From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfram Sang Subject: Re: [PATCH v2 1/2] i2c-designware: make HCNT/LCNT values configurable Date: Wed, 28 Aug 2013 11:10:19 +0200 Message-ID: <20130828091019.GD4086@katana> References: <1376914074-31103-1-git-send-email-mika.westerberg@linux.intel.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="/3yNEOqWowh/8j+e" Return-path: Content-Disposition: inline In-Reply-To: <1376914074-31103-1-git-send-email-mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mika Westerberg Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christian Ruppert , Shinya Kuribayashi , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org --/3yNEOqWowh/8j+e Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Aug 19, 2013 at 03:07:53PM +0300, Mika Westerberg wrote: > The DesignWare I2C controller has high count (HCNT) and low count (LCNT) > registers for each of the I2C speed modes (standard and fast). These > registers are programmed based on the input clock speed in the driver. >=20 > The current code calculates these values based on the input clock speed a= nd > tries hard to meet the I2C bus timing requirements. This could result > non-optimal values with regarding to the bus speed. For example on Intel > BayTrail we get bus speed of 315.41kHz which is ~20% slower than we would > expect (400kHz) in fast mode (even though the timing requirements are met= ). >=20 > This patch makes it possible for the platform code to pass more optimal > HCNT/LCNT values to the core driver if they are known beforehand. If these > are not set we use the calculated and more conservative values. >=20 > Signed-off-by: Mika Westerberg Applied to for-next, thanks! --/3yNEOqWowh/8j+e Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJSHb56AAoJEBQN5MwUoCm2MzcP/3FhsmQ4yp+TJVbFnytWyl6O SKboOLuMIA2Q/Kdza69hdhMnTJleLRKAnogVqVM5iShZ/ega4RNr+nS5WS4Msl1R qYrvh70QOOpeb0Tt9zHqfqKvZrsY7u2H2m5IOichLJlnRpX2Lmbwo5dY7T4FszVD wWOWhJA+u13z3P/8uL3jAdxWSLMwgji+UC4cWR2MjHWePWscT3SYyawzJOuZWD5X rnkKt61JZYKy+035sjvKbDY1q60P6GS8/1nHAftsaEf8lxoqIgNTKR2TYUwSlD3U flY6FReu9rJa+Nnk9DcXPNqT4gcJ0WO3obl3puG7i5lkhbANN5utEgTAXRZvh8XE ZP6rcHqEViponCqv8S0Y0slEeGHF72H0alVkrzFehYcoBCG2YdBfCNqO7DlkTUrP 46MwtSqhw405FUn7Lk9GMHM/zZks2nXh4nluoNfRTBTnlfkKjo/yKhsrRDbMP9xh NCSNvaoNs/elWYBa+bXWpTuhnTqTc0760wpVCsxhYB3deeovaZ+WWwlSD4CcNITH ldolekOPKYbeTgivgtwRDvxcfG8GMqktOVeQBi7ulOoXv4rH9ySK2N4oG4UoatoO TJXkTF2GbpMzyYNS2P4mGPCARigM2V8juHF15uc9/RuzXBfc3JDIjetmutDzq5zI jPO2HQDNKRaD47usHi6x =vgcO -----END PGP SIGNATURE----- --/3yNEOqWowh/8j+e--