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Tue, 31 Mar 2020 09:08:30 -0700 (PDT) Subject: Re: [PATCH 2/3] watchdog: da9063: Use pre configured timeout when watchdog is running To: Adam Thomson , Stefan Riedmueller , Wim Van Sebroeck , Support Opensource Cc: "linux-watchdog@vger.kernel.org" , "linux-kernel@vger.kernel.org" References: <20200326150203.371673-1-s.riedmueller@phytec.de> <20200326150203.371673-2-s.riedmueller@phytec.de> 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: <387fadc6-1eab-ada7-86dd-0e47c5e9cb9f@roeck-us.net> Date: Tue, 31 Mar 2020 09:08:29 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-watchdog-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org On 3/30/20 9:38 AM, Adam Thomson wrote: > On 26 March 2020 15:02, Stefan Riedmueller wrote: > >> If the watchdog is already running during probe use its pre-configured >> timeout instead of a default timeout to make sure the watchdog is pinged >> in time until userspace takes over. > > At least for this driver I don't think there's an issue here with regards to > not pinging in time. Calling 'da9063_wdt_update_timeout()', as it currently > does in the probe() when the watchdog is already active, actually disables the > watchdog before then setting a new timeout value, so by that method we're > avoiding a timeout and starting a new timer period. > > To my mind the timeout value should come from DT if possible, which I would > assume for the most part would match whatever is defined in the bootloader as > well, unless I'm mistaken. If that's not available though then I would maybe > agree on falling back to a value that was already programmed in the bootloader > rather than the driver default which should be the last resort. > Agreed. Guenter >> >> Signed-off-by: Stefan Riedmueller >> --- >> drivers/watchdog/da9063_wdt.c | 29 ++++++++++++++++++----------- >> 1 file changed, 18 insertions(+), 11 deletions(-) >> >> diff --git a/drivers/watchdog/da9063_wdt.c b/drivers/watchdog/da9063_wdt.c >> index 3d65e92a4e3f..34d0c4f03814 100644 >> --- a/drivers/watchdog/da9063_wdt.c >> +++ b/drivers/watchdog/da9063_wdt.c >> @@ -46,15 +46,16 @@ static unsigned int da9063_wdt_timeout_to_sel(unsigned >> int secs) >> } >> >> /* >> - * Return 0 if watchdog is disabled, else non zero. >> + * Read the currently active timeout. >> + * Zero means the watchdog is disabled. >> */ >> -static unsigned int da9063_wdt_is_running(struct da9063 *da9063) >> +static unsigned int da9063_wdt_read_timeout(struct da9063 *da9063) >> { >> unsigned int val; >> >> regmap_read(da9063->regmap, DA9063_REG_CONTROL_D, &val); >> >> - return val & DA9063_TWDSCALE_MASK; >> + return wdt_timeout[val & DA9063_TWDSCALE_MASK]; >> } >> >> static int da9063_wdt_disable_timer(struct da9063 *da9063) >> @@ -191,6 +192,7 @@ static int da9063_wdt_probe(struct platform_device >> *pdev) >> struct device *dev = &pdev->dev; >> struct da9063 *da9063; >> struct watchdog_device *wdd; >> + int timeout; >> >> if (!dev->parent) >> return -EINVAL; >> @@ -214,15 +216,20 @@ static int da9063_wdt_probe(struct platform_device >> *pdev) >> watchdog_set_restart_priority(wdd, 128); >> watchdog_set_drvdata(wdd, da9063); >> >> - /* Set default timeout, maybe override it with DT value, scale it */ >> - wdd->timeout = DA9063_WDG_TIMEOUT; >> - watchdog_init_timeout(wdd, 0, dev); >> - da9063_wdt_set_timeout(wdd, wdd->timeout); >> - >> - /* Change the timeout to the default value if the watchdog is running */ >> - if (da9063_wdt_is_running(da9063)) { >> - da9063_wdt_update_timeout(da9063, wdd->timeout); >> + /* >> + * Use pre-configured timeout if watchdog is already running. >> + * Otherwise set default timeout, maybe override it with DT value, >> + * scale it >> + */ >> + timeout = da9063_wdt_read_timeout(da9063); >> + if (timeout) { >> + wdd->timeout = timeout; >> set_bit(WDOG_HW_RUNNING, &wdd->status); >> + dev_info(da9063->dev, "watchdog is running (%u s)", timeout); >> + } else { >> + wdd->timeout = DA9063_WDG_TIMEOUT; >> + watchdog_init_timeout(wdd, 0, dev); >> + da9063_wdt_set_timeout(wdd, wdd->timeout); >> } >> >> return devm_watchdog_register_device(dev, wdd); >> -- >> 2.23.0 >