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([2a02:8071:b783:140:927c:82ba:d32d:99c1]) by smtp.gmail.com with ESMTPSA id w6-20020a5d6806000000b003196b1bb528sm2460004wru.64.2023.10.03.15.09.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 03 Oct 2023 15:09:54 -0700 (PDT) Message-ID: Date: Wed, 4 Oct 2023 00:09:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v12 1/1] serial: core: Start managing serial controllers to enable runtime PM To: Tony Lindgren Cc: Greg Kroah-Hartman , Jiri Slaby , Andy Shevchenko , Dhruva Gole , =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= , John Ogness , Johan Hovold , Sebastian Andrzej Siewior , Vignesh Raghavendra , linux-omap@vger.kernel.org, Andy Shevchenko , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org References: <20230525113034.46880-1-tony@atomide.com> <62d3678a-a23d-4619-95de-145026629ba8@gmail.com> <20231003121455.GB34982@atomide.com> <20231003122137.GC34982@atomide.com> Content-Language: en-US From: Maximilian Luz In-Reply-To: <20231003122137.GC34982@atomide.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On 10/3/23 14:21, Tony Lindgren wrote: > * Tony Lindgren [231003 12:15]: >> Hi, >> >> * Maximilian Luz [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. > > Sorry about all the typos, I meant "the hierarchy works unless changed" > above. The rest of the typos are easier to decipher probably :) Unfortunately that doesn't quite line up with what I can see on v6.5.5. The serdev controller seems to be a child of dw-apb-uart.4, a platform device. The serial-base and serdev devices are siblings. According to sysfs: /sys/bus/platform/devices/dw-apb-uart.4 ├── driver -> ../../../../bus/platform/drivers/dw-apb-uart ├── subsystem -> ../../../../bus/platform │ ├── dw-apb-uart.4:0 │ ├── driver -> ../../../../../bus/serial-base/drivers/ctrl │ ├── subsystem -> ../../../../../bus/serial-base │ │ │ └── dw-apb-uart.4:0.0 │ ├── driver -> ../../../../../../bus/serial-base/drivers/port │ └── subsystem -> ../../../../../../bus/serial-base │ └── serial0 ├── subsystem -> ../../../../../bus/serial │ └── serial0-0 ├── driver -> ../../../../../../bus/serial/drivers/surface_serial_hub └── subsystem -> ../../../../../../bus/serial Runtime suspend on serial0-0 is disabled/not set up at all. So I assume that if it were a descendent of dw-apb-uart.4:0.0, things should have worked out-of-the-box. Regards, Max