Message-ID: <20171213100858.GA27635@arm.com>
Date:   Wed, 13 Dec 2017 10:08:59 +0000
From:   Will Deacon <will.deacon@....com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Prarit Bhargava <prarit@...hat.com>, linux-acpi@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org,
        linux-serial@...r.kernel.org, Bhupesh Sharma <bhsharma@...hat.com>,
        Lv Zheng <lv.zheng@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>,
        Timur Tabi <timur@...eaurora.org>, sudeep.holla@....com,
        hanjun.guo@...aro.org, lorenzo.pieralisi@....com
Subject: Re: [PATCH v2 1/2] acpi, spcr: Make SPCR avialable to other
 architectures

[adding Lorenzo, Sudeep and Hanjun -- see Rafael's comment below]

On Wed, Dec 13, 2017 at 01:22:59AM +0100, Rafael J. Wysocki wrote:
> On Monday, December 11, 2017 4:50:58 PM CET Prarit Bhargava wrote:
> > Other architectures can use SPCR to setup an early console or console
> > but the current code is ARM64 specific.
> > 
> > Change the name of parse_spcr() to acpi_parse_spcr().  Add a weak
> > function acpi_arch_setup_console() that can be used for arch-specific
> > setup.  Move flags into ACPI code.  Update the Documention on the use of
> > the SPCR.
> > 
> > [v2]: Don't return an error in the baud_rate check of acpi_parse_spcr().
> > Keep ACPI_SPCR_TABLE selected for ARM64.  Fix 8-bit port access width
> > mmio value.  Move baud rate check earlier.
> > 
> > Signed-off-by: Prarit Bhargava <prarit@...hat.com>
> 
> This mostly affects ARM64, so ACKs from that side are requisite for it.
> 
> > Cc: linux-doc@...r.kernel.org
> > Cc: linux-kernel@...r.kernel.org
> > Cc: linux-arm-kernel@...ts.infradead.org
> > Cc: linux-pm@...r.kernel.org
> > Cc: linux-acpi@...r.kernel.org
> > Cc: linux-serial@...r.kernel.org
> > Cc: Bhupesh Sharma <bhsharma@...hat.com>
> > Cc: Lv Zheng <lv.zheng@...el.com>
> > Cc: Thomas Gleixner <tglx@...utronix.de>
> > Cc: Ingo Molnar <mingo@...hat.com>
> > Cc: "H. Peter Anvin" <hpa@...or.com>
> > Cc: x86@...nel.org
> > Cc: Jonathan Corbet <corbet@....net>
> > Cc: Catalin Marinas <catalin.marinas@....com>
> > Cc: Will Deacon <will.deacon@....com>
> > Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> > Cc: Timur Tabi <timur@...eaurora.org>
> > ---
> >  Documentation/admin-guide/kernel-parameters.txt |   6 +-
> >  arch/arm64/kernel/acpi.c                        | 128 ++++++++++++++++-
> >  drivers/acpi/Kconfig                            |   7 +-
> >  drivers/acpi/spcr.c                             | 175 ++++++------------------
> >  drivers/tty/serial/earlycon.c                   |  15 +-
> >  include/linux/acpi.h                            |  11 +-
> >  include/linux/serial_core.h                     |   2 -
> >  7 files changed, 184 insertions(+), 160 deletions(-)
> > 
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> > index 6571fbfdb2a1..0d173289c67e 100644
> > --- a/Documentation/admin-guide/kernel-parameters.txt
> > +++ b/Documentation/admin-guide/kernel-parameters.txt
> > @@ -914,9 +914,9 @@
> >  
> >  	earlycon=	[KNL] Output early console device and options.
> >  
> > -			When used with no options, the early console is
> > -			determined by the stdout-path property in device
> > -			tree's chosen node.
> > +			[ARM64] The early console is determined by the
> > +			stdout-path property in device tree's chosen node,
> > +			or determined by the ACPI SPCR table.
