From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from p15137414.pureserver.info (matrixvision.de [217.160.213.229]) by ozlabs.org (Postfix) with ESMTP id D3C3FDDDFB for ; Fri, 28 Nov 2008 02:43:46 +1100 (EST) Message-ID: <492EC031.9000802@matrix-vision.de> Date: Thu, 27 Nov 2008 16:43:45 +0100 From: Andre Schwarz MIME-Version: 1.0 To: Timur Tabi Subject: Re: i2c-mpc clocking scheme References: <492EB606.9020703@matrix-vision.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Timur Tabi schrieb: > On Thu, Nov 27, 2008 at 9:00 AM, Andre Schwarz > wrote: > >> All, >> >> is anybody working on some improvements regarding configurable I2C >> frequency inside the i2c-mpc driver ? >> >> If not - would anybody be intersted in getting this done, i.e. >> configurable via device tree ? >> > > Maybe I'm missing something, but U-Boot configures the I2C bus speed. > It does this because the algorithm is specific to the SOC itself. For > example, the 8544 is different from the 8548. It would be a mess to > duplicate this code in the kernel. > > You're right regarding U-Boot, but the i2c-mpc driver overwrites the "frequency divider register" on all chips. I'm not happy with a fixed 0x3f @ MPC5200 which results in 65kHz ... :-( Have a look at line 163 in drivers/i2c/busses/i2c-mpc.c MATRIX VISION GmbH, Talstraße 16, DE-71570 Oppenweiler - Registergericht: Amtsgericht Stuttgart, HRB 271090 Geschäftsführer: Gerhard Thullner, Werner Armingeon, Uwe Furtner