* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 5:09 ` Masahiro Yamada 0 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-21 5:09 UTC (permalink / raw) To: devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Hi. I think there exist two ways to specify the console port and baudrate. [1] Specify console in bootargs chosen { bootargs = "console=ttyS0,115200"; }; [2] Specify stdout-path chosen { stdout-path = "serial0:115200n8"; }; Now I have both in my DTS, but it is redundant. So, I want to select either [1] or [2]. Which is a preferable way? Thanks, -- Best Regards Masahiro Yamada -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 5:09 ` Masahiro Yamada 0 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-21 5:09 UTC (permalink / raw) To: linux-arm-kernel Hi. I think there exist two ways to specify the console port and baudrate. [1] Specify console in bootargs chosen { bootargs = "console=ttyS0,115200"; }; [2] Specify stdout-path chosen { stdout-path = "serial0:115200n8"; }; Now I have both in my DTS, but it is redundant. So, I want to select either [1] or [2]. Which is a preferable way? Thanks, -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 5:09 ` Masahiro Yamada @ 2015-10-21 7:43 ` Arnd Bergmann -1 siblings, 0 replies; 22+ messages in thread From: Arnd Bergmann @ 2015-10-21 7:43 UTC (permalink / raw) To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r Cc: Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-serial-u79uwXL29TY76Z2rM5mHXA On Wednesday 21 October 2015 14:09:42 Masahiro Yamada wrote: > > I think there exist two ways to specify the console port and baudrate. > > > [1] Specify console in bootargs > > chosen { > bootargs = "console=ttyS0,115200"; > }; > > > [2] Specify stdout-path > > chosen { > stdout-path = "serial0:115200n8"; > }; > > > > Now I have both in my DTS, but it is redundant. > > So, I want to select either [1] or [2]. > > > Which is a preferable way? > stdout-path is better. It took us a while to get that implemented on arm32, but now that it works, we should all use it. Arnd -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 7:43 ` Arnd Bergmann 0 siblings, 0 replies; 22+ messages in thread From: Arnd Bergmann @ 2015-10-21 7:43 UTC (permalink / raw) To: linux-arm-kernel On Wednesday 21 October 2015 14:09:42 Masahiro Yamada wrote: > > I think there exist two ways to specify the console port and baudrate. > > > [1] Specify console in bootargs > > chosen { > bootargs = "console=ttyS0,115200"; > }; > > > [2] Specify stdout-path > > chosen { > stdout-path = "serial0:115200n8"; > }; > > > > Now I have both in my DTS, but it is redundant. > > So, I want to select either [1] or [2]. > > > Which is a preferable way? > stdout-path is better. It took us a while to get that implemented on arm32, but now that it works, we should all use it. Arnd ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 5:09 ` Masahiro Yamada @ 2015-10-21 8:58 ` Sudeep Holla -1 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 8:58 UTC (permalink / raw) To: Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Cc: Sudeep Holla On 21/10/15 06:09, Masahiro Yamada wrote: > Hi. > > > I think there exist two ways to specify the console port and baudrate. > > > [1] Specify console in bootargs > > chosen { > bootargs = "console=ttyS0,115200"; > }; > > > [2] Specify stdout-path > > chosen { > stdout-path = "serial0:115200n8"; This will work for even early/boot console, so this is better than option [1] -- Regards, Sudeep -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 8:58 ` Sudeep Holla 0 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 8:58 UTC (permalink / raw) To: linux-arm-kernel On 21/10/15 06:09, Masahiro Yamada wrote: > Hi. > > > I think there exist two ways to specify the console port and baudrate. > > > [1] Specify console in bootargs > > chosen { > bootargs = "console=ttyS0,115200"; > }; > > > [2] Specify stdout-path > > chosen { > stdout-path = "serial0:115200n8"; This will work for even early/boot console, so this is better than option [1] -- Regards, Sudeep ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 8:58 ` Sudeep Holla @ 2015-10-21 12:46 ` Peter Hurley -1 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 12:46 UTC (permalink / raw) To: Sudeep Holla, Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA On 10/21/2015 04:58 AM, Sudeep Holla wrote: > On 21/10/15 06:09, Masahiro Yamada wrote: >> I think there exist two ways to specify the console port and baudrate. >> >> >> [1] Specify console in bootargs >> >> chosen { >> bootargs = "console=ttyS0,115200"; >> }; >> >> >> [2] Specify stdout-path >> >> chosen { >> stdout-path = "serial0:115200n8"; > > This will work for even early/boot console, so this is better than > option [1] Be aware that options specified via /chosen/stdout-path are currently ignored by earlycon. There were some hiccups getting the initial support upstream; when 4.4 hits mainline, I'll resubmit my series that implements the of_serial i/o properties and options passthrough to earlycon setup. Regards, Peter Hurley -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 12:46 ` Peter Hurley 0 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 12:46 UTC (permalink / raw) To: linux-arm-kernel On 10/21/2015 04:58 AM, Sudeep Holla wrote: > On 21/10/15 06:09, Masahiro Yamada wrote: >> I think there exist two ways to specify the console port and baudrate. >> >> >> [1] Specify console in bootargs >> >> chosen { >> bootargs = "console=ttyS0,115200"; >> }; >> >> >> [2] Specify stdout-path >> >> chosen { >> stdout-path = "serial0:115200n8"; > > This will work for even early/boot console, so this is better than > option [1] Be aware that options specified via /chosen/stdout-path are currently ignored by earlycon. There were some hiccups getting the initial support upstream; when 4.4 hits mainline, I'll resubmit my series that implements the of_serial i/o properties and options passthrough to earlycon setup. Regards, Peter Hurley ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 12:46 ` Peter Hurley @ 2015-10-21 12:54 ` Sudeep Holla -1 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 12:54 UTC (permalink / raw) To: Peter Hurley, Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Cc: Sudeep Holla On 21/10/15 13:46, Peter Hurley wrote: > On 10/21/2015 04:58 AM, Sudeep Holla wrote: >> On 21/10/15 06:09, Masahiro Yamada wrote: >>> I think there exist two ways to specify the console port and baudrate. >>> >>> >>> [1] Specify console in bootargs >>> >>> chosen { >>> bootargs = "console=ttyS0,115200"; >>> }; >>> >>> >>> [2] Specify stdout-path >>> >>> chosen { >>> stdout-path = "serial0:115200n8"; >> >> This will work for even early/boot console, so this is better than >> option [1] > > Be aware that options specified via /chosen/stdout-path are > currently ignored by earlycon. There were some hiccups getting the > initial support upstream; when 4.4 hits mainline, I'll resubmit > my series that implements the of_serial i/o properties and > options passthrough to earlycon setup. > Yes I am aware of that. IIUC it's in -next now and works fine for me. But having stdout-path in the DTS won't hinder normal console in anyway. So I prefer it even without the patch you are referring(to support early console parsing stdout-path) -- Regards, Sudeep -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 12:54 ` Sudeep Holla 0 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 12:54 UTC (permalink / raw) To: linux-arm-kernel On 21/10/15 13:46, Peter Hurley wrote: > On 10/21/2015 04:58 AM, Sudeep Holla wrote: >> On 21/10/15 06:09, Masahiro Yamada wrote: >>> I think there exist two ways to specify the console port and baudrate. >>> >>> >>> [1] Specify console in bootargs >>> >>> chosen { >>> bootargs = "console=ttyS0,115200"; >>> }; >>> >>> >>> [2] Specify stdout-path >>> >>> chosen { >>> stdout-path = "serial0:115200n8"; >> >> This will work for even early/boot console, so this is better than >> option [1] > > Be aware that options specified via /chosen/stdout-path are > currently ignored by earlycon. There were some hiccups getting the > initial support upstream; when 4.4 hits mainline, I'll resubmit > my series that implements the of_serial i/o properties and > options passthrough to earlycon setup. > Yes I am aware of that. IIUC it's in -next now and works fine for me. But having stdout-path in the DTS won't hinder normal console in anyway. So I prefer it even without the patch you are referring(to support early console parsing stdout-path) -- Regards, Sudeep ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 12:54 ` Sudeep Holla @ 2015-10-21 13:02 ` Peter Hurley -1 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 13:02 UTC (permalink / raw) To: Sudeep Holla, Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA On 10/21/2015 08:54 AM, Sudeep Holla wrote: > > > On 21/10/15 13:46, Peter Hurley wrote: >> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>> I think there exist two ways to specify the console port and baudrate. >>>> >>>> >>>> [1] Specify console in bootargs >>>> >>>> chosen { >>>> bootargs = "console=ttyS0,115200"; >>>> }; >>>> >>>> >>>> [2] Specify stdout-path >>>> >>>> chosen { >>>> stdout-path = "serial0:115200n8"; >>> >>> This will work for even early/boot console, so this is better than >>> option [1] >> >> Be aware that options specified via /chosen/stdout-path are >> currently ignored by earlycon. There were some hiccups getting the >> initial support upstream; when 