From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thor Thayer Subject: Re: [PATCH 1/4] Documentation: dt: serial: Add TX FIFO load size Date: Fri, 16 Sep 2016 15:47:41 -0500 Message-ID: <51b9cf7c-7989-b541-4eb1-9a38dc175284@opensource.altera.com> References: <1473351141-9239-1-git-send-email-tthayer@opensource.altera.com> <1473351141-9239-2-git-send-email-tthayer@opensource.altera.com> <20160916191908.GA30710@rob-hp-laptop> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160916191908.GA30710@rob-hp-laptop> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rob Herring Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, lftan-EIB2kfCEclfQT0dZR+AlfA@public.gmane.org, jslaby-IBi9RG/b67k@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org, andriy.shevchenko-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, anton.wuerfel-d40JDW7QUjc@public.gmane.org, phillip.raffeck-d40JDW7QUjc@public.gmane.org, yegorslists-gM/Ye1E23mwN+BqQ9rBEUg@public.gmane.org, matwey-TTlVxmypnbovJsYlp49lxw@public.gmane.org, mail-APzI5cXaD1zVlRWJc41N0YvC60bnQu0Y@public.gmane.org, peter.ujfalusi-l0cyMroinI0@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, dongsheng.wang-3arQi8VN3Tc@public.gmane.org, luis-HiykPkW1eAzzDCI4PIEvbQC/G2K4zDHf@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, tthayer.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, nios2-dev-g9ZBwUv/Ih/yUk5EbOjzuce+I+R0W71w@public.gmane.org List-Id: devicetree@vger.kernel.org Hi Rob, On 09/16/2016 02:19 PM, Rob Herring wrote: > On Thu, Sep 08, 2016 at 11:12:18AM -0500, tthayer-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org wrote: >> From: Thor Thayer >> >> Add the device tree bindings needed to support the TX FIFO >> load size. >> >> Signed-off-by: Thor Thayer >> --- >> Documentation/devicetree/bindings/serial/8250.txt | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt >> index f5561ac..93de5ef 100644 >> --- a/Documentation/devicetree/bindings/serial/8250.txt >> +++ b/Documentation/devicetree/bindings/serial/8250.txt >> @@ -45,6 +45,7 @@ Optional properties: >> - {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD >> line respectively. It will use specified GPIO instead of the peripheral >> function pin for the UART feature. If unsure, don't specify this property. >> +- tx-loadsz: the number of bytes that can be loaded into the TX FIFO. > > It seems you don't really need to know the loadsz, but just need the > threshold trigger level. So just use that directly. And please check if > any other UARTs have threshold properties. i.MX has programmable > thresholds. > > Rob > Yes, it is correct that I only really need the loadsz, but there is a tx-loadsz parameter in the uart_8250_port structure. Since there currently isn't a way to update the default value of tx-loadsz from device tree, I thought this would be useful for other 8250 UARTs as well. Yes, there are a couple of 8250 compatible UARTs that have programmable thresholds. The SC16654 and SC16C650 are 2 examples. However, I didn't see the programmable TX threshold implemented. I looked at the i.MX UARTs but I don't see a programmable threshold parameter in the bindings( Documentation/devicetree/bindings/serial/fsl-imx-uart.txt). I'm assuming you're saying that I should use the same binding names for this transmit threshold if they are available? Thank you for reviewing and for the comments. Thor -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html