From: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org> To: Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>, Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Samuel Ortiz <sameo-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>, Emilio Lopez <emilio-0Z03zUJReD5OxF6Tv1QG9Q@public.gmane.org>, Mike Turquette <mturquette-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> Cc: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org>, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-serial-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Subject: [PATCH v4 5/6] serial: 8250_dw: Add support for deferred probing Date: Wed, 9 Jul 2014 15:54:38 +0800 [thread overview] Message-ID: <1404892479-12222-6-git-send-email-wens@csie.org> (raw) In-Reply-To: <1404892479-12222-1-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> The 8250_dw driver fails to probe if the specified clock isn't registered at probe time. Even if a clock frequency is given, the required clock might be gated because it wasn't properly enabled. This happened to me when the device is registered through DT, and the clock was part of an MFD, the PRCM found on A31 and A23 SoCs. Unlike core clocks that are registered with OF_CLK_DECLARE, which happen almost immediately after the kernel starts, the clocks are registered as sub-devices of the PRCM MFD platform device. Even though devices are registered in the order they are found in the DT, the drivers are registered in a different, arbitrary order. It is possible that the 8250_dw driver is registered, and thus associated with the device and probed, before the clock driver is registered and probed. 8250_dw then reports unable to get the clock, and fails. Without a working console, the kernel panics. This patch adds support for deferred probe handling for the clock and reset controller. Signed-off-by: Chen-Yu Tsai <wens-jdAy2FN1RRM@public.gmane.org> --- drivers/tty/serial/8250/8250_dw.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index cb1b3dc..d9eeed7 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -405,12 +405,16 @@ static int dw8250_probe(struct platform_device *pdev) data->usr_reg = DW_UART_USR; data->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER) + return -EPROBE_DEFER; if (!IS_ERR(data->clk)) { clk_prepare_enable(data->clk); uart.port.uartclk = clk_get_rate(data->clk); } data->rst = devm_reset_control_get_optional(&pdev->dev, NULL); + if (IS_ERR(data->rst) && PTR_ERR(data->rst) == -EPROBE_DEFER) + return -EPROBE_DEFER; if (!IS_ERR(data->rst)) reset_control_deassert(data->rst); -- 2.0.1
WARNING: multiple messages have this Message-ID (diff)
From: wens@csie.org (Chen-Yu Tsai) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 5/6] serial: 8250_dw: Add support for deferred probing Date: Wed, 9 Jul 2014 15:54:38 +0800 [thread overview] Message-ID: <1404892479-12222-6-git-send-email-wens@csie.org> (raw) In-Reply-To: <1404892479-12222-1-git-send-email-wens@csie.org> The 8250_dw driver fails to probe if the specified clock isn't registered at probe time. Even if a clock frequency is given, the required clock might be gated because it wasn't properly enabled. This happened to me when the device is registered through DT, and the clock was part of an MFD, the PRCM found on A31 and A23 SoCs. Unlike core clocks that are registered with OF_CLK_DECLARE, which happen almost immediately after the kernel starts, the clocks are registered as sub-devices of the PRCM MFD platform device. Even though devices are registered in the order they are found in the DT, the drivers are registered in a different, arbitrary order. It is possible that the 8250_dw driver is registered, and thus associated with the device and probed, before the clock driver is registered and probed. 8250_dw then reports unable to get the clock, and fails. Without a working console, the kernel panics. This patch adds support for deferred probe handling for the clock and reset controller. Signed-off-by: Chen-Yu Tsai <wens@csie.org> --- drivers/tty/serial/8250/8250_dw.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index cb1b3dc..d9eeed7 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -405,12 +405,16 @@ static int dw8250_probe(struct platform_device *pdev) data->usr_reg = DW_UART_USR; data->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(data->clk) && PTR_ERR(data->clk) == -EPROBE_DEFER) + return -EPROBE_DEFER; if (!IS_ERR(data->clk)) { clk_prepare_enable(data->clk); uart.port.uartclk = clk_get_rate(data->clk); } data->rst = devm_reset_control_get_optional(&pdev->dev, NULL); + if (IS_ERR(data->rst) && PTR_ERR(data->rst) == -EPROBE_DEFER) + return -EPROBE_DEFER; if (!IS_ERR(data->rst)) reset_control_deassert(data->rst); -- 2.0.1
next prev parent reply other threads:[~2014-07-09 7:54 UTC|newest] Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-07-09 7:54 [PATCH v4 0/6] ARM: sun8i: Support A23 PRCM clock and reset controllers Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [not found] ` <1404892479-12222-1-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-09 7:54 ` [PATCH v4 1/6] clk: sunxi: sun6i-apb0-gates: use bitmaps for valid gate indicies Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [not found] ` <1404892479-12222-2-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-15 6:53 ` Maxime Ripard 2014-07-15 6:53 ` Maxime Ripard 2014-07-09 7:54 ` [PATCH v4 2/6] clk: sunxi: sun6i-a31-apb0-gates: Add A23 APB0 support Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [not found] ` <1404892479-12222-3-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-15 6:53 ` Maxime Ripard 2014-07-15 6:53 ` Maxime Ripard 2014-07-09 7:54 ` [PATCH v4 3/6] mfd: sun6i-prcm: Add support for Allwinner A23 PRCM Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [not found] ` <1404892479-12222-4-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-10 9:37 ` Lee Jones 2014-07-10 9:37 ` Lee Jones 2014-07-15 6:55 ` Maxime Ripard 2014-07-15 6:55 ` Maxime Ripard 2014-07-15 7:11 ` Lee Jones 2014-07-15 7:11 ` Lee Jones 2014-07-09 7:54 ` [PATCH v4 4/6] serial: 8250_dw: Add optional reset control support Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [this message] 2014-07-09 7:54 ` [PATCH v4 5/6] serial: 8250_dw: Add support for deferred probing Chen-Yu Tsai [not found] ` <1404892479-12222-6-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-15 7:00 ` Maxime Ripard 2014-07-15 7:00 ` Maxime Ripard 2014-07-09 7:54 ` [PATCH v4 6/6] ARM: sun8i: Add PRCM clock and reset controller nodes to the DTSI Chen-Yu Tsai 2014-07-09 7:54 ` Chen-Yu Tsai [not found] ` <1404892479-12222-7-git-send-email-wens-jdAy2FN1RRM@public.gmane.org> 2014-07-10 5:20 ` fireescapefire-Re5JQEeQqe8AvxtiuMwx3w 2014-07-15 6:54 ` Maxime Ripard 2014-07-15 6:54 ` Maxime Ripard
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