From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Pringlemeir Subject: Re: fsl_lpuart/VF610: Division by zero. Date: Mon, 28 Jul 2014 18:38:39 -0400 Message-ID: <87zjftaz2o.fsf@nbsps.com> References: <87ha256q8l.fsf@nbsps.com> <87d2ct6p77.fsf@nbsps.com> <1aa4c71fa7441f217f33e7be9a8fa1b9@agner.ch> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from 71-19-161-253.dedicated.allstream.net ([71.19.161.253]:51715 "EHLO nsa.nbspaymentsolutions.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751425AbaG1WvB (ORCPT ); Mon, 28 Jul 2014 18:51:01 -0400 In-Reply-To: <1aa4c71fa7441f217f33e7be9a8fa1b9@agner.ch> (Stefan Agner's message of "Sat, 26 Jul 2014 14:08:38 +0200") Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Stefan Agner Cc: Yuan Yao , linux-serial@vger.kernel.org, Greg Kroah-Hartman , linux-arm-kernel@lists.infradead.org On 26 Jul 2014, stefan@agner.ch wrote: > Hi Bill, > > Am 2014-07-26 00:36, schrieb Bill Pringlemeir: >> On 25 Jul 2014, bpringlemeir@nbsps.com wrote: > >>> I looked at the vmlinux objdump and it is here, >>> >>> static int lpuart_dma_rx_request(struct uart_port *port) >>> { >>> ... >>> sport->dma_rx_timeout = (sport->port.timeout - HZ / 50) * >>> FSL_UART_RX_DMA_BUFFER_SIZE * 3 / >>> sport->rxfifo_size / 2; >>> >>> The variable 'sport->rxfifo_size' is set in lpuart_setup_watermark() >>> and this is called after lpuart_dma_rx_request() in >>> lpuart_startup(). > I observed this division by zero too, I recently sent a patch for > that. > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268772.html > Greg already added that to his tty-next tree: > https://git.kernel.org/cgit/linux/kernel/git/gregkh/tty.git/tree/drivers/tty/serial/fsl_lpuart.c?h=tty-next#n1309 > I also observed that DMA did not work yet, hence I a created a second > patch: > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268773.html > > But eDMA in general was broken too, this patch solved that, hence you > might want apply that patch too: > http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/268199.html > > All patches are lined up for 3.17, so things should be smooth from > that release on. Thanks, I applied all three patches to the arm-soc 'for-next' and now the serial ports seems to be working. I am using the Tower board and they have a 'TWR-SER2' card. http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=TWR-SER2 Unfortunately, the IOMUX conflicts with the Audio daughter-board in vf610-twr.dts. The I/O conflicts are, VF610_PAD_PTB6__FTM0_CH6 VF610_PAD_PTB7__FTM0_CH7 versus VF610_PAD_PTB6__UART2_TX VF610_PAD_PTB7__UART2_RX Below are the DT changes to get two 'ttyLP' working with the Tower System which probably will never apply cleanly, but are just meant for reference. --- a/arch/arm/boot/dts/vf610-twr.dts +++ b/arch/arm/boot/dts/vf610-twr.dts @@ -58,7 +59,7 @@ regulator-max-microvolt = <3300000>; }; }; - +/* sound { compatible = "simple-audio-card"; simple-audio-card,format = "i2s"; @@ -87,6 +88,7 @@ bitclock-master; }; }; +*/ }; &adc0 { @@ -241,7 +243,7 @@ }; - +/* pinctrl_pwm0: pwm0grp { fsl,pins = < VF610_PAD_PTB0__FTM0_CH0 0x1582 @@ -252,7 +254,7 @@ VF610_PAD_PTB7__FTM0_CH7 0x1582 >; }; - +*/ pinctrl_sai2: sai2grp { fsl,pins = < VF610_PAD_PTA16__SAI2_TX_BCLK 0x02ed @@ -271,6 +273,13 @@ VF610_PAD_PTB5__UART1_RX 0x21a1 >; }; + + pinctrl_uart2: uart2grp { + fsl,pins = < + VF610_PAD_PTB6__UART2_TX 0x21a2 + VF610_PAD_PTB7__UART2_RX 0x21a1 + >; + }; }; }; @@ -284,21 +293,31 @@ status = "okay"; }; +/* &pwm0 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_pwm0>; status = "okay"; }; - &sai2 { #sound-dai-cells = <0>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_sai2>; status = "okay"; }; - +*/ +&uart2 { + pinctrl-names = "default"; + pinctrl-0 = <&pinctrl_uart2>; + status = "okay"; +}; The standard jumpers on the Tower will either route ttyLP1 to the 'USB' or to the 'serial board'; ttyLP2 will be the opposite with the 'serial board' or the 'USB'. Thanks again. I should have read the linux-arm list more diligently. Bill Pringlemeir.