9Q05j_glGo74GS X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNzIyMDA1OSBTYWx0ZWRfX+fhrq5Wzg+EV xWQDwNGv4fWbSA6F1Y/t6QumHbbKazovaLddQfIN+4d4K3x+15FoPy+y43S5mOZnT/JVq8pH2k2 0v+mJ5y6CA61URFETq0S+k52V3146DKDdh7sgfZoSY5CCbuA6BcSY1HLsgPZh1/mKLx9yVzNsaa fjwdxElNgqX/zLHvB1JXJD+7nnfOblPSeT40WHH9gd4sAG8C9ONpp83f/2SB/XyRMqAEcvuhrMw U2UIVxlDhZ9rZOa/tz1iWq0OtMr99Def6qhSXA+Vnf9ELj8L33SAkNrmELqrfUoMkPMMJIPkx5Q M2VRPRGgR5PZ+J6C0BwYHJIZRgBphmOPyWKkuewGlFB8a/v485xqeXu35uSkTdnIUf30IDmSRUH wTAvxTU8ROgDk93rPuVpdIFL3EiuwWKUhY944TAxsS/BrehrhW4R5hmns4QyejHlX/05YQtM X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-07-22_01,2025-07-21_02,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 mlxscore=0 clxscore=1015 suspectscore=0 malwarescore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2507220059 On 7/20/2025 5:10 PM, Greg Kroah-Hartman wrote: > On Fri, Jul 18, 2025 at 11:08:56AM +0530, Krishna Kurapati wrote: >> Deprecate usage of extcon functionality from the glue driver. > > It's not "deprecate", it is "delete". "deprecate" means that you don't > want future users of this, you are flat out deleting it entirely. > ACK, will rephrase it to "removing code". >> Now >> that the glue driver is a flattened implementation, all existing >> DTs would eventually move to new bindings. > > When is this happening? > >> While doing so let them >> make use of role-switch/ typec frameworks to provide role data >> rather than using extcon. None of the existing in-kernel extcon users >> have moved to using new bindings yet, so this change doesn't affect >> any existing users. > > I don't understand, who does this affect? > >> On upstream, summary of targets/platforms using extcon is as follows: > > What is "upstream" here? In-tree? We only have one development place :) > >> 1. MSM8916 and MSM8939 use Chipidea controller, hence the changes have no >> effect on them. >> >> 2. Of the other extcon users, most of them use "linux,extcon-usb-gpio" >> driver which relies on id/vbus gpios to inform role changes. This can be >> transitioned to role switch based driver (usb-conn-gpio) while flattening >> those platforms to move away from extcon and rely on role switching. > > "most" do, but not all. > >> 3. The one target that uses dwc3 controller and extcon and is not based >> on reading gpios is "arch/arm64/boot/dts/qcom/msm8996-xiaomi-common.dtsi". >> This platform uses TI's Type-C Port controller chip to provide extcon. If >> usb on this platform is being flattened, then effort should be put in to >> define a usb-c-connector device in DT and make use of role switch in >> TUSB320L driver. > > I really still do not understand what is happening here. > > Does this break existing in-tree users? If yes, we can't do that. If > no, they this is just unused code? That's all that we should be > concerned about here. > Thanks for the comments Greg. Basically, all extcon users today use legacy glue bindings (dwc3-qcom-legacy.c). In the new bindings (dwc3-qcom.c), we wanted to remove extcon functionality and enforce usage of usb-role-switch framework instead. So no existing users of extcon would be affected now. But when the above mentioned platforms (the ones that use extcon-usb-gpio driver and msm8996-xiaomi-common.dtsi) are being flattened (by anyone), we want to enforce usage of role-switch (moving to use usb-conn-gpio driver). Would it be clear if I incorporated the following in commit text: 1. Extcon users today use legacy bindings, so this change wont affect any existing in-kernel users since no flattened dT today uses extcon. 2. Extcon code is being removed and usage of role-switch is being encouraged instead. 3. Effort to be be put in while flattening platforms using extcon based on gpio to convert them to use ubs-conn-gpio based on role switch. Let me know your thoughts on this. And thanks for taking the time to review the patch. Regards, Krishna,