4.4 hits mainline, I'll resubmit >> my series that implements the of_serial i/o properties and >> options passthrough to earlycon setup. >> > > Yes I am aware of that. The others to which my email was addressed might not know that. > IIUC it's in -next now and works fine for me. Well, the fix in -next doesn't actually do anything wrt earlycon baud rate; those changes were part of a larger series that depends on the fix in -next. Regards, Peter Hurley > But having stdout-path in the DTS won't hinder normal console in anyway. > So I prefer it even without the patch you are referring(to support early > console parsing stdout-path) -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 13:02 ` Peter Hurley 0 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 13:02 UTC (permalink / raw) To: linux-arm-kernel On 10/21/2015 08:54 AM, Sudeep Holla wrote: > > > On 21/10/15 13:46, Peter Hurley wrote: >> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>> I think there exist two ways to specify the console port and baudrate. >>>> >>>> >>>> [1] Specify console in bootargs >>>> >>>> chosen { >>>> bootargs = "console=ttyS0,115200"; >>>> }; >>>> >>>> >>>> [2] Specify stdout-path >>>> >>>> chosen { >>>> stdout-path = "serial0:115200n8"; >>> >>> This will work for even early/boot console, so this is better than >>> option [1] >> >> Be aware that options specified via /chosen/stdout-path are >> currently ignored by earlycon. There were some hiccups getting the >> initial support upstream; when 4.4 hits mainline, I'll resubmit >> my series that implements the of_serial i/o properties and >> options passthrough to earlycon setup. >> > > Yes I am aware of that. The others to which my email was addressed might not know that. > IIUC it's in -next now and works fine for me. Well, the fix in -next doesn't actually do anything wrt earlycon baud rate; those changes were part of a larger series that depends on the fix in -next. Regards, Peter Hurley > But having stdout-path in the DTS won't hinder normal console in anyway. > So I prefer it even without the patch you are referring(to support early > console parsing stdout-path) ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 13:02 ` Peter Hurley @ 2015-10-21 13:06 ` Sudeep Holla -1 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 13:06 UTC (permalink / raw) To: Peter Hurley, Masahiro Yamada, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Cc: Sudeep Holla On 21/10/15 14:02, Peter Hurley wrote: > On 10/21/2015 08:54 AM, Sudeep Holla wrote: >> On 21/10/15 13:46, Peter Hurley wrote: [..] >>> Be aware that options specified via /chosen/stdout-path are >>> currently ignored by earlycon. There were some hiccups getting the >>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>> my series that implements the of_serial i/o properties and >>> options passthrough to earlycon setup. >>> >> >> Yes I am aware of that. > > The others to which my email was addressed might not know that. > True, good that you pointed it out. >> IIUC it's in -next now and works fine for me. > > Well, the fix in -next doesn't actually do anything wrt earlycon baud > rate; those changes were part of a larger series that depends on > the fix in -next. > Ah ok. -- Regards, Sudeep -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 13:06 ` Sudeep Holla 0 siblings, 0 replies; 22+ messages in thread From: Sudeep Holla @ 2015-10-21 13:06 UTC (permalink / raw) To: linux-arm-kernel On 21/10/15 14:02, Peter Hurley wrote: > On 10/21/2015 08:54 AM, Sudeep Holla wrote: >> On 21/10/15 13:46, Peter Hurley wrote: [..] >>> Be aware that options specified via /chosen/stdout-path are >>> currently ignored by earlycon. There were some hiccups getting the >>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>> my series that implements the of_serial i/o properties and >>> options passthrough to earlycon setup. >>> >> >> Yes I am aware of that. > > The others to which my email was addressed might not know that. > True, good that you pointed it out. >> IIUC it's in -next now and works fine for me. > > Well, the fix in -next doesn't actually do anything wrt earlycon baud > rate; those changes were part of a larger series that depends on > the fix in -next. > Ah ok. -- Regards, Sudeep ^ permalink raw reply [flat|nested] 22+ messages in thread
* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 12:46 ` Peter Hurley @ 2015-10-21 15:38 ` Masahiro Yamada -1 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-21 15:38 UTC (permalink / raw) To: Peter Hurley Cc: Sudeep Holla, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Hi Peter. 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: > On 10/21/2015 04:58 AM, Sudeep Holla wrote: >> On 21/10/15 06:09, Masahiro Yamada wrote: >>> I think there exist two ways to specify the console port and baudrate. >>> >>> >>> [1] Specify console in bootargs >>> >>> chosen { >>> bootargs = "console=ttyS0,115200"; >>> }; >>> >>> >>> [2] Specify stdout-path >>> >>> chosen { >>> stdout-path = "serial0:115200n8"; >> >> This will work for even early/boot console, so this is better than >> option [1] > > Be aware that options specified via /chosen/stdout-path are > currently ignored by earlycon. There were some hiccups getting the > initial support upstream; when 4.4 hits mainline, I'll resubmit > my series that implements the of_serial i/o properties and > options passthrough to earlycon setup. As I said in another thread ("serial: earlycon: allow to specify uartclk in earlycon kernel-parameter"), stdout-path can pass dev->baud, but not port->uartclk. It is usually specified "clocks" phandle, but clk is not ready at the point of earlycon. It seems impossible to set up the baudrate even if the options are passed. -- Best Regards Masahiro Yamada -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 15:38 ` Masahiro Yamada 0 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-21 15:38 UTC (permalink / raw) To: linux-arm-kernel Hi Peter. 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: > On 10/21/2015 04:58 AM, Sudeep Holla wrote: >> On 21/10/15 06:09, Masahiro Yamada wrote: >>> I think there exist two ways to specify the console port and baudrate. >>> >>> >>> [1] Specify console in bootargs >>> >>> chosen { >>> bootargs = "console=ttyS0,115200"; >>> }; >>> >>> >>> [2] Specify stdout-path >>> >>> chosen { >>> stdout-path = "serial0:115200n8"; >> >> This will work for even early/boot console, so this is better than >> option [1] > > Be aware that options specified via /chosen/stdout-path are > currently ignored by earlycon. There were some hiccups getting the > initial support upstream; when 4.4 hits mainline, I'll resubmit > my series that implements the of_serial i/o properties and > options passthrough to earlycon setup. As I said in another thread ("serial: earlycon: allow to specify uartclk in earlycon kernel-parameter"), stdout-path can pass dev->baud, but not port->uartclk. It is usually specified "clocks" phandle, but clk is not ready at the point of earlycon. It seems impossible to set up the baudrate even if the options are passed. -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 22+ messages in thread
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* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 15:38 ` Masahiro Yamada @ 2015-10-21 16:26 ` Peter Hurley -1 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 16:26 UTC (permalink / raw) To: Masahiro Yamada Cc: Sudeep Holla, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA On 10/21/2015 11:38 AM, Masahiro Yamada wrote: > Hi Peter. > > 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: >> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>> I think there exist two ways to specify the console port and baudrate. >>>> >>>> >>>> [1] Specify console in bootargs >>>> >>>> chosen { >>>> bootargs = "console=ttyS0,115200"; >>>> }; >>>> >>>> >>>> [2] Specify stdout-path >>>> >>>> chosen { >>>> stdout-path = "serial0:115200n8"; >>> >>> This will work for even early/boot console, so this is better than >>> option [1] >> >> Be aware that options specified via /chosen/stdout-path are >> currently ignored by earlycon. There were some hiccups getting the >> initial support upstream; when 4.4 hits mainline, I'll resubmit >> my series that implements the of_serial i/o properties and >> options passthrough to earlycon setup. > > > As I said in another thread ("serial: earlycon: allow to specify > uartclk in earlycon kernel-parameter"), > stdout-path can pass dev->baud, but not port->uartclk. That's true but I'm not seeing in that thread where you wrote that? My replies there were specific to uartclk on the kernel command line, which isn't necessary if the bootloader has already initialized the uart. > It is usually specified "clocks" phandle, but > clk is not ready at the point of earlycon. > > It seems impossible to set up the baudrate even if the options are passed. It's difficult to understand what you're trying to do when I can't see the code you're referring to. For example, I only recently understood that you're talking about a earlycon implementation that you're working on and not the 8250 earlycon itself. If you look at other non-8250 earlycons, you'll see they all ignore the baud rate, on the assumption the bootloader already set it up. The 8250 earlycon is a little different because legacy platforms do not initialize the uart. Regards, Peter Hurley -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-21 16:26 ` Peter Hurley 0 