From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kevin Hilman Subject: Re: [PATCH v2 1/1] omap: serial: fix non-empty uart fifo read abort Date: Tue, 17 Nov 2009 16:30:39 -0800 Message-ID: <87iqd8fzdc.fsf@deeprootsystems.com> References: <1258501151-30866-1-git-send-email-vikram.pandita@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-qy0-f174.google.com ([209.85.221.174]:45303 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755105AbZKRAag (ORCPT ); Tue, 17 Nov 2009 19:30:36 -0500 Received: by qyk4 with SMTP id 4so367114qyk.33 for ; Tue, 17 Nov 2009 16:30:42 -0800 (PST) In-Reply-To: <1258501151-30866-1-git-send-email-vikram.pandita@ti.com> (Vikram Pandita's message of "Tue\, 17 Nov 2009 17\:39\:11 -0600") Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Vikram Pandita Cc: linux-omap@vger.kernel.org, Alan Cox Vikram Pandita writes: > OMAP3630 and OMAP4430 UART IP blocks have a restriction wrt RX FIFO. > Empty RX fifo read causes an abort. OMAP1/2/3 do not have this restriction. > > Overrigt the default 8250 read handler: mem_serial_in() > by a custom handler: serial_in_8250() > > serial_in_8250() makes sure that RX fifo is not read when empty, > on omap4 and 3630 silicons only > > tested on zoom3(3630) board > > Signed-off-by: Vikram Pandita > Cc: Alan Cox > --- > v1: initial implementation > http://patchwork.kernel.org/patch/60785/ > http://patchwork.kernel.org/patch/60786/ > > v2: incorporate review comments from Alan Cox > http://patchwork.kernel.org/patch/60785/ > No 8250 driver change required now > > arch/arm/mach-omap2/serial.c | 28 ++++++++++++++++++++++++++++ > 1 files changed, 28 insertions(+), 0 deletions(-) > > diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c > index 2e17b57..362cb82 100644 > --- a/arch/arm/mach-omap2/serial.c > +++ b/arch/arm/mach-omap2/serial.c > @@ -71,6 +71,30 @@ struct omap_uart_state { > > static LIST_HEAD(uart_list); > > +static struct omap_uart_state omap_uart[]; > +static inline unsigned int serial_read_reg(struct plat_serial8250_port *, int); > + > +/* > + * Overrigt the default 8250 read handler: mem_serial_in() > + * Empty RX fifo read causes an abort on omap3630 and omap4 > + * This function makes sure that an empty rx fifo is not read on these silicons > + * (OMAP1/2/3 are not affected) > + */ > +static unsigned int serial_in_8250(struct uart_port *up, int offset) > +{ > + /* Do not read empty UART fifo on omap3630/44xx */ > + if ((UART_RX == offset) && > + (cpu_is_omap3630() || cpu_is_omap44xx())) { Rather than the cpu_is_* here, why not just override the function for these platforms and leave the default for 34xx/35xx. Kevin