From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH] ARM: at91: sama5d3: reduce TWI internal clock frequency Date: Fri, 22 Nov 2013 15:58:35 +0100 Message-ID: <20131122145835.GB7420@katana> References: <1385129228-11225-1-git-send-email-ludovic.desroches@atmel.com> <20131122143350.GA7420@katana> <20131122145141.GB30749@ludovic.desroches@atmel.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="VrqPEDrXMn8OVzN4" Return-path: Content-Disposition: inline In-Reply-To: <20131122145141.GB30749-tOglhBvtKaELqBSMlTbpHvU/3Eu2kcEP@public.gmane.org@atmel.com> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, nicolas.ferre-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org, plagnioj-sclMFOaUSTBWk0Htik3J/w@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --VrqPEDrXMn8OVzN4 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Nov 22, 2013 at 03:51:41PM +0100, Ludovic Desroches wrote: > Hi Wolfram, >=20 > On Fri, Nov 22, 2013 at 03:33:51PM +0100, Wolfram Sang wrote: > > On Fri, Nov 22, 2013 at 03:07:08PM +0100, ludovic.desroches-AIFe0yeh4nAAvxtiuMwx3w@public.gmane.org w= rote: > > > From: Ludovic Desroches > > >=20 > > > There are still I2C unexpected behaviors which are solved by reducing= TWI > > > internal frequency. > > >=20 > > > Cc: #3.10+ > > > Signed-off-by: Ludovic Desroches > >=20 > > I think the commit message needs more details. Is this a true bugfix > > because the real bus frequency was too high because of the wrong > > divider? Is this a workaround which makes things work but will make the > > bus frequency slower than it should be? >=20 > This fix doesn't concern the i2c bus frequency, only the internal IP freq= uency. >=20 > TWI has been validated at 66MHz. With some devices, transfer hangs during= i2c > frame transmission. This issue disappears when reducing the internal freq= uency > of the IP. Maybe there is some oversampling on i2c signals. > Unfortunately, I have no clear status about the root cause that's why > the commit message was imprecise. This paragraph is a way better commit message IMO :) --VrqPEDrXMn8OVzN4 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.15 (GNU/Linux) iQIcBAEBAgAGBQJSj3EbAAoJEBQN5MwUoCm2MFcQAJRqTuplGJlPhc9dAYlGwNMD +8B6LH7ZUOH5SkWBD+uqTWvtu5EiAvGeqvQ2rxXDDf9mAdqWojoLwtXNsYAeF1Ab mUe0z84lP6H7TnIeGm0dIvXXIZ9tJtVSuiiYqTJeCaqRIhG/KpYkyPpCvWRGC4lB MKau8IhfYaL077DHcvcAlhZs6e83GeCST9WAdyTxNK91yPQ47sLuapIhNXR1aExL jbXXk/TR1XhWsq/JBRGWyvA+zD1PknZnLcKeTGWoOUdKZrNkX2kmD8gccuZ0e5JS u1TJhPpxBF5CemYnMAtCQnMYEYuZUxfLvHXAAint84TR3D0UvEpkwOnYdLL5KlLg 1u6LUPpPz8D3hXLMK+mG+tEHyNTIY1koo0ZL/oU+WERk7+afdMP+EZ0gsZTQTb/6 wemLwA0bzM58vE2dsPpFxGWEunghKFnxofdGLIfNrEw1O1fKdK8q8vrjwjKXhHrd 3whnXz5t11/9rAbwFCowUi+e8T7d87y8tKmF6xju6Brbx9U+sz/lwF7QHaYRcXAt gzps9kVoXAkwAKonR5KZ8luUd6AcTbjDbN6zGVNe+ieTThnOrsy/UapybEZTDgYV n3/6uN1B5TV47GcHQ+GbrgrojAlBSLNM+JuJdR03U801SZT4UZRqrxqu6ViDKrNE VD3ffBI0oItjXkMPXecK =Ae7Q -----END PGP SIGNATURE----- --VrqPEDrXMn8OVzN4--