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Mon, 09 Mar 2026 08:46:25 -0700 (PDT) X-Received: by 2002:a17:902:e54f:b0:2aa:d2f4:9c11 with SMTP id d9443c01a7336-2aea197b7damr709005ad.5.1773071184289; Mon, 09 Mar 2026 08:46:24 -0700 (PDT) Received: from [192.168.29.31] ([49.36.209.2]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2ae83e9d228sm119838665ad.33.2026.03.09.08.46.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Mar 2026 08:46:23 -0700 (PDT) Message-ID: <5488a169-777b-4bb3-9566-78083613d40a@oss.qualcomm.com> Date: Mon, 9 Mar 2026 21:16:19 +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 RFT] driver core: faux: allow to set the firmware node for a faux device To: Bartosz Golaszewski , Greg Kroah-Hartman Cc: Bartosz Golaszewski , "Rafael J. Wysocki" , Danilo Krummrich , linux-arm-msm@vger.kernel.org, driver-core@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260306-faux-dev-with-fwnode-v1-1-792a86a62530@oss.qualcomm.com> <2026030649-evacuate-emotion-422c@gregkh> <2026030612-collapse-empower-285f@gregkh> Content-Language: en-US From: Shivendra Pratap In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Proofpoint-GUID: bMTqw6UgTaZ5KQCKDzlItWCuz07c7pst X-Proofpoint-ORIG-GUID: bMTqw6UgTaZ5KQCKDzlItWCuz07c7pst X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzA5MDE0MiBTYWx0ZWRfXzBXoNFyIhXos jXYE8RK+/TZTcScZJfWmOU48sPiLIZhDslTCXUPODiZVYH1uzKDRP5aQVDqcqMF8XJGYUlw9aqb 0wHZ1gJn2OJy+Ah1TBJ3teHMK2SJo3XPn/3oe5TbLScW2XdGDekYxQujCnYlbB8rP6NlYVNND6A hwFEEL0QsnJO0XWqzCDwRUii+4adPWO2WLONKVCmE7iS6j5fouPzjDSOS967X8MYk6RHx+Uol+8 h4hVxh1UWjlelfLS0K17834TaJTnofvXJmh+8ZphInnaoukCX777fE1WuNgi/GFhh/GbUyJsBRa onL0ZaxT46BujEbDu+tLhx/+aifSlJkxckHl6DIvxujpms95Z/DkYu4MGYACU3zzpxwr14c2Ish eX5R7n7IfUIMmrQB2ANRuN0JvOBpuNu+UUDqXdmFGMN92JZhOUvLn4xabztxDh/aN5y9q7hYZwi yz0idpUJu43nn3lFnfA== X-Authority-Analysis: v=2.4 cv=Xr/3+FF9 c=1 sm=1 tr=0 ts=69aeeb52 cx=c_pps a=cmESyDAEBpBGqyK7t0alAg==:117 a=SibS68aVnxHiogvcwlKZDA==:17 a=IkcTkHD0fZMA:10 a=Yq5XynenixoA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=VwQbUJbxAAAA:8 a=ag1SF4gXAAAA:8 a=EUspDBNiAAAA:8 a=__pY0jlSMTdJdk2JTmwA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=1OuFwYUASf3TG4hYMiVC:22 a=Yupwre4RP9_Eg_Bd0iYG:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-03-09_04,2026-03-09_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 adultscore=0 spamscore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 clxscore=1015 phishscore=0 priorityscore=1501 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2602130000 definitions=main-2603090142 On 06-03-2026 19:54, Bartosz Golaszewski wrote: > On Fri, Mar 6, 2026 at 3:13 PM Greg Kroah-Hartman > wrote: >> >> On Fri, Mar 06, 2026 at 03:07:03PM +0100, Bartosz Golaszewski wrote: >>> On Fri, Mar 6, 2026 at 2:54 PM Greg Kroah-Hartman >>> wrote: >>>> >>>> On Fri, Mar 06, 2026 at 02:45:56PM +0100, Bartosz Golaszewski wrote: >>>>> Add a new variant of faux_device_create() taking a firmware node handle >>>>> as argument and attaching it to the created faux device. This allows >>>>> users to define and read device properties using the standard property >>>>> accessors. >>>> >>>> Why would a faux device have firmware backing? Doesn't that mean it >>>> should be a platform device? >>>> >>>>> While at it: order includes in faux.c alphabetically for easier >>>>> maintenance. >>>> >>>> Hint, that should be a separate patch, and is never something that I >>>> enforce or require in .c files I maintain :) >>>> >>>>> Signed-off-by: Bartosz Golaszewski >>>>> --- >>>>> Hi Shivendra et al! >>>>> >>>>> This patch is related to my response to your reboot-mode patch[1]. >>>>> >>>>> You should be able to use the new function like: >>>>> >>>>> faux_device_create_full("psci-reboot-mode", NULL, NULL, NULL, of_fwnode_handle(np)); >>>> >>>> What is the fwnode handle here for? Why is it required at all? What >>>> resources are involved that would want this? >>>> >>> >>> Shivendra creates a faux device that registers with the reboot-mode >>> subsystem which reads the reboot-mode definitions from devicetree. The >>> faux device needs to have the "reboot-mode" OF-node attached. In his >>> current proposal, Shivenda had to bypass faux device's probe() because >>> he can't have the fwnode attached before probe() is called. >> >> Why would a firmware device be attached to a faux device? A firmware >> device is, implicitly, already part of the firmware "device tree", so >> there should be something for it to be a child of already in the system. >> > > Shivendra: I rememeber there was an issue with using any proper > devices like platform or auxiliary with this but - as the series is > already at v20 - I can't find the actual discussion. Could you please > describe what the issue with driver matching was? reboot-mode node is a property of psci which defines the reboot commands.‌ As its not an actual device we wanted to avoid creating platform or aux device. few references here: https://lore.kernel.org/all/rz7tnl5gg73gtyij3kmwk6hubikfsvu3krekjkpoofpdio6cwe@innio7qvotye/ Till v17, we were exposing an explicit of_node based registration in reboot mode and then registering it from psci driver. Post this, Lorenzo suggested to move this outside of psci and use a faux device instead. thanks, Shivendra