From mboxrd@z Thu Jan 1 00:00:00 1970 From: Laurent Pinchart Date: Fri, 20 Nov 2015 14:47:19 +0000 Subject: Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Message-Id: <2396575.drsjxiqpHR@avalon> List-Id: References: <1447958344-836-1-git-send-email-geert+renesas@glider.be> <3383903.1R72kZGx62@avalon> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Geert Uytterhoeven Cc: Geert Uytterhoeven , Greg Kroah-Hartman , Simon Horman , Magnus Damm , Yoshinori Sato , "linux-serial@vger.kernel.org" , Linux-sh list , "linux-kernel@vger.kernel.org" Hi Geert, On Friday 20 November 2015 08:52:19 Geert Uytterhoeven wrote: > On Thu, Nov 19, 2015 at 10:04 PM, Laurent Pinchart wrote: > > On Thursday 19 November 2015 19:38:57 Geert Uytterhoeven wrote: > >> Refactor the clock and baud rate parameter code to ease adding support > >> for multiple clocks and baud rate generators later. > >> sci_scbrr_calc() now returns the bit rate error, so it can be compared > >> to the bit rate error for other baud rate generators. > >> > >> Signed-off-by: Geert Uytterhoeven > >> --- > >> > >> drivers/tty/serial/sh-sci.c | 176 +++++++++++++++++++++++++------------- > >> 1 file changed, 120 insertions(+), 56 deletions(-) > >> > >> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c > >> index 726c96d5a511c222..12800e52f41953dc 100644 > >> --- a/drivers/tty/serial/sh-sci.c > >> +++ b/drivers/tty/serial/sh-sci.c > >> @@ -2252,33 +2301,48 @@ static struct uart_ops sci_uart_ops = { > >> static int sci_init_clocks(struct sci_port *sci_port, struct device > >> *dev) > >> { > >> - /* Get the SCI functional clock. It's called "fck" on ARM. */ > >> - sci_port->fclk = devm_clk_get(dev, "fck"); > >> - if (PTR_ERR(sci_port->fclk) = -EPROBE_DEFER) > >> - return -EPROBE_DEFER; > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + const char *clk_names[] = { > >> + [SCI_FCK] = "fck", > >> + }; > >> + struct clk *clk; > >> + unsigned int i; > >> > >> - /* > >> - * But it used to be called "sci_ick", and we need to maintain DT > >> - * backward compatibility. > >> - */ > >> - sci_port->fclk = devm_clk_get(dev, "sci_ick"); > >> - if (PTR_ERR(sci_port->fclk) = -EPROBE_DEFER) > >> - return -EPROBE_DEFER; > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + for (i = 0; i < SCI_NUM_CLKS; i++) { > >> + clk = devm_clk_get(dev, clk_names[i]); > >> + if (PTR_ERR(clk) = -EPROBE_DEFER) > >> + return -EPROBE_DEFER; > >> > >> - /* > >> - * Not all SH platforms declare a clock lookup entry for SCI > >> devices, > >> - * in which case we need to get the global "peripheral_clk" clock. > >> - */ > >> - sci_port->fclk = devm_clk_get(dev, "peripheral_clk"); > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + if (IS_ERR(clk) && i = SCI_FCK) { > >> + /* > >> + * "fck" used to be called "sci_ick", and we need > >> to > >> + * maintain DT backward compatibility. > >> + */ > >> + clk = devm_clk_get(dev, "sci_ick"); > >> + if (PTR_ERR(clk) = -EPROBE_DEFER) > >> + return -EPROBE_DEFER; > >> + > >> + if (!IS_ERR(clk)) > >> + goto found; > >> + > >> + /* > >> + * Not all SH platforms declare a clock lookup > >> entry > >> + * for SCI devices, in which case we need to get > >> the > >> + * global "peripheral_clk" clock. > >> + */ > >> + clk = devm_clk_get(dev, "peripheral_clk"); > >> + if (!IS_ERR(clk)) > >> + goto found; > >> + > >> + dev_err(dev, "failed to get functional clock\n"); > >> + return PTR_ERR(clk); > >> + } > >> > >> - dev_err(dev, "failed to get functional clock\n"); > >> - return PTR_ERR(sci_port->fclk); > >> +found: > >> + if (!IS_ERR(clk)) > >> + dev_dbg(dev, "clk %u is %pC rate %pCr\n", i, clk, > >> clk); > >> + sci_port->clks[i] = IS_ERR(clk) ? NULL : clk; > > > > Isn't it an issue that we can't tell apart the case where there is no > > clock specified in DT and the case where we can't get the clock due to > > another error ? > > All failures here are for optional clocks. > If the real failure is that the clock wasn't specified (or misspelled) in > DT, it should have been detected during the integration phase. There could be cases where the clock is correctly specified in DT but can't be retrieved due to a runtime error. I suppose that's mostly theoretical in our case though. Maybe a dev_dbg for the error case could be useful too ? Can we tell the case where the clock is not specified in DT apart from other errors (-EPROBE_DEFER aside as that case is already handled) ? -- Regards, Laurent Pinchart From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760281AbbKTOrP (ORCPT ); Fri, 20 Nov 2015 09:47:15 