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-21 16:26 UTC (permalink / raw) To: linux-arm-kernel On 10/21/2015 11:38 AM, Masahiro Yamada wrote: > Hi Peter. > > 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: >> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>> I think there exist two ways to specify the console port and baudrate. >>>> >>>> >>>> [1] Specify console in bootargs >>>> >>>> chosen { >>>> bootargs = "console=ttyS0,115200"; >>>> }; >>>> >>>> >>>> [2] Specify stdout-path >>>> >>>> chosen { >>>> stdout-path = "serial0:115200n8"; >>> >>> This will work for even early/boot console, so this is better than >>> option [1] >> >> Be aware that options specified via /chosen/stdout-path are >> currently ignored by earlycon. There were some hiccups getting the >> initial support upstream; when 4.4 hits mainline, I'll resubmit >> my series that implements the of_serial i/o properties and >> options passthrough to earlycon setup. > > > As I said in another thread ("serial: earlycon: allow to specify > uartclk in earlycon kernel-parameter"), > stdout-path can pass dev->baud, but not port->uartclk. That's true but I'm not seeing in that thread where you wrote that? My replies there were specific to uartclk on the kernel command line, which isn't necessary if the bootloader has already initialized the uart. > It is usually specified "clocks" phandle, but > clk is not ready at the point of earlycon. > > It seems impossible to set up the baudrate even if the options are passed. It's difficult to understand what you're trying to do when I can't see the code you're referring to. For example, I only recently understood that you're talking about a earlycon implementation that you're working on and not the 8250 earlycon itself. If you look at other non-8250 earlycons, you'll see they all ignore the baud rate, on the assumption the bootloader already set it up. The 8250 earlycon is a little different because legacy platforms do not initialize the uart. Regards, Peter Hurley ^ permalink raw reply [flat|nested] 22+ messages in thread
[parent not found: <5627BCBC.5040701-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>]
* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-21 16:26 ` Peter Hurley @ 2015-10-22 4:20 ` Masahiro Yamada -1 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-22 4:20 UTC (permalink / raw) To: Peter Hurley Cc: Sudeep Holla, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Hi Peter, 2015-10-22 1:26 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: > On 10/21/2015 11:38 AM, Masahiro Yamada wrote: >> Hi Peter. >> >> 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: >>> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>>> I think there exist two ways to specify the console port and baudrate. >>>>> >>>>> >>>>> [1] Specify console in bootargs >>>>> >>>>> chosen { >>>>> bootargs = "console=ttyS0,115200"; >>>>> }; >>>>> >>>>> >>>>> [2] Specify stdout-path >>>>> >>>>> chosen { >>>>> stdout-path = "serial0:115200n8"; >>>> >>>> This will work for even early/boot console, so this is better than >>>> option [1] >>> >>> Be aware that options specified via /chosen/stdout-path are >>> currently ignored by earlycon. There were some hiccups getting the >>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>> my series that implements the of_serial i/o properties and >>> options passthrough to earlycon setup. >> >> >> As I said in another thread ("serial: earlycon: allow to specify >> uartclk in earlycon kernel-parameter"), >> stdout-path can pass dev->baud, but not port->uartclk. > > That's true but I'm not seeing in that thread where you wrote that? Sorry, I made you confused. I was talking about the kernel parameter (console=) in the thread. > My replies there were specific to uartclk on the kernel command line, > which isn't necessary if the bootloader has already initialized the > uart. > >> It is usually specified "clocks" phandle, but >> clk is not ready at the point of earlycon. >> >> It seems impossible to set up the baudrate even if the options are passed. > > It's difficult to understand what you're trying to do when I can't > see the code you're referring to. For example, I only recently > understood that you're talking about a earlycon implementation > that you're working on and not the 8250 earlycon itself. Sorry again for making you confused. I was talking both. Now I am tackling on some ARM board porting. The board has a pure 8250 family device (compatible = "ns16550a") on it. In addition, there exist 8250-variant IPs inside the SoC. (this is similar to 8250, but slightly different. drivers/tty/serial/8250/8250_uniphier.c) What I want to do is: [1] To use drivers/tty/serial/8250/8250_early.c for the on-board ns16550a. [2] To implement my own EARLYCON_DECLARE() in