Date:	Tue, 05 Apr 2016 12:27:07 -0400
From:	Mark Salter <msalter@...hat.com>
To:	Aleksey Makarov <aleksey.makarov@...aro.org>,
	Russell King <linux@....linux.org.uk>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	"Zheng, Lv" <lv.zheng@...el.com>,
	Peter Hurley <peter@...leysoftware.com>,
	Graeme Gregory <graeme.gregory@...aro.org>,
	Andy Shevchenko <andy.shevchenko@...il.com>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	linux-kernel@...r.kernel.org,
	Leif Lindholm <leif.lindholm@...aro.org>,
	linux-acpi@...r.kernel.org, Yury Norov <ynorov@...iumnetworks.com>,
	Christopher Covington <cov@...eaurora.org>,
	linux-serial@...r.kernel.org, Al Stone <ahs3@...hat.com>,
	linux-arm-kernel@...ts.infradead.org, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH v7 0/5] ACPI: parse the SPCR table

Could you CC me on future postings of this series, please?

So v3 fixed a problem where platforms using 8250 didn't work.
Then in v5, that fix was lost so 8250 no longer works.

--Mark


On Thu, 2016-03-31 at 16:40 +0300, Aleksey Makarov wrote:
> 'ARM Server Base Boot Requirements' [1] mentions SPCR (Serial Port
> Console Redirection Table) [2] as a mandatory ACPI table that
> specifies the configuration of serial console.
> 
> Move "earlycon" early_param handling to earlycon.c to parse this option once
> 
> *** PATCH  "ACPICA: Headers: Add new constants for the DBG2 ACPI table"
> *** IS JUST TO ENABLE BUILDING THE PATCHSET ON linux-next
> 
> Patch "ACPICA: Headers: Add new constants for the DBG2 ACPI table" is required
> for the next patch.  It is taken from ACPICA series [3], but it has not appeared
> in linux-next yet.
> 
> Parse SPCR table, setup earlycon and add register specified console.
> 
> Enable parsing this table on ARM64.  Earlycon should be set up
> as early as possible.  ACPI boot tables are mapped in
> arch/arm64/kernel/acpi.c:acpi_boot_table_init() called from setup_arch()
> and that's where we parse spcr.  So it has to be opted-in per-arch.
> 
> Implement console_match() for pl011.
> 
> Based on the work by Leif Lindholm [4]
> Thanks to Peter Hurley for explaining how this should work.
> 
> Should be applied to next-20160331.
> 
> Tested on QEMU.  SPCR support is included in QEMU's ARM mach-virt
> since 2.4 release.
> 
> v7:
> - add Acked-by: Rob Herring for "of/serial: move earlycon early_param handling
>   to serial"
> - call DT earlycon initialization from the arch ACPI code, not from parse_spcr()
>   (Rafael J. Wysocki)
> - fix a few minor issues (Rafael J. Wysocki)
> 
> v6:
> https://lkml.kernel.org/g/1458823925-19560-1-git-send-email-aleksey.makarov@linaro.org
> - add documentation for parse_spcr() functioin (Yury Norov)
> - don't initialize err variable (Yury Norov)
> - add __initdata for the earlycon_init_is_deferred flag variable
> - rename the function exported in "of/serial: move earlycon early_param handling
>   to serial" to avoid clash with the function from arch/microblaze/kernel/prom.c
> - defer initialization of DT earlycon until DT/ACPI decision is made
>   (Rob Herring, Peter Hurley)
> - use snprintf instead of sprintf (Andy Shevchenko)
> - drop patch that adds EARLYCON_DECLARE for pl011 as EARLYCON_DECLARE is
>   equivalent to OF_EARLYCON_DECLARE for 4.6+ (Peter Hurley).  This means that
>   SPCR earlycon will not work on the kernels before 4.6
> 
> v5:
> https://lkml.kernel.org/g/1458643595-14719-1-git-send-email-aleksey.makarov@linaro.org
> - drop patch "serial: pl011: use ACPI SPCR to setup 32-bit access" because
>   it is ugly. Also because Christopher Covington came with a better solution [5]
> - remove error message when the table is not provided by ACPI (Andy Shevchenko)
> - rewrite spcr.c following the suggestions by Peter Hurley
> - add console_match() for pl011 in a separate patch
> - add EARLYCON_DECLARE for pl011 in a separate patch
> - add patch "of/serial: move earlycon early_param handling to serial" from
>   the GDB2 series
> 
> v4:
> https://lkml.kernel.org/g/1456747355-15692-1-git-send-email-aleksey.makarov@linaro.org
> - drop patch "ACPI: change __init to __ref for early_acpi_os_unmap_memory()"
>   ACPI developers work on a new API and asked not to do that.
