From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick Menschel Subject: Re: [PATCH 1/2] dt-binding: can: mcp2517fd: document device tree bindings Date: Fri, 22 Dec 2017 16:50:25 +0100 Message-ID: <94bcc173-1655-f76e-4016-8ff55f59d8b1@posteo.de> References: <20171124183509.12810-1-kernel@martin.sperl.org> <20171124183509.12810-2-kernel@martin.sperl.org> <20171126222528.i6quueqdmuj6le6g@rob-hp-laptop> <6EBDD798-8632-4F42-A138-369BCD36DF68@martin.sperl.org> <0a7e4416-332a-5c23-bda3-8c7561410314@posteo.de> <612BB6CD-5330-40B8-A854-FD065E0A3331@martin.sperl.org> <6aea8071-dc21-4ba7-2b2f-5af41b5755a5@posteo.de> <1ac487f7-17e3-c8a0-0f99-8138fe867373@posteo.de> <4E2DB518-A148-46CE-8267-73D292991BD2@martin.sperl.org> Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms060105010604030507030209" Return-path: In-Reply-To: <4E2DB518-A148-46CE-8267-73D292991BD2-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org Cc: linux-can-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree List-Id: linux-can.vger.kernel.org This is a cryptographically signed message in MIME format. --------------ms060105010604030507030209 Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable Hi Martin, as I wrote earlier, I would save the GPIO_LIB part for a driver update later on as to me there seems to be no daily use case. I think SLEEP is the preferred solution. If the device is in SLEEP after probing, the logical step would be to disable GPIO functions and configure INT0/GPIO0/XSTBY to XSTBY thus the transceiver is also sleeping. Best practice usually comes from practical usage. If there already is a reference design PCB with the mcp2517fd, it would make sense to see what the designer did connect to the optional GPIO pins and then guess what additional use cases could be of interest. Without that knowledge, you're prone to do over-engineering. Regards, Patrick Am 17.12.2017 um 15:34 schrieb kernel-TqfNSX0MhmxHKSADF0wUEw@public.gmane.org: > Hi Patrick! >=20 > So I started implementing the GPIO_LIB implementation but > I have hit an issue where I would like to get some feedback. >=20 > So in principle the gpiolib works, but only if the device is > not asleep and the clock is enabled, which at this very moment means > that the can interface has to be up and running. >=20 > So at this very moment the only option that I see would be to > disable the sleep mode which the device enters after probing until > the can-network interface is enabled (which enables the clock and > start the oscillator) - with SLEEP enabled when GPIOLIB support > is disabled. >=20 > This is obviously not optimal from the power perspective=E2=80=A6 >=20 > The other option would be starting the clock and oscillator > as soon as a set_direction* (or reques/free) function is called. > (where I would need to start using locks to avoid race conditions > as well as clock usage counters...). >=20 > Which of the above is the preferred solution? Are there other ideas > how I could solve this dilemma? >=20 >=20 > Martin >=20 --------------ms060105010604030507030209 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCC CyEwggUzMIIEG6ADAgECAhBp9PwZCVW98tnHAS3kOjLRMA0GCSqGSIb3DQEBCwUAMIGXMQsw CQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxm b3JkMRowGAYDVQQKExFDT01PRE8gQ0EgTGltaXRlZDE9MDsGA1UEAxM0Q09NT0RPIFJTQSBD bGllbnQgQXV0aGVudGljYXRpb24gYW5kIFNlY3VyZSBFbWFpbCBDQTAeFw0xNzA2MDYwMDAw MDBaFw0xODA2MDYyMzU5NTlaMCUxIzAhBgkqhkiG9w0BCQEWFG1lbnNjaGVsLnBAcG9zdGVv LmRlMIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAoNhDbc0RVWdVfJEhvKfjVPmY wnjbpn/YIWexSHoH3L65Gzj0+IHWdI56CvKzWniZYI8pjoCnVQU4gEfRWJqev9wijlagbfYe 0yQQEUFigJEEzC6EoaC5JJfJcNr1qkYB9RSFeSuGnKOb4Z3NGXp0yXjLkY+jzNbRrOelKB6p 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