From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Machek Subject: Re: [PATCH 1/3] hvc_dcc: Fix bad code generation by marking assembly volatile Date: Sun, 2 Jan 2011 10:00:19 +0100 Message-ID: <20110102090019.GC32469@atrey.karlin.mff.cuni.cz> References: <1292649385-28771-1-git-send-email-sboyd@codeaurora.org> <1292875718-7980-1-git-send-email-sboyd@codeaurora.org> <1292875718-7980-2-git-send-email-sboyd@codeaurora.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ksp.mff.cuni.cz ([195.113.26.206]:51081 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750895Ab1ABJAU (ORCPT ); Sun, 2 Jan 2011 04:00:20 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-arm-msm-owner@vger.kernel.org List-Id: linux-arm-msm@vger.kernel.org To: Nicolas Pitre Cc: Stephen Boyd , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Tony Lindgren , Arnd Bergmann , Daniel Walker Hi! > > diff --git a/drivers/char/hvc_dcc.c b/drivers/char/hvc_dcc.c > > index 6470f63..155ec10 100644 > > --- a/drivers/char/hvc_dcc.c > > +++ b/drivers/char/hvc_dcc.c > > @@ -33,8 +33,7 @@ > > static inline u32 __dcc_getstatus(void) > > { > > u32 __ret; > > - > > - asm("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" > > + asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" > > : "=r" (__ret) : : "cc"); > > > > return __ret; Is volatile needed here? If __dcc_getstatus() return value is discarded, we want assembly discarded, right? > > @@ -58,7 +57,7 @@ static inline char __dcc_getchar(void) > > { > > char __c; > > > > - asm("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > > + asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > > : "=r" (__c)); > > > > return __c; Same here? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html From mboxrd@z Thu Jan 1 00:00:00 1970 From: pavel@ucw.cz (Pavel Machek) Date: Sun, 2 Jan 2011 10:00:19 +0100 Subject: [PATCH 1/3] hvc_dcc: Fix bad code generation by marking assembly volatile In-Reply-To: References: <1292649385-28771-1-git-send-email-sboyd@codeaurora.org> <1292875718-7980-1-git-send-email-sboyd@codeaurora.org> <1292875718-7980-2-git-send-email-sboyd@codeaurora.org> Message-ID: <20110102090019.GC32469@atrey.karlin.mff.cuni.cz> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi! > > diff --git a/drivers/char/hvc_dcc.c b/drivers/char/hvc_dcc.c > > index 6470f63..155ec10 100644 > > --- a/drivers/char/hvc_dcc.c > > +++ b/drivers/char/hvc_dcc.c > > @@ -33,8 +33,7 @@ > > static inline u32 __dcc_getstatus(void) > > { > > u32 __ret; > > - > > - asm("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" > > + asm volatile("mrc p14, 0, %0, c0, c1, 0 @ read comms ctrl reg" > > : "=r" (__ret) : : "cc"); > > > > return __ret; Is volatile needed here? If __dcc_getstatus() return value is discarded, we want assembly discarded, right? > > @@ -58,7 +57,7 @@ static inline char __dcc_getchar(void) > > { > > char __c; > > > > - asm("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > > + asm volatile("mrc p14, 0, %0, c0, c5, 0 @ read comms data reg" > > : "=r" (__c)); > > > > return __c; Same here? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html