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Sun, 05 Jul 2020 07:58:03 -0700 (PDT) Subject: Re: [PATCHv2 2/5] watchdog: add support for adjusting last known HW keepalive time To: Tero Kristo , wim@linux-watchdog.org, linux-watchdog@vger.kernel.org Cc: linux-kernel@vger.kernel.org, jan.kiszka@siemens.com References: <20200703120406.7092-1-t-kristo@ti.com> <20200703120406.7092-3-t-kristo@ti.com> From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= Message-ID: Date: Sun, 5 Jul 2020 07:58:02 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200703120406.7092-3-t-kristo@ti.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 7/3/20 5:04 AM, Tero Kristo wrote: > Certain watchdogs require the watchdog only to be pinged within a > specific time window, pinging too early or too late cause the watchdog > to fire. In cases where this sort of watchdog has been started before > kernel comes up, we must adjust the watchdog keepalive window to match > the actually running timer, so add a new driver API for this purpose. > > Signed-off-by: Tero Kristo > --- > drivers/watchdog/watchdog_dev.c | 23 +++++++++++++++++++++++ > include/linux/watchdog.h | 2 ++ > 2 files changed, 25 insertions(+) > > diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c > index bc1cfa288553..5848551cf29d 100644 > --- a/drivers/watchdog/watchdog_dev.c > +++ b/drivers/watchdog/watchdog_dev.c > @@ -1138,6 +1138,29 @@ void watchdog_dev_unregister(struct watchdog_device *wdd) > watchdog_cdev_unregister(wdd); > } > > +/* > + * watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog > + * > + * Adjusts the last known HW keepalive time for a watchdog timer. > + * This is needed in case where watchdog has been started before > + * kernel by someone like bootloader, and it can't be pinged ... needed if the watchdog is already running when the probe function is called, and ... > + * immediately. This adjusts the watchdog ping period to match > + * the currently running timer. It doesn't adjust the ping period. > + */ last_ping_ms needs to be documented (the last heartbeat was last_ping_ms milliseconds ago ?), both here and in Documentation/watchdog/watchdog-kernel-api.rst. It needs to be documented that the function must be called immediately after watchdog registration, and that min_hw_heartbeat_ms must be set for it to be useful. > +int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd, > + unsigned int last_ping_ms) > +{ > + struct watchdog_core_data *wd_data = wdd->wd_data; This needs a NULL check, in case it is called before watchdog driver registration. > + ktime_t now; > + > + now = ktime_get(); > + > + wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms)); > + > + return __watchdog_ping(wdd); > +} > +EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive); > + > /* > * watchdog_dev_init: init dev part of watchdog core > * > diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h > index 1464ce6ffa31..9b19e6bb68b5 100644 > --- a/include/linux/watchdog.h > +++ b/include/linux/watchdog.h > @@ -210,6 +210,8 @@ extern int watchdog_init_timeout(struct watchdog_device *wdd, > extern int watchdog_register_device(struct watchdog_device *); > extern void watchdog_unregister_device(struct watchdog_device *); > > +int watchdog_set_last_hw_keepalive(struct watchdog_device *, unsigned int); > + > /* devres register variant */ > int devm_watchdog_register_device(struct device *dev, struct watchdog_device *); > >