| Message ID | 20170304130958.23655-1-james.hogan@imgtec.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
On Sat, Mar 4, 2017 at 3:09 PM, James Hogan <james.hogan@imgtec.com> wrote: > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > used") recently broke the 8250_dw driver on platforms which don't select > HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the > fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything > is fine but returns (valid) NULL clocks and 0 HZ clock rates. > > That 0 rate is written into the uartclk resulting in a crash at boot, > e.g. on Cavium Octeon III based UTM-8 we get something like this: > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON > ------------[ cut here ]------------ > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0 > ... > Call Trace: > ... > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > [<ffffffff811901a0>] register_console+0x1c8/0x418 > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 > ... > > The clock API is defined such that NULL is a valid clock handle so it > wouldn't be right to check explicitly for NULL. Instead treat a > clk_round_rate() return value of 0 as an error which prevents uartclk > being overwritten. > You forgot to add that it is dependent to Heiko's patch http://www.spinics.net/lists/linux-serial/msg25314.html Patch looks good to me and shouldn't bring any regression to Intel hardware (x86 is using clock framework). Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") > Signed-off-by: James Hogan <james.hogan@imgtec.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Jason Uy <jason.uy@broadcom.com> > Cc: Kefeng Wang <wangkefeng.wang@huawei.com> > Cc: Heiko Stuebner <heiko@sntech.de> > Cc: David Daney <david.daney@cavium.com> > Cc: Russell King <linux@armlinux.org.uk> > Cc: linux-serial@vger.kernel.org > Cc: linux-clk@vger.kernel.org > Cc: linux-mips@linux-mips.org > Cc: bcm-kernel-feedback-list@broadcom.com > --- > drivers/tty/serial/8250/8250_dw.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c > index 223ac234ddb2..e65808c482f1 100644 > --- a/drivers/tty/serial/8250/8250_dw.c > +++ b/drivers/tty/serial/8250/8250_dw.c > @@ -267,6 +267,8 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, > rate = clk_round_rate(d->clk, baud * 16); > if (rate < 0) > ret = rate; > + else if (rate == 0) > + ret = -ENOENT; > else > ret = clk_set_rate(d->clk, rate); > clk_prepare_enable(d->clk); > -- > 2.11.1 >
Am Samstag, 4. März 2017, 13:09:58 CET schrieb James Hogan: > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > used") recently broke the 8250_dw driver on platforms which don't select > HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the > fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything > is fine but returns (valid) NULL clocks and 0 HZ clock rates. > > That 0 rate is written into the uartclk resulting in a crash at boot, > e.g. on Cavium Octeon III based UTM-8 we get something like this: > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = > 25000000) is a OCTEON ------------[ cut here ]------------ > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 > uart_get_baud_rate+0xfc/0x1f0 ... > Call Trace: > ... > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > [<ffffffff811901a0>] register_console+0x1c8/0x418 > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 > ... > > The clock API is defined such that NULL is a valid clock handle so it > wouldn't be right to check explicitly for NULL. Instead treat a > clk_round_rate() return value of 0 as an error which prevents uartclk > being overwritten. > > Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > used") Signed-off-by: James Hogan <james.hogan@imgtec.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Jason Uy <jason.uy@broadcom.com> > Cc: Kefeng Wang <wangkefeng.wang@huawei.com> > Cc: Heiko Stuebner <heiko@sntech.de> > Cc: David Daney <david.daney@cavium.com> > Cc: Russell King <linux@armlinux.org.uk> > Cc: linux-serial@vger.kernel.org > Cc: linux-clk@vger.kernel.org > Cc: linux-mips@linux-mips.org > Cc: bcm-kernel-feedback-list@broadcom.com > --- > drivers/tty/serial/8250/8250_dw.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/tty/serial/8250/8250_dw.c > b/drivers/tty/serial/8250/8250_dw.c index 223ac234ddb2..e65808c482f1 100644 > --- a/drivers/tty/serial/8250/8250_dw.c > +++ b/drivers/tty/serial/8250/8250_dw.c > @@ -267,6 +267,8 @@ static void dw8250_set_termios(struct uart_port *p, > struct ktermios *termios, rate = clk_round_rate(d->clk, baud * 16); > if (rate < 0) > ret = rate; > + else if (rate == 0) > + ret = -ENOENT; > else > ret = clk_set_rate(d->clk, rate); > clk_prepare_enable(d->clk); Looks good Reviewed-by: Heiko Stuebner <heiko@sntech.de> -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, Mar 04, 2017 at 04:37:17PM +0200, Andy Shevchenko wrote: > On Sat, Mar 4, 2017 at 3:09 PM, James Hogan <james.hogan@imgtec.com> wrote: > > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > > used") recently broke the 8250_dw driver on platforms which don't select > > HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the > > fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything > > is fine but returns (valid) NULL clocks and 0 HZ clock rates. > > > > That 0 rate is written into the uartclk resulting in a crash at boot, > > e.g. on Cavium Octeon III based UTM-8 we get something like this: > > > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0 > > ... > > Call Trace: > > ... > > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > > [<ffffffff811901a0>] register_console+0x1c8/0x418 > > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 > > ... > > > > The clock API is defined such that NULL is a valid clock handle so it > > wouldn't be right to check explicitly for NULL. Instead treat a > > clk_round_rate() return value of 0 as an error which prevents uartclk > > being overwritten. > > > > You forgot to add that it is dependent to Heiko's patch > http://www.spinics.net/lists/linux-serial/msg25314.html Indeed I did. Sorry about that. > > Patch looks good to me and shouldn't bring any regression to Intel > hardware (x86 is using clock framework). > > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Thanks James
Looks good Reviewed-by: Jason Uy <jason.uy@broadcom.com> -----Original Message----- From: James Hogan [mailto:james.hogan@imgtec.com] Sent: March-06-17 2:16 AM To: Andy Shevchenko <andy.shevchenko@gmail.com> Cc: linux-kernel@vger.kernel.org; Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Andy Shevchenko <andriy.shevchenko@linux.intel.com>; Jason Uy <jason.uy@broadcom.com>; Kefeng Wang <wangkefeng.wang@huawei.com>; Heiko Stuebner <heiko@sntech.de>; David Daney <david.daney@cavium.com>; Russell King <linux@armlinux.org.uk>; linux-serial@vger.kernel.org; linux-clk@vger.kernel.org; linux-mips@linux-mips.org; bcm-kernel-feedback-list <bcm-kernel-feedback-list@broadcom.com> Subject: Re: [PATCH] serial: 8250_dw: Fix breakage when HAVE_CLK=n On Sat, Mar 04, 2017 at 04:37:17PM +0200, Andy Shevchenko wrote: > On Sat, Mar 4, 2017 at 3:09 PM, James Hogan <james.hogan@imgtec.com> > wrote: > > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control > > to be > > used") recently broke the 8250_dw driver on platforms which don't > > select HAVE_CLK, as dw8250_set_termios() gets confused by the > > behaviour of the fallback HAVE_CLK=n clock API in linux/clk.h which > > pretends everything is fine but returns (valid) NULL clocks and 0 HZ > > clock rates. > > > > That 0 rate is written into the uartclk resulting in a crash at > > boot, e.g. on Cavium Octeon III based UTM-8 we get something like this: > > > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, > > base_baud = 25000000) is a OCTEON ------------[ cut here > > ]------------ > > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 > > uart_get_baud_rate+0xfc/0x1f0 ... > > Call Trace: > > ... > > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > > [<ffffffff811901a0>] register_console+0x1c8/0x418 > > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 ... > > > > The clock API is defined such that NULL is a valid clock handle so > > it wouldn't be right to check explicitly for NULL. Instead treat a > > clk_round_rate() return value of 0 as an error which prevents > > uartclk being overwritten. > > > > You forgot to add that it is dependent to Heiko's patch > http://www.spinics.net/lists/linux-serial/msg25314.html Indeed I did. Sorry about that. > > Patch looks good to me and shouldn't bring any regression to Intel > hardware (x86 is using clock framework). > > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Thanks James -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Greg, On Sat, Mar 04, 2017 at 01:09:58PM +0000, James Hogan wrote: > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > used") recently broke the 8250_dw driver on platforms which don't select > HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the > fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything > is fine but returns (valid) NULL clocks and 0 HZ clock rates. > > That 0 rate is written into the uartclk resulting in a crash at boot, > e.g. on Cavium Octeon III based UTM-8 we get something like this: > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON > ------------[ cut here ]------------ > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0 > ... > Call Trace: > ... > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > [<ffffffff811901a0>] register_console+0x1c8/0x418 > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 > ... > > The clock API is defined such that NULL is a valid clock handle so it > wouldn't be right to check explicitly for NULL. Instead treat a > clk_round_rate() return value of 0 as an error which prevents uartclk > being overwritten. > > Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") > Signed-off-by: James Hogan <james.hogan@imgtec.com> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Cc: Jason Uy <jason.uy@broadcom.com> > Cc: Kefeng Wang <wangkefeng.wang@huawei.com> > Cc: Heiko Stuebner <heiko@sntech.de> > Cc: David Daney <david.daney@cavium.com> > Cc: Russell King <linux@armlinux.org.uk> > Cc: linux-serial@vger.kernel.org > Cc: linux-clk@vger.kernel.org > Cc: linux-mips@linux-mips.org > Cc: bcm-kernel-feedback-list@broadcom.com Any chance we could have this patch in v4.11-rc3? As Andy pointed out, it depends on Heiko's patch: https://www.spinics.net/lists/linux-serial/msg25483.html Thanks James