drivers/tty/serial/8250/8250_uniphier.c > If you look at other non-8250 earlycons, you'll see they all ignore > the baud rate, on the assumption the bootloader already set it up. OK, I will do so for [2]. > The 8250 earlycon is a little different because legacy platforms > do not initialize the uart. Make sense. For legacy platforms, earlycon initializes the uart, assuming the hard-coded "port->uartclk = BASE_BAUD * 16" is the value. For embedded boards such as ARM, the boot-loader should initialize the UART and the earlycon should preserve it because port->uartclk varies from board to board. (For example, the ns16550a on my board expects BASE_BAUD is 1228000, but it does not match the one in include/asm-generic/serial.h ) -- Best Regards Masahiro Yamada -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-22 4:20 ` Masahiro Yamada 0 siblings, 0 replies; 22+ messages in thread From: Masahiro Yamada @ 2015-10-22 4:20 UTC (permalink / raw) To: linux-arm-kernel Hi Peter, 2015-10-22 1:26 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: > On 10/21/2015 11:38 AM, Masahiro Yamada wrote: >> Hi Peter. >> >> 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: >>> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>>> I think there exist two ways to specify the console port and baudrate. >>>>> >>>>> >>>>> [1] Specify console in bootargs >>>>> >>>>> chosen { >>>>> bootargs = "console=ttyS0,115200"; >>>>> }; >>>>> >>>>> >>>>> [2] Specify stdout-path >>>>> >>>>> chosen { >>>>> stdout-path = "serial0:115200n8"; >>>> >>>> This will work for even early/boot console, so this is better than >>>> option [1] >>> >>> Be aware that options specified via /chosen/stdout-path are >>> currently ignored by earlycon. There were some hiccups getting the >>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>> my series that implements the of_serial i/o properties and >>> options passthrough to earlycon setup. >> >> >> As I said in another thread ("serial: earlycon: allow to specify >> uartclk in earlycon kernel-parameter"), >> stdout-path can pass dev->baud, but not port->uartclk. > > That's true but I'm not seeing in that thread where you wrote that? Sorry, I made you confused. I was talking about the kernel parameter (console=) in the thread. > My replies there were specific to uartclk on the kernel command line, > which isn't necessary if the bootloader has already initialized the > uart. > >> It is usually specified "clocks" phandle, but >> clk is not ready at the point of earlycon. >> >> It seems impossible to set up the baudrate even if the options are passed. > > It's difficult to understand what you're trying to do when I can't > see the code you're referring to. For example, I only recently > understood that you're talking about a earlycon implementation > that you're working on and not the 8250 earlycon itself. Sorry again for making you confused. I was talking both. Now I am tackling on some ARM board porting. The board has a pure 8250 family device (compatible = "ns16550a") on it. In addition, there exist 8250-variant IPs inside the SoC. (this is similar to 8250, but slightly different. drivers/tty/serial/8250/8250_uniphier.c) What I want to do is: [1] To use drivers/tty/serial/8250/8250_early.c for the on-board ns16550a. [2] To implement my own EARLYCON_DECLARE() in drivers/tty/serial/8250/8250_uniphier.c > If you look at other non-8250 earlycons, you'll see they all ignore > the baud rate, on the assumption the bootloader already set it up. OK, I will do so for [2]. > The 8250 earlycon is a little different because legacy platforms > do not initialize the uart. Make sense. For legacy platforms, earlycon initializes the uart, assuming the hard-coded "port->uartclk = BASE_BAUD * 16" is the value. For embedded boards such as ARM, the boot-loader should initialize the UART and the earlycon should preserve it because port->uartclk varies from board to board. (For example, the ns16550a on my board expects BASE_BAUD is 1228000, but it does not match the one in include/asm-generic/serial.h ) -- Best Regards Masahiro Yamada ^ permalink raw reply [flat|nested] 22+ messages in thread
[parent not found: <CAK7LNASqjd_Xf53WKa=Ogesf80HQzEoKEyVtw-BMh7JF=jq+xQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>]