> >  
> >  		cdns,<addr>[,options]
> >  			Start an early, polled-mode console on a Cadence
> > diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> > index b3162715ed78..b3e33bbdf3b7 100644
> > --- a/arch/arm64/kernel/acpi.c
> > +++ b/arch/arm64/kernel/acpi.c
> > @@ -25,7 +25,6 @@
> >  #include <linux/memblock.h>
> >  #include <linux/of_fdt.h>
> >  #include <linux/smp.h>
> > -#include <linux/serial_core.h>
> >  
> >  #include <asm/cputype.h>
> >  #include <asm/cpu_ops.h>
> > @@ -177,6 +176,128 @@ static int __init acpi_fadt_sanity_check(void)
> >  	return ret;
> >  }
> >  
> > +/*
> > + * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
> > + * occasionally getting stuck as 1. To avoid the potential for a hang, check
> > + * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
> > + * implementations, so only do so if an affected platform is detected in
> > + * acpi_parse_spcr().
> > + */
> > +bool qdf2400_e44_present;
> > +EXPORT_SYMBOL(qdf2400_e44_present);
> > +
> > +/*
> > + * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
> > + * Detect them by examining the OEM fields in the SPCR header, similar to PCI
> > + * quirk detection in pci_mcfg.c.
> > + */
> > +static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
> > +{
> > +	if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
> > +		return false;
> > +
> > +	if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
> > +		return true;
> > +
> > +	if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
> > +			h->oem_revision == 1)
> > +		return true;
> > +
> > +	return false;
> > +}
> > +
> > +/*
> > + * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
> > + * register aligned to 32-bit. In addition, the BIOS also encoded the
> > + * access width to be 8 bits. This function detects this errata condition.
> > + */
> > +static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> > +{
> > +	bool xgene_8250 = false;
> > +
> > +	if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
> > +		return false;
> > +
> > +	if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
> > +	    memcmp(tb->header.oem_id, "HPE   ", ACPI_OEM_ID_SIZE))
> > +		return false;
> > +
> > +	if (!memcmp(tb->header.oem_table_id, "XGENESPC",
> > +	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
> > +		xgene_8250 = true;
> > +
> > +	if (!memcmp(tb->header.oem_table_id, "ProLiant",
> > +	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
> > +		xgene_8250 = true;
> > +
> > +	return xgene_8250;
> > +}
> > +
> > +int acpi_arch_setup_console(struct acpi_table_spcr *table,
> > +			    char *opts, char *uart, char *iotype,
> > +			    int baud_rate, bool earlycon)
> > +{
> > +	if (table->header.revision < 2) {
> > +		pr_err("wrong table version\n");
> > +		return -ENOENT;
> > +	}
> > +
> > +	switch (table->interface_type) {
> > +	case ACPI_DBG2_ARM_SBSA_32BIT:
> > +		snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio32");
> > +		/* fall through */
> > +	case ACPI_DBG2_ARM_PL011:
> > +	case ACPI_DBG2_ARM_SBSA_GENERIC:
> > +	case ACPI_DBG2_BCM2835:
> > +		snprintf(uart, ACPI_SPCR_BUF_SIZE, "pl011");
> > +		break;
> > +	default:
> > +		if (strlen(uart) == 0)
> > +			return -ENOENT;
> > +	}
> > +
> > +	/*
> > +	 * If the E44 erratum is required, then we need to tell the pl011
> > +	 * driver to implement the work-around.
> > +	 *
> > +	 * The global variable is used by the probe function when it
> > +	 * creates the UARTs, whether or not they're used as a console.
> > +	 *
> > +	 * If the user specifies "traditional" earlycon, the qdf2400_e44
> > +	 * console name matches the EARLYCON_DECLARE() statement, and
> > +	 * SPCR is not used.  Parameter "earlycon" is false.
> > +	 *
> > +	 * If the user specifies "SPCR" earlycon, then we need to update
> > +	 * the console name so that it also says "qdf2400_e44".  Parameter
> > +	 * "earlycon" is true.
> > +	 *
> > +	 * For consistency, if we change the console name, then we do it
> > +	 * for everyone, not just earlycon.
