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Mon, 24 Aug 2026 10:43:41 -0700 (PDT) X-Received: by 2002:a05:6a21:4d8b:b0:3cd:6f46:aceb with SMTP id adf61e73a8af0-3cd91103da8mr982668637.8.1787593421228; Mon, 24 Aug 2026 10:43:41 -0700 (PDT) Received: from localhost ([50.35.46.84]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-327f91d2d1esm29442144eec.17.2026.08.24.10.43.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 24 Aug 2026 10:43:40 -0700 (PDT) Date: Mon, 24 Aug 2026 10:43:37 -0700 From: Jonathan Cameron To: Sudeep Holla Cc: arm-scmi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@meta.com, Cristian Marussi , Breno Leitao Subject: Re: [PATCH v3 4/9] firmware: arm_scmi: Fall back to ACPI HID when "compatible" is absent Message-ID: <20260824104337.00002275@oss.qualcomm.com> In-Reply-To: <20260813-acpi_scmi_pcc-v3-4-cb6b88b4ebb3@kernel.org> References: <20260813-acpi_scmi_pcc-v3-0-cb6b88b4ebb3@kernel.org> <20260813-acpi_scmi_pcc-v3-4-cb6b88b4ebb3@kernel.org> Organization: Qualcomm X-Mailer: Claws Mail 4.4.0 (GTK 3.24.51; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: arm-scmi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: cke6oarJ3eewrdpUsjBaadlFCXJ6IQXR X-Proofpoint-GUID: cke6oarJ3eewrdpUsjBaadlFCXJ6IQXR X-Proofpoint-Spam-Info: AW1haW4tMjYwODI0MDE0OSBTYWx0ZWRfXzhPRnkK83SX9 Izl7ww6YjsP3WIRmffKR2MN2aqngJU28/UZQsYi/8gpqmNiq7d9g5MfnFf3VrgwHUUVYkC5fHQ7 Vokv8yevK2hdXzbNk6YlOKsUTcPQXHQ= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI0MDE0OSBTYWx0ZWRfX1UbQG1Rw+Oiy FBjwb4GGBRrCN5b3QHEoPWInT/FDlM+CrIA6EB3+/KVSpZ8OQF33lJpikMvVS288v/OSn/4Ce/R VP4P2NIPDbbcy9ejBllX+dzHy6bP7P6SBNpPagRMQnQERFwvjkHoP/sTkzzGXv8jdZRv3Wospcy iJhWFtCxyd8lQiFnaS+sU7L9cfAoK7jwtxwsmkP4uC4dMpj2sOxZfsG7k/S2KiS+IjpptpIEAPP H8WyyKXdwqnI83/ltyxe3s3M705iIvJGpXLhwbHcVpc9bX9aaz4Q/kqTXetXmlEWqq3CWRUSbSo DOujFmZN8hgTnTtcd3vRQFtFBVttHO6vbZnv32VLp7xP1+WDXUNep2SpgdHI5iv/zE8ahB6yuQZ 8xNuAgPeEVMmDJyMHPfwZ68Y7ZaYEFsI81cB+UgxyoRSUfXIyYGEr6jJ5/mbfiew8O4Bioma5aH SVipdXPAkuA8+Fd2YTQ== X-Authority-Analysis: v=2.4 cv=KcvidwYD c=1 sm=1 tr=0 ts=6a8c82d0 cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=qC1CW/w66vtJz1P9yTJxNA==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=VwQbUJbxAAAA:8 a=l6Goj-m7ziazzFgbZv4A:9 a=CjuIK1q_8ugA:10 a=zc0IvFSfCIW2DFIPzwfm:22 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=2026-08-24_05,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 impostorscore=0 adultscore=0 spamscore=0 priorityscore=1501 lowpriorityscore=0 bulkscore=0 clxscore=1015 suspectscore=0 malwarescore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608240149 On Thu, 13 Aug 2026 12:32:59 +0100 Sudeep Holla wrote: > scmi_debugfs_common_setup() uses the "compatible" property to > populate the debugfs transport type string. ACPI-described SCMI > devices do not provide that DT property, so the string remains > NULL and debugfs setup falls through the allocation failure path. > > Check the property lookup result and use the ACPI HID as the > fallback transport type when an ACPI companion is present. > > All supported DT SCMI platforms are expected to provide "compatible", > so the non-ACPI fallback is not needed for normal DT operation. Keep > the explicit "unknown" fallback anyway to avoid passing NULL to > kstrdup() if that assumption is ever violated. > > Signed-off-by: Sudeep Holla Can drop some complexity in here and rely on the stubs in acpi.h a little more. > --- > drivers/firmware/arm_scmi/driver.c | 16 ++++++++++++++-- > 1 file changed, 14 insertions(+), 2 deletions(-) > > diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c > index 9014723e0f7f..9ad827c6a9ab 100644 > --- a/drivers/firmware/arm_scmi/driver.c > +++ b/drivers/firmware/arm_scmi/driver.c > @@ -16,6 +16,7 @@ > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > +#include > #include > #include > #include > @@ -3063,6 +3064,15 @@ static void scmi_debugfs_common_cleanup(void *d) > kfree(dbg->type); > } > > +static const char *scmi_acpi_device_hid(struct acpi_device *adev) > +{ > +#ifdef CONFIG_ACPI Hmm. Ugly that acpi_device_id returns an empty string. However given when !CONFIG_ACPI the stub for ACPI_COMPANION(dev) is NULL. You don't need this dance anyway. > + return adev ? acpi_device_hid(adev) : "unknown"; > +#else > + return "unknown"; > +#endif > +} > + > static struct scmi_debug_info *scmi_debugfs_common_setup(struct scmi_info *info) > { > char top_dir[16]; > @@ -3080,8 +3090,10 @@ static struct scmi_debug_info *scmi_debugfs_common_setup(struct scmi_info *info) > return NULL; > } > > - fwnode_property_read_string(dev_fwnode(info->dev), "compatible", > - &c_ptr); > + if (fwnode_property_read_string(dev_fwnode(info->dev), "compatible", > + &c_ptr)) > + c_ptr = scmi_acpi_device_hid(ACPI_COMPANION(info->dev)); > + > dbg->type = kstrdup(c_ptr, GFP_KERNEL); > if (!dbg->type) { > kfree(dbg->name); >