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:34384 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751356AbbKTOrM (ORCPT ); Fri, 20 Nov 2015 09:47:12 -0500 From: Laurent Pinchart To: Geert Uytterhoeven Cc: Geert Uytterhoeven , Greg Kroah-Hartman , Simon Horman , Magnus Damm , Yoshinori Sato , "linux-serial@vger.kernel.org" , Linux-sh list , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Date: Fri, 20 Nov 2015 16:47:19 +0200 Message-ID: <2396575.drsjxiqpHR@avalon> User-Agent: KMail/4.14.8 (Linux/4.0.9-gentoo; KDE/4.14.8; x86_64; ; ) In-Reply-To: References: <1447958344-836-1-git-send-email-geert+renesas@glider.be> <3383903.1R72kZGx62@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Geert, On Friday 20 November 2015 08:52:19 Geert Uytterhoeven wrote: > On Thu, Nov 19, 2015 at 10:04 PM, Laurent Pinchart wrote: > > On Thursday 19 November 2015 19:38:57 Geert Uytterhoeven wrote: > >> Refactor the clock and baud rate parameter code to ease adding support > >> for multiple clocks and baud rate generators later. > >> sci_scbrr_calc() now returns the bit rate error, so it can be compared > >> to the bit rate error for other baud rate generators. > >> > >> Signed-off-by: Geert Uytterhoeven > >> --- > >> > >> drivers/tty/serial/sh-sci.c | 176 +++++++++++++++++++++++++------------- > >> 1 file changed, 120 insertions(+), 56 deletions(-) > >> > >> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c > >> index 726c96d5a511c222..12800e52f41953dc 100644 > >> --- a/drivers/tty/serial/sh-sci.c > >> +++ b/drivers/tty/serial/sh-sci.c > >> @@ -2252,33 +2301,48 @@ static struct uart_ops sci_uart_ops = { > >> static int sci_init_clocks(struct sci_port *sci_port, struct device > >> *dev) > >> { > >> - /* Get the SCI functional clock. It's called "fck" on ARM. */ > >> - sci_port->fclk = devm_clk_get(dev, "fck"); > >> - if (PTR_ERR(sci_port->fclk) == -EPROBE_DEFER) > >> - return -EPROBE_DEFER; > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + const char *clk_names[] = { > >> + [SCI_FCK] = "fck", > >> + }; > >> + struct clk *clk; > >> + unsigned int i; > >> > >> - /* > >> - * But it used to be called "sci_ick", and we need to maintain DT > >> - * backward compatibility. > >> - */ > >> - sci_port->fclk = devm_clk_get(dev, "sci_ick"); > >> - if (PTR_ERR(sci_port->fclk) == -EPROBE_DEFER) > >> - return -EPROBE_DEFER; > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + for (i = 0; i < SCI_NUM_CLKS; i++) { > >> + clk = devm_clk_get(dev, clk_names[i]); > >> + if (PTR_ERR(clk) == -EPROBE_DEFER) > >> + return -EPROBE_DEFER; > >> > >> - /* > >> - * Not all SH platforms declare a clock lookup entry for SCI > >> devices, > >> - * in which case we need to get the global "peripheral_clk" clock. > >> - */ > >> - sci_port->fclk = devm_clk_get(dev, "peripheral_clk"); > >> - if (!IS_ERR(sci_port->fclk)) > >> - return 0; > >> + if (IS_ERR(clk) && i == SCI_FCK) { > >> + /* > >> + * "fck" used to be called "sci_ick", and we need > >> to > >> + * maintain DT backward compatibility. > >> + */ > >> + clk = devm_clk_get(dev, "sci_ick"); > >> + if (PTR_ERR(clk) == -EPROBE_DEFER) > >> + return -EPROBE_DEFER; > >> + > >> + if (!IS_ERR(clk)) > >> + goto found; > >> + > >> + /* > >> + * Not all SH platforms declare a clock lookup > >> entry > >> + * for SCI devices, in which case we need to get > >> the > >> + * global "peripheral_clk" clock. > >> + */ > >> + clk = devm_clk_get(dev, "peripheral_clk"); > >> + if (!IS_ERR(clk)) > >> + goto found; > >> + > >> + dev_err(dev, "failed to get functional clock\n"); > >> + return PTR_ERR(clk); > >> + } > >> > >> - dev_err(dev, "failed to get functional clock\n"); > >> - return PTR_ERR(sci_port->fclk); > >> +found: > >> + if (!IS_ERR(clk)) > >> + dev_dbg(dev, "clk %u is %pC rate %pCr\n", i, clk, > >> clk); > >> + sci_port->clks[i] = IS_ERR(clk) ? NULL : clk; > > > > Isn't it an issue that we can't tell apart the case where there is no > > clock specified in DT and the case where we can't get the clock due to > > another error ? > > All failures here are for optional clocks. > If the real failure is that the clock wasn't specified (or misspelled) in > DT, it should have been detected during the integration phase. There could be cases where the clock is correctly specified in DT but can't be retrieved due to a runtime error. I suppose that's mostly theoretical in our case though. Maybe a dev_dbg for the error case could be useful too ? Can we tell the case where the clock is not specified in DT apart from other errors (-EPROBE_DEFER aside as that case is already handled) ? -- Regards, Laurent Pinchart