> > +	 */
> > +	if (qdf2400_erratum_44_present(&table->header)) {
> > +		qdf2400_e44_present = true;
> > +		if (earlycon)
> > +			snprintf(uart, ACPI_SPCR_BUF_SIZE, "qdf2400_e44");
> > +	}
> > +
> > +	if (xgene_8250_erratum_present(table)) {
> > +		snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio32");
> > +
> > +		/* for xgene v1 and v2 we don't know the clock rate of the
> > +		 * UART so don't attempt to change to the baud rate state
> > +		 * in the table because driver cannot calculate the dividers
> > +		 */
> > +		snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx", uart,
> > +			 iotype, table->serial_port.address);
> > +	} else {
> > +		snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx,%d", uart,
> > +			 iotype, table->serial_port.address, baud_rate);
> > +	}
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL(acpi_arch_setup_console);
> > +
> >  /*
> >   * acpi_boot_table_init() called from setup_arch(), always.
> >   *	1. find RSDP and get its address, and then find XSDT
> > @@ -230,10 +351,11 @@ void __init acpi_boot_table_init(void)
> >  
> >  done:
> >  	if (acpi_disabled) {
> > -		if (earlycon_init_is_deferred)
> > +		if (console_acpi_spcr_enable)
> >  			early_init_dt_scan_chosen_stdout();
> >  	} else {
> > -		parse_spcr(earlycon_init_is_deferred);
> > +		/* Always enable the ACPI SPCR console */
> > +		acpi_parse_spcr(console_acpi_spcr_enable);
> >  		if (IS_ENABLED(CONFIG_ACPI_BGRT))
> >  			acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);
> >  	}
> > diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> > index 46505396869e..9ae98eeada76 100644
> > --- a/drivers/acpi/Kconfig
> > +++ b/drivers/acpi/Kconfig
> > @@ -79,7 +79,12 @@ config ACPI_DEBUGGER_USER
> >  endif
> >  
> >  config ACPI_SPCR_TABLE
> > -	bool
> > +	bool "ACPI Serial Port Console Redirection Support"
> > +	default y if ARM64
> > +	help
> > +	  Enable support for Serial Port Console Redirection (SPCR) Table.
> > +	  This table provides information about the configuration of the
> > +	  earlycon console.
> >  
> >  config ACPI_LPIT
> >  	bool
> > diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> > index 324b35bfe781..f4bb8110e404 100644
> > --- a/drivers/acpi/spcr.c
> > +++ b/drivers/acpi/spcr.c
> > @@ -16,65 +16,18 @@
> >  #include <linux/kernel.h>
> >  #include <linux/serial_core.h>
> >  
> > -/*
> > - * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
> > - * occasionally getting stuck as 1. To avoid the potential for a hang, check
> > - * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
> > - * implementations, so only do so if an affected platform is detected in
> > - * parse_spcr().
> > - */
> > -bool qdf2400_e44_present;
> > -EXPORT_SYMBOL(qdf2400_e44_present);
> > -
> > -/*
> > - * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
> > - * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
> > - * quirk detection in pci_mcfg.c.
> > - */
> > -static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
> > -{
> > -	if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
> > -		return false;
> > -
> > -	if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
> > -		return true;
> > -
> > -	if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
> > -			h->oem_revision == 1)
> > -		return true;
> > -
> > -	return false;
> > -}
> > -
> > -/*
> > - * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
> > - * register aligned to 32-bit. In addition, the BIOS also encoded the
> > - * access width to be 8 bits. This function detects this errata condition.
> > - */
> > -static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> > +int __weak acpi_arch_setup_console(struct acpi_table_spcr *table,
> > +				   char *opts, char *uart, char *iotype,
> > +				   int baud_rate, bool earlycon)
> >  {
> > -	bool xgene_8250 = false;
> > -
> > -	if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
> > -		return false;
> > -
> > -	if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
> > -	    memcmp(tb->header.oem_id, "HPE   ", ACPI_OEM_ID_SIZE))
> > -		return false;
> > -
> > -	if (!memcmp(tb->header.oem_table_id, "XGENESPC",
> > -	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
> > -		xgene_8250 = true;
> > -
> > -	if (!memcmp(tb->header.oem_table_id, "ProLiant",
> > -	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
> > -		xgene_8250 = true;
> > -
> > -	return xgene_8250;
> > +	snprintf(opts, ACPI_SPCR_OPTS_SIZE, "%s,%s,0x%llx,%d", uart, iotype,
> > +		 table->serial_port.address, baud_rate);
> > +	return 0;
> >  }
> >  
> > +bool console_acpi_spcr_enable __initdata;
> >  /**
> > - * parse_spcr() - parse ACPI SPCR table and add preferred console
> > + * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console
> >   *
> >   * @earlycon: set up earlycon for the console specified by the table
> >   *
> > @@ -86,13 +39,13 @@ static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
> >   * from arch initialization code as soon as the DT/ACPI decision is made.
