linux-kernel - Re: [PATCH v5] watchdog: add driver for StreamLabs USB watchdog device

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Date:   Mon, 1 Aug 2022 11:47:13 +0200
From:   Oliver Neukum <oneukum@...e.com>
To:     Alexey Klimov <klimov.linux@...il.com>,
        Oliver Neukum <oneukum@...e.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        linux-watchdog@...r.kernel.org, wim@...ux-watchdog.org,
        Guenter Roeck <linux@...ck-us.net>,
        USB list <linux-usb@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        atishp@...osinc.com, atishp@...shpatra.org,
        Yury Norov <yury.norov@...il.com>,
        Alexey Klimov <aklimov@...hat.com>,
        Aaron Tomlin <atomlin@...hat.com>
Subject: Re: [PATCH v5] watchdog: add driver for StreamLabs USB watchdog
 device



On 31.07.22 04:34, Alexey Klimov wrote:
> On Tue, Jul 26, 2022 at 8:48 AM Oliver Neukum <oneukum@...e.com> wrote:

> You're right. Upon reset the watchdog is disabled even if it was active before.
> Adding empty ->pre_reset() and ->post_reset() helps to avoid that, but
> looking at Documentation and other drivers it seems that I need to do:
> in pre_reset():
> mutex_lock() to block any other I/O to the usb device;
> __usb_streamlabs_wdt_cmd(STOP) to stop the watchdog;
> and do not unlock the mutex;
> 
> in post_reset():
> if (watchdog_active())
>         __usb_streamlabs_wdt_cmd(START);
> mutex_unlock() to allow other's I/O to the usb deivce.
> 
> Seems right?

Hi,

I suppose if you make reenabling the watchdog conditional,
you may just as well do the same for disabling it.

	Regards
		Oliver