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[103.229.18.19]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34159fc0e19sm391835a91.4.2025.11.03.01.53.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Nov 2025 01:53:32 -0800 (PST) Message-ID: <931eaa75-52f8-4790-9103-02e97b820c7f@oss.qualcomm.com> Date: Mon, 3 Nov 2025 15:23:27 +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 1/2] soc: qcom: smem: Register gunyah watchdog device To: Bjorn Andersson , Guenter Roeck Cc: Konrad Dybcio , Wim Van Sebroeck , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-arm-msm@vger.kernel.org, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Pavan Kondeti , Neil Armstrong , Dmitry Baryshkov References: <20251031-gunyah_watchdog-v4-0-7abb1ee11315@oss.qualcomm.com> <20251031-gunyah_watchdog-v4-1-7abb1ee11315@oss.qualcomm.com> <9421ff80-bd86-4b29-baca-c86da90c91aa@roeck-us.net> Content-Language: en-US From: Hrishabh Rajput In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=P7Q3RyAu c=1 sm=1 tr=0 ts=69087b9e cx=c_pps a=IZJwPbhc+fLeJZngyXXI0A==:117 a=Ou0eQOY4+eZoSc0qltEV5Q==:17 a=IkcTkHD0fZMA:10 a=6UeiqGixMTsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=KKAkSRfTAAAA:8 a=EUspDBNiAAAA:8 a=rzB8HjGg_Mo3OrOr0-EA:9 a=QEXdDO2ut3YA:10 a=uG9DUKGECoFWVXl0Dc02:22 a=cvBusfyB2V15izCimMoJ:22 X-Proofpoint-GUID: 2YwMYdGcji_t4wnP1W9cBU3Ma59m81h5 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUxMTAzMDA5MCBTYWx0ZWRfXwpm3LhtXggvp RnjxX6gLXHqSo/Qxu2e0/0U3yQ6Mchifu6Fbw0QYLBQFbvjSHopaOCYp2S9XyvyGQSmsXVfQ7wE i1R8y8VjhLbbUhxJHGBOVN25wrUY6lE1nu/OIAPHKNVNzqUsRQntdHG8WbZpzaK891qS+UXTbRz 5UO7I/J+qtd3e1qQwQQhOr8gwIqvLNOkj5aR7L5olQuZucHogopBhIVDSBvKlGsAAP3qoFD5u1w GMzHSyDgvJ2dyPblYBA8552Wec0rcMvE/2lW0mb9p0+BPh5bRXHbS+O55dn4Fow1sk6aoYh96K9 k2RXS6gcDwW9FDoHWVtFy8bUHUEUcAmWQ302VWC25hF/EB43yueAMLbdcsrSsv4bDj2glhzSJrc ZmwsmIKcBgDuO8Nk9hE9Z8oEHpN2aw== X-Proofpoint-ORIG-GUID: 2YwMYdGcji_t4wnP1W9cBU3Ma59m81h5 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2025-11-03_01,2025-10-29_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 phishscore=0 clxscore=1015 suspectscore=0 adultscore=0 malwarescore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2510240001 definitions=main-2511030090 On 11/2/2025 12:20 AM, Bjorn Andersson wrote: > On Fri, Oct 31, 2025 at 08:24:44AM -0700, Guenter Roeck wrote: >> On 10/31/25 03:18, Hrishabh Rajput via B4 Relay wrote: >>> From: Hrishabh Rajput >>> >>> To restrict gunyah watchdog initialization to Qualcomm platforms, >>> register the watchdog device in the SMEM driver. >>> >>> When Gunyah is not present or Gunyah emulates MMIO-based >>> watchdog, we expect Qualcomm watchdog or ARM SBSA watchdog device to be >>> present in the devicetree. If none of these device nodes are detected, >>> we register the SMC-based Gunyah watchdog device. >>> >> There should also be an explanation why there is no "qcom,gunyah-wdt" >> devicetree node, both here and in the file. >> >>> Signed-off-by: Hrishabh Rajput >>> --- >>> drivers/soc/qcom/smem.c | 37 +++++++++++++++++++++++++++++++++++++ >>> 1 file changed, 37 insertions(+) >>> >>> diff --git a/drivers/soc/qcom/smem.c b/drivers/soc/qcom/smem.c >>> index cf425930539e..40e4749fab02 100644 >>> --- a/drivers/soc/qcom/smem.c >>> +++ b/drivers/soc/qcom/smem.c >>> @@ -1118,6 +1118,34 @@ static int qcom_smem_resolve_mem(struct qcom_smem *smem, const char *name, >>> return 0; >>> } >>> +static int register_gunyah_wdt_device(void) >>> +{ >>> + struct platform_device *gunyah_wdt_dev; >>> + struct device_node *np; >>> + >>> + /* >>> + * When Gunyah is not present or Gunyah is emulating a memory-mapped >>> + * watchdog, either of Qualcomm watchdog or ARM SBSA watchdog will be >>> + * present. Skip initialization of SMC-based Gunyah watchdog if that is >>> + * the case. >>> + */ >>> + np = of_find_compatible_node(NULL, NULL, "qcom,kpss-wdt"); >>> + if (np) { >>> + of_node_put(np); >>> + return 0; >>> + } >>> + >>> + np = of_find_compatible_node(NULL, NULL, "arm,sbsa-gwdt"); >>> + if (np) { >>> + of_node_put(np); >>> + return 0; >>> + } >>> + >>> + gunyah_wdt_dev = platform_device_register_simple("gunyah-wdt", -1, >>> + NULL, 0); >>> + return PTR_ERR_OR_ZERO(gunyah_wdt_dev); >>> +} >>> + >>> static int qcom_smem_probe(struct platform_device *pdev) >>> { >>> struct smem_header *header; >>> @@ -1236,11 +1264,20 @@ static int qcom_smem_probe(struct platform_device *pdev) >>> if (IS_ERR(smem->socinfo)) >>> dev_dbg(&pdev->dev, "failed to register socinfo device\n"); >>> + ret = register_gunyah_wdt_device(); >>> + if (ret) >>> + dev_dbg(&pdev->dev, "failed to register watchdog device\n"); >>> + >>> return 0; >>> } >>> static void qcom_smem_remove(struct platform_device *pdev) >>> { >>> + /* >>> + * Gunyah watchdog is intended to be a persistent module. Hence, the >>> + * watchdog device is not unregistered. >>> + */ >>> + >> Odd explanation. >> I would assume that the smem device is supposed to be >> persistent as well. > Yes, but it's perfectly possible to run a modern Qualcomm device without > SMEM, with a fair amount of functionality. So, the reevaluation of this > decision is grinding in the back of my mind... One option can be the SCM driver which was suggested by Neil in v3 [1]. Let us know if you have any suggestions where we can register the watchdog device? [1]: https://lore.kernel.org/lkml/321f5289-64c0-48f1-91b5-c45e82396ca9@linaro.org/ Thanks, Hrishabh