>   Instead, use acpi_get_table_with_size()/early_acpi_os_unmap_memory() once
>   and cache the result. (Lv Zheng)
> - fix some style issues (Yury Norov)
> 
> v3:
> https://lkml.kernel.org/g/1455559532-8305-1-git-send-email-aleksey.makarov@linaro.org
> 
> Greg Kroah-Hartman did not like v2 so I have rewritten this patchset:
> 
> - drop acpi_match() member of struct console
> - drop implementations of this member for pl011 and 8250
> - drop the patch that renames some vars in printk.c as it is not needed anymore
> - drop patch that introduces system wide acpi_table_parse2().
>   Instead introduce a custom acpi_table_parse_spcr() in spcr.c
> 
> Instead of introducing a new match_acpi() member of struct console,
> this patchset introduces a new function acpi_console_check().
> This function is called when a new uart is registered at serial_core.c
> the same way OF code checks for console.  If the registered uart is the
> console specified by SPCR table, this function calls add_preferred_console()
> 
> The restrictions of this approach are:
> 
> - only serial consoles can be set up
> - only consoles specified by the memory/io address can be set up
>   (SPCR can specify devices by PCI id/PCI address)
> 
> v2:
> https://lkml.kernel.org/g/1455299022-11641-1-git-send-email-aleksey.makarov@linaro.org
> - don't use SPCR if user specified console in command line
> - fix initialization order of newcon->index = 0
> - rename some variables at printk.c (Joe Perches, Peter Hurley)
> - enable ACPI_SPCR_TABLE in a separate patch (Andy Shevchenko)
> - remove the retry loop for console registering (Peter Hurley).
>   Instead, obtain SPCR with acpi_get_table().  That works after
>   call to acpi_early_init() i. e. in any *_initcall()
> - describe design decision behind introducing acpi_match() (Peter Hurley)
> - fix compilation for x86 + ACPI (Graeme Gregory)
> - introduce DBG2 constants in a separate patch (Andy Shevchenko)
> - fix a typo in DBG2 constants (Andy Shevchenko)
> - add ACPI_DBG2_ARM_SBSA_32BIT constant (Christopher Covington)
> - add support for ACPI_DBG2_ARM_SBSA_* consoles (Christopher Covington)
> - add documentation for functions
> - add a patch that uses SPCR to find if SBSA serial driver should use 32-bit
>   accessor functions (Christopher Covington)
> - change __init to __ref for early_acpi_os_unmap_memory() in a separate patch
> - introduce acpi_table_parse2() in a separate patch
> - fix fetching the SPCR table early (Mark Salter)
> - add a patch from Mark Salter that introduces support for matching 8250-based
>   consoles
> 
> v1:
> https://lkml.kernel.org/g/1453722324-22407-1-git-send-email-aleksey.makarov@linaro.org
> 
> [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html
> [2] https://msdn.microsoft.com/en-us/library/windows/hardware/dn639132(v=vs.85).aspx
> [3] https://lkml.kernel.org/g/cover.1458714002.git.lv.zheng@intel.com
> [4] https://lkml.kernel.org/g/1441716217-23786-1-git-send-email-leif.lindholm@linaro.org
> [5] https://lkml.kernel.org/g/1457415800-8799-1-git-send-email-cov@codeaurora.org
> 
> Aleksey Makarov (4):
>   ACPICA: Headers: Add new constants for the DBG2 ACPI table
>   ACPI: parse SPCR and enable matching console
>   ARM64: ACPI: enable ACPI_SPCR_TABLE
>   serial: pl011: add console matching function
> 
> Leif Lindholm (1):
>   of/serial: move earlycon early_param handling to serial
> 
>  arch/arm64/Kconfig              |   1 +
>  arch/arm64/kernel/acpi.c        |  11 +++-
>  drivers/acpi/Kconfig            |   3 ++
>  drivers/acpi/Makefile           |   1 +
>  drivers/acpi/spcr.c             | 111 ++++++++++++++++++++++++++++++++++++++++
>  drivers/of/fdt.c                |  11 +---
>  drivers/tty/serial/amba-pl011.c |  56 ++++++++++++++++++++
>  drivers/tty/serial/earlycon.c   |  19 ++++++-
>  include/acpi/actbl2.h           |   7 ++-
>  include/linux/acpi.h            |   6 +++
>  include/linux/of_fdt.h          |   2 +
>  include/linux/serial_core.h     |   6 +++
>  12 files changed, 220 insertions(+), 14 deletions(-)
>  create mode 100644 drivers/acpi/spcr.c
> 

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