From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E034FC433F5 for ; Thu, 25 Nov 2021 17:46:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243132AbhKYRuG (ORCPT ); Thu, 25 Nov 2021 12:50:06 -0500 Received: from mail.kernel.org ([198.145.29.99]:55534 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243657AbhKYRsG (ORCPT ); Thu, 25 Nov 2021 12:48:06 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 181B26112E; Thu, 25 Nov 2021 17:44:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1637862294; bh=4Vn35Pzp4d6yF3CRQ4ZWZdQJ/igkvJCi+qeqXauwy84=; h=Subject:To:From:Date:From; b=nRH9JCxWXRMpHcIB7O2Fn3BFgMukryntYQM74RDyGVsILQeeoJtL1HTWbqZVyyr6O Hi2MgNdGYYolXzolj1zU1h8Rz4xwzFwmWlmVuZ8ElmdejVfb4udofPVDwXIlWFPiqR T83cVpJrtB6QpNPdacYIwWhBVCNXoAXdAMItV/6E= Subject: patch "serial: 8250_pci: rewrite pericom_do_set_divisor()" added to tty-linus To: jay.dolan@accesio.com, andriy.shevchenko@linux.intel.com, gregkh@linuxfoundation.org, stable@vger.kernel.org From: Date: Thu, 25 Nov 2021 18:42:29 +0100 Message-ID: <1637862149167146@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled serial: 8250_pci: rewrite pericom_do_set_divisor() to my tty git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git in the tty-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From bb1201d4b38ec67bd9a871cf86b0cc10f28b15b5 Mon Sep 17 00:00:00 2001 From: Jay Dolan Date: Mon, 22 Nov 2021 14:06:04 +0200 Subject: serial: 8250_pci: rewrite pericom_do_set_divisor() Have pericom_do_set_divisor() use the uartclk instead of a hard coded value to work with different speed crystals. Tested with 14.7456 and 24 MHz crystals. Have pericom_do_set_divisor() always calculate the divisor rather than call serial8250_do_set_divisor() for rates below baud_base. Do not write registers or call serial8250_do_set_divisor() if valid divisors could not be found. Fixes: 6bf4e42f1d19 ("serial: 8250: Add support for higher baud rates to Pericom chips") Cc: stable Signed-off-by: Jay Dolan Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20211122120604.3909-3-andriy.shevchenko@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_pci.c | 30 +++++++++++++++++------------- 1 file changed, 17 insertions(+), 13 deletions(-) diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c index b793d848aeb6..60f8fffdfd77 100644 --- a/drivers/tty/serial/8250/8250_pci.c +++ b/drivers/tty/serial/8250/8250_pci.c @@ -1324,29 +1324,33 @@ pericom_do_set_divisor(struct uart_port *port, unsigned int baud, { int scr; int lcr; - int actual_baud; - int tolerance; - for (scr = 5 ; scr <= 15 ; scr++) { - actual_baud = 921600 * 16 / scr; - tolerance = actual_baud / 50; + for (scr = 16; scr > 4; scr--) { + unsigned int maxrate = port->uartclk / scr; + unsigned int divisor = max(maxrate / baud, 1U); + int delta = maxrate / divisor - baud; - if ((baud < actual_baud + tolerance) && - (baud > actual_baud - tolerance)) { + if (baud > maxrate + baud / 50) + continue; + if (delta > baud / 50) + divisor++; + + if (divisor > 0xffff) + continue; + + /* Update delta due to possible divisor change */ + delta = maxrate / divisor - baud; + if (abs(delta) < baud / 50) { lcr = serial_port_in(port, UART_LCR); serial_port_out(port, UART_LCR, lcr | 0x80); - - serial_port_out(port, UART_DLL, 1); - serial_port_out(port, UART_DLM, 0); + serial_port_out(port, UART_DLL, divisor & 0xff); + serial_port_out(port, UART_DLM, divisor >> 8 & 0xff); serial_port_out(port, 2, 16 - scr); serial_port_out(port, UART_LCR, lcr); return; - } else if (baud > actual_baud) { - break; } } - serial8250_do_set_divisor(port, baud, quot, quot_frac); } static int pci_pericom_setup(struct serial_private *priv, const struct pciserial_board *board, -- 2.34.0