* Re: Which is better to specify console, "console= " or "stdout-path" ? 2015-10-22 4:20 ` Masahiro Yamada @ 2015-10-28 16:00 ` Peter Hurley -1 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-28 16:00 UTC (permalink / raw) To: Masahiro Yamada Cc: Sudeep Holla, devicetree-u79uwXL29TY76Z2rM5mHXA, linux-arm-kernel, linux-serial-u79uwXL29TY76Z2rM5mHXA Hi Masahiro, On 10/22/2015 12:20 AM, Masahiro Yamada wrote: > 2015-10-22 1:26 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: >> On 10/21/2015 11:38 AM, Masahiro Yamada wrote: >>> 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>: >>>> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>>>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>>>> I think there exist two ways to specify the console port and baudrate. >>>>>> >>>>>> >>>>>> [1] Specify console in bootargs >>>>>> >>>>>> chosen { >>>>>> bootargs = "console=ttyS0,115200"; >>>>>> }; >>>>>> >>>>>> >>>>>> [2] Specify stdout-path >>>>>> >>>>>> chosen { >>>>>> stdout-path = "serial0:115200n8"; >>>>> >>>>> This will work for even early/boot console, so this is better than >>>>> option [1] >>>> >>>> Be aware that options specified via /chosen/stdout-path are >>>> currently ignored by earlycon. There were some hiccups getting the >>>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>>> my series that implements the of_serial i/o properties and >>>> options passthrough to earlycon setup. >>> >>> >>> As I said in another thread ("serial: earlycon: allow to specify >>> uartclk in earlycon kernel-parameter"), >>> stdout-path can pass dev->baud, but not port->uartclk. >> >> That's true but I'm not seeing in that thread where you wrote that? > > Sorry, I made you confused. I was talking about the kernel parameter (console=) > in the thread. > >> My replies there were specific to uartclk on the kernel command line, >> which isn't necessary if the bootloader has already initialized the >> uart. >> >>> It is usually specified "clocks" phandle, but >>> clk is not ready at the point of earlycon. >>> >>> It seems impossible to set up the baudrate even if the options are passed. >> >> It's difficult to understand what you're trying to do when I can't >> see the code you're referring to. For example, I only recently >> understood that you're talking about a earlycon implementation >> that you're working on and not the 8250 earlycon itself. > > Sorry again for making you confused. > > I was talking both. > > Now I am tackling on some ARM board porting. > > > The board has a pure 8250 family device (compatible = "ns16550a") on it. > > In addition, there exist 8250-variant IPs inside the SoC. > (this is similar to 8250, but slightly different. > drivers/tty/serial/8250/8250_uniphier.c) > > > What I want to do is: > [1] To use drivers/tty/serial/8250/8250_early.c for the on-board ns16550a. > [2] To implement my own EARLYCON_DECLARE() in > drivers/tty/serial/8250/8250_uniphier.c > > > >> If you look at other non-8250 earlycons, you'll see they all ignore >> the baud rate, on the assumption the bootloader already set it up. > > OK, I will do so for [2]. > > >> The 8250 earlycon is a little different because legacy platforms >> do not initialize the uart. > > > Make sense. > > For legacy platforms, earlycon initializes the uart, > assuming the hard-coded "port->uartclk = BASE_BAUD * 16" > is the value. > > > For embedded boards such as ARM, the boot-loader should initialize the UART > and the earlycon should preserve it because port->uartclk varies from > board to board. > (For example, the ns16550a on my board expects BASE_BAUD is 1228000, > but it does not match the one in include/asm-generic/serial.h ) I want to clarify one point: if you have a configuration for which the earlycon uart is not initialized by the bootloader (or boot prom), then we can add a way for the ASoC init to set BASE_BAUD. This was done for the ARC arch, but I would like to use this as a last resort for the ARM arch. An example configuration I can envision that would require this solution is u-boot's so-called 'falcon mode' without devicetree (or boot prom). Regards, Peter Hurley -- 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 ^ permalink raw reply [flat|nested] 22+ messages in thread
* Which is better to specify console, "console= " or "stdout-path" ? @ 2015-10-28 16:00 ` Peter Hurley 0 siblings, 0 replies; 22+ messages in thread From: Peter Hurley @ 2015-10-28 16:00 UTC (permalink / raw) To: linux-arm-kernel Hi Masahiro, On 10/22/2015 12:20 AM, Masahiro Yamada wrote: > 2015-10-22 1:26 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: >> On 10/21/2015 11:38 AM, Masahiro Yamada wrote: >>> 2015-10-21 21:46 GMT+09:00 Peter Hurley <peter@hurleysoftware.com>: >>>> On 10/21/2015 04:58 AM, Sudeep Holla wrote: >>>>> On 21/10/15 06:09, Masahiro Yamada wrote: >>>>>> I think there exist two ways to specify the console port and baudrate. >>>>>> >>>>>> >>>>>> [1] Specify console in bootargs >>>>>> >>>>>> chosen { >>>>>> bootargs = "console=ttyS0,115200"; >>>>>> }; >>>>>> >>>>>> >>>>>> [2] Specify stdout-path >>>>>> >>>>>> chosen { >>>>>> stdout-path = "serial0:115200n8"; >>>>> >>>>> This will work for even early/boot console, so this is better than >>>>> option [1] >>>> >>>> Be aware that