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Date:   Tue, 3 Oct 2023 15:14:55 +0300
From:   Tony Lindgren <tony@atomide.com>
To:     Maximilian Luz <luzmaximilian@gmail.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@intel.com>,
        Dhruva Gole <d-gole@ti.com>,
        Ilpo =?utf-8?B?SsOkcnZpbmVu?= <ilpo.jarvinen@linux.intel.com>,
        John Ogness <john.ogness@linutronix.de>,
        Johan Hovold <johan@kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Vignesh Raghavendra <vigneshr@ti.com>,
        linux-omap@vger.kernel.org,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Subject: Re: [PATCH v12 1/1] serial: core: Start managing serial controllers
 to enable runtime PM
Message-ID: <20231003121455.GB34982@atomide.com>
References: <20230525113034.46880-1-tony@atomide.com>
 <62d3678a-a23d-4619-95de-145026629ba8@gmail.com>
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Hi,

* Maximilian Luz <luzmaximilian@gmail.com> [231003 11:57]:
> A bad workaround is to disable runtime PM, e.g. via
> 
>   echo on > /sys/bus/serial-base/devices/dw-apb-uart.4:0/dw-apb-uart.4:0.0/power/control

If the touchscreen controller driver(s) are using serdev they are
children of the dw-apb-uart.4:0.0 and can use runtime PM calls to
block the parent device from idling as necessary. The hierarchy
unless changed using ignore_children.

Then when the children are done, seem like dw-apb-uart driver should
use force_suspend and force_resume calls in the system suspend path.

Do you have some mainline kernel test case available or is this
still out of tree code?

Regards,

Tony