On Mon, Mar 13, 2017 at 11:14:07AM +0000, James Hogan wrote: > Hi Greg, > > On Sat, Mar 04, 2017 at 01:09:58PM +0000, James Hogan wrote: > > Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be > > used") recently broke the 8250_dw driver on platforms which don't select > > HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the > > fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything > > is fine but returns (valid) NULL clocks and 0 HZ clock rates. > > > > That 0 rate is written into the uartclk resulting in a crash at boot, > > e.g. on Cavium Octeon III based UTM-8 we get something like this: > > > > 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON > > ------------[ cut here ]------------ > > WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0 > > ... > > Call Trace: > > ... > > [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 > > [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 > > [<ffffffff8149c710>] uart_set_options+0xe8/0x190 > > [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 > > [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 > > [<ffffffff811901a0>] register_console+0x1c8/0x418 > > [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 > > [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 > > [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 > > ... > > > > The clock API is defined such that NULL is a valid clock handle so it > > wouldn't be right to check explicitly for NULL. Instead treat a > > clk_round_rate() return value of 0 as an error which prevents uartclk > > being overwritten. > > > > Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") > > Signed-off-by: James Hogan <james.hogan@imgtec.com> > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Cc: Jason Uy <jason.uy@broadcom.com> > > Cc: Kefeng Wang <wangkefeng.wang@huawei.com> > > Cc: Heiko Stuebner <heiko@sntech.de> > > Cc: David Daney <david.daney@cavium.com> > > Cc: Russell King <linux@armlinux.org.uk> > > Cc: linux-serial@vger.kernel.org > > Cc: linux-clk@vger.kernel.org > > Cc: linux-mips@linux-mips.org > > Cc: bcm-kernel-feedback-list@broadcom.com > > Any chance we could have this patch in v4.11-rc3? > > As Andy pointed out, it depends on Heiko's patch: > https://www.spinics.net/lists/linux-serial/msg25483.html Yes, will be queueing both up soon. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 223ac234ddb2..e65808c482f1 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -267,6 +267,8 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios, rate = clk_round_rate(d->clk, baud * 16); if (rate < 0) ret = rate; + else if (rate == 0) + ret = -ENOENT; else ret = clk_set_rate(d->clk, rate); clk_prepare_enable(d->clk);
Commit 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") recently broke the 8250_dw driver on platforms which don't select HAVE_CLK, as dw8250_set_termios() gets confused by the behaviour of the fallback HAVE_CLK=n clock API in linux/clk.h which pretends everything is fine but returns (valid) NULL clocks and 0 HZ clock rates. That 0 rate is written into the uartclk resulting in a crash at boot, e.g. on Cavium Octeon III based UTM-8 we get something like this: 1180000000800.serial: ttyS0 at MMIO 0x1180000000800 (irq = 41, base_baud = 25000000) is a OCTEON ------------[ cut here ]------------ WARNING: CPU: 2 PID: 1 at drivers/tty/serial/serial_core.c:441 uart_get_baud_rate+0xfc/0x1f0 ... Call Trace: ... [<ffffffff8149c2e4>] uart_get_baud_rate+0xfc/0x1f0 [<ffffffff814a5098>] serial8250_do_set_termios+0xb0/0x440 [<ffffffff8149c710>] uart_set_options+0xe8/0x190 [<ffffffff814a6cdc>] serial8250_console_setup+0x84/0x158 [<ffffffff814a11ec>] univ8250_console_setup+0x54/0x70 [<ffffffff811901a0>] register_console+0x1c8/0x418 [<ffffffff8149f004>] uart_add_one_port+0x434/0x4b0 [<ffffffff814a1af8>] serial8250_register_8250_port+0x2d8/0x440 [<ffffffff814aa620>] dw8250_probe+0x388/0x5e8 ... The clock API is defined such that NULL is a valid clock handle so it wouldn't be right to check explicitly for NULL. Instead treat a clk_round_rate() return value of 0 as an error which prevents uartclk being overwritten. Fixes: 6a171b299379 ("serial: 8250_dw: Allow hardware flow control to be used") Signed-off-by: James Hogan <james.hogan@imgtec.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Jason Uy <jason.uy@broadcom.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Heiko Stuebner <heiko@sntech.de> Cc: David Daney <david.daney@cavium.com> Cc: Russell King <linux@armlinux.org.uk> Cc: linux-serial@vger.kernel.org Cc: linux-clk@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: bcm-kernel-feedback-list@broadcom.com --- drivers/tty/serial/8250/8250_dw.c | 2 ++ 1 file changed, 2 insertions(+)