From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932818AbbJPPlO (ORCPT ); Fri, 16 Oct 2015 11:41:14 -0400 Received: from mail-lb0-f170.google.com ([209.85.217.170]:33233 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752644AbbJPPk4 (ORCPT ); Fri, 16 Oct 2015 11:40:56 -0400 Date: Fri, 16 Oct 2015 17:40:58 +0200 From: Johan Hovold To: Konstantin Shkolnyy Cc: Johan Hovold , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] USB: serial: cp210x: Workaround for cp2108 failure due to GET_LINE_CTL bug Message-ID: <20151016154058.GB32032@localhost> References: <1444951411-19799-1-git-send-email-konstantin.shkolnyy@gmail.com> <20151016132736.GD30216@localhost> <20151016152700.GA32032@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 16, 2015 at 10:39:13AM -0500, Konstantin Shkolnyy wrote: > On Fri, Oct 16, 2015 at 10:27 AM, Johan Hovold wrote: > > On Fri, Oct 16, 2015 at 10:11:12AM -0500, Konstantin Shkolnyy wrote: > >> On Fri, Oct 16, 2015 at 8:27 AM, Johan Hovold wrote: > >> > On Thu, Oct 15, 2015 at 06:23:31PM -0500, Konstantin Shkolnyy wrote: > >> >> cp2108 GET_LINE_CTL returns the 16-bit value with the 2 bytes swapped. > >> >> However, SET_LINE_CTL functions properly. When the driver tries to modify > >> >> the register, it reads it, modifies some bits and writes back. Because the > >> >> read bytes were swapped, this often results in an invalid value to be written. > >> >> In turn, this causes cp2108 respond with a stall. The stall sometimes doesn't > >> >> clear properly and cp2108 starts responding to following valid commands also > >> >> with stalls, effectively failing. > >> > > >> > That sounds weird. Are you saying that all or only some cp2108 devices > >> > would be affected by this? And only for the line-control register? > >> > >> The bug exists in all current cp2108 devices and affects only > >> GET_LINE_CTL. But it may be fixed in a future revision. > > > > Ok, have you some kind of confirmation from silabs on this already? > > I work for SiLabs. Heh. :) Johan