options specified via /chosen/stdout-path are >>>> currently ignored by earlycon. There were some hiccups getting the >>>> initial support upstream; when 4.4 hits mainline, I'll resubmit >>>> my series that implements the of_serial i/o properties and >>>> options passthrough to earlycon setup. >>> >>> >>> As I said in another thread ("serial: earlycon: allow to specify >>> uartclk in earlycon kernel-parameter"), >>> stdout-path can pass dev->baud, but not port->uartclk. >> >> That's true but I'm not seeing in that thread where you wrote that? > > Sorry, I made you confused. I was talking about the kernel parameter (console=) > in the thread. > >> My replies there were specific to uartclk on the kernel command line, >> which isn't necessary if the bootloader has already initialized the >> uart. >> >>> It is usually specified "clocks" phandle, but >>> clk is not ready at the point of earlycon. >>> >>> It seems impossible to set up the baudrate even if the options are passed. >> >> It's difficult to understand what you're trying to do when I can't >> see the code you're referring to. For example, I only recently >> understood that you're talking about a earlycon implementation >> that you're working on and not the 8250 earlycon itself. > > Sorry again for making you confused. > > I was talking both. > > Now I am tackling on some ARM board porting. > > > The board has a pure 8250 family device (compatible = "ns16550a") on it. > > In addition, there exist 8250-variant IPs inside the SoC. > (this is similar to 8250, but slightly different. > drivers/tty/serial/8250/8250_uniphier.c) > > > What I want to do is: > [1] To use drivers/tty/serial/8250/8250_early.c for the on-board ns16550a. > [2] To implement my own EARLYCON_DECLARE() in > drivers/tty/serial/8250/8250_uniphier.c > > > >> If you look at other non-8250 earlycons, you'll see they all ignore >> the baud rate, on the assumption the bootloader already set it up. > > OK, I will do so for [2]. > > >> The 8250 earlycon is a little different because legacy platforms >> do not initialize the uart. > > > Make sense. > > For legacy platforms, earlycon initializes the uart, > assuming the hard-coded "port->uartclk = BASE_BAUD * 16" > is the value. > > > For embedded boards such as ARM, the boot-loader should initialize the UART > and the earlycon should preserve it because port->uartclk varies from > board to board. > (For example, the ns16550a on my board expects BASE_BAUD is 1228000, > but it does not match the one in include/asm-generic/serial.h ) I want to clarify one point: if you have a configuration for which the earlycon uart is not initialized by the bootloader (or boot prom), then we can add a way for the ASoC init to set BASE_BAUD. This was done for the ARC arch, but I would like to use this as a last resort for the ARM arch. An example configuration I can envision that would require this solution is u-boot's so-called 'falcon mode' without devicetree (or boot prom). Regards, Peter Hurley ^ permalink raw reply [flat|nested] 22+ messages in thread
end of thread, other threads:[~2015-10-28 16:00 UTC | newest] Thread overview: 22+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-10-21 5:09 Which is better to specify console, "console= " or "stdout-path" ? Masahiro Yamada 2015-10-21 5:09 ` Masahiro Yamada [not found] ` <CAK7LNAS9uBJ1cVmGBKae3W0tk8Siu1yeXOaeN6Kz11cksMqtsg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2015-10-21 7:43 ` Arnd Bergmann 2015-10-21 7:43 ` Arnd Bergmann 2015-10-21 8:58 ` Sudeep Holla 2015-10-21 8:58 ` Sudeep Holla [not found] ` <562753A6.3070107-5wv7dgnIgG8@public.gmane.org> 2015-10-21 12:46 ` Peter Hurley 2015-10-21 12:46 ` Peter Hurley [not found] ` <56278911.9050704-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org> 2015-10-21 12:54 ` Sudeep Holla 2015-10-21 12:54 ` Sudeep Holla [not found] ` <56278AFD.8000505-5wv7dgnIgG8@public.gmane.org> 2015-10-21 13:02 ` Peter Hurley 2015-10-21 13:02 ` Peter Hurley [not found] ` <56278CF3.9010400-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org> 2015-10-21 13:06 ` Sudeep Holla 2015-10-21 13:06 ` Sudeep Holla 2015-10-21 15:38 ` Masahiro Yamada 2015-10-21 15:38 ` Masahiro Yamada [not found] ` <CAK7LNAQ_+_9K-y7bmpdGwcH2u4uqJhJhON1Ew4OvzSSa-amyvw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2015-10-21 16:26 ` Peter Hurley 2015-10-21 16:26 ` Peter Hurley [not found] ` <5627BCBC.5040701-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org> 2015-10-22 4:20 ` Masahiro Yamada 2015-10-22 4:20 ` Masahiro Yamada [not found] ` <CAK7LNASqjd_Xf53WKa=Ogesf80HQzEoKEyVtw-BMh7JF=jq+xQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org> 2015-10-28 16:00 ` Peter Hurley 2015-10-28 16:00 ` Peter Hurley
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