> >   *
> >   */
> > -int __init parse_spcr(bool earlycon)
> > +int __init acpi_parse_spcr(bool earlycon)
> >  {
> > -	static char opts[64];
> > +	static char opts[ACPI_SPCR_OPTS_SIZE];
> > +	static char uart[ACPI_SPCR_BUF_SIZE];
> > +	static char iotype[ACPI_SPCR_BUF_SIZE];
> >  	struct acpi_table_spcr *table;
> >  	acpi_status status;
> > -	char *uart;
> > -	char *iotype;
> >  	int baud_rate;
> >  	int err;
> >  
> > @@ -105,48 +58,6 @@ int __init parse_spcr(bool earlycon)
> >  	if (ACPI_FAILURE(status))
> >  		return -ENOENT;
> >  
> > -	if (table->header.revision < 2) {
> > -		err = -ENOENT;
> > -		pr_err("wrong table version\n");
> > -		goto done;
> > -	}
> > -
> > -	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> > -		switch (ACPI_ACCESS_BIT_WIDTH((
> > -			table->serial_port.access_width))) {
> > -		default:
> > -			pr_err("Unexpected SPCR Access Width.  Defaulting to byte size\n");
> > -		case 8:
> > -			iotype = "mmio";
> > -			break;
> > -		case 16:
> > -			iotype = "mmio16";
> > -			break;
> > -		case 32:
> > -			iotype = "mmio32";
> > -			break;
> > -		}
> > -	} else
> > -		iotype = "io";
> > -
> > -	switch (table->interface_type) {
> > -	case ACPI_DBG2_ARM_SBSA_32BIT:
> > -		iotype = "mmio32";
> > -		/* fall through */
> > -	case ACPI_DBG2_ARM_PL011:
> > -	case ACPI_DBG2_ARM_SBSA_GENERIC:
> > -	case ACPI_DBG2_BCM2835:
> > -		uart = "pl011";
> > -		break;
> > -	case ACPI_DBG2_16550_COMPATIBLE:
> > -	case ACPI_DBG2_16550_SUBSET:
> > -		uart = "uart";
> > -		break;
> > -	default:
> > -		err = -ENOENT;
> > -		goto done;
> > -	}
> > -
> >  	switch (table->baud_rate) {
> >  	case 3:
> >  		baud_rate = 9600;
> > @@ -165,43 +76,36 @@ int __init parse_spcr(bool earlycon)
> >  		goto done;
> >  	}
> >  
> > -	/*
> > -	 * If the E44 erratum is required, then we need to tell the pl011
> > -	 * driver to implement the work-around.
> > -	 *
> > -	 * The global variable is used by the probe function when it
> > -	 * creates the UARTs, whether or not they're used as a console.
> > -	 *
> > -	 * If the user specifies "traditional" earlycon, the qdf2400_e44
> > -	 * console name matches the EARLYCON_DECLARE() statement, and
> > -	 * SPCR is not used.  Parameter "earlycon" is false.
> > -	 *
> > -	 * If the user specifies "SPCR" earlycon, then we need to update
> > -	 * the console name so that it also says "qdf2400_e44".  Parameter
> > -	 * "earlycon" is true.
> > -	 *
> > -	 * For consistency, if we change the console name, then we do it
> > -	 * for everyone, not just earlycon.
> > -	 */
> > -	if (qdf2400_erratum_44_present(&table->header)) {
> > -		qdf2400_e44_present = true;
> > -		if (earlycon)
> > -			uart = "qdf2400_e44";
> > +	switch (table->interface_type) {
> > +	case ACPI_DBG2_16550_COMPATIBLE:
> > +	case ACPI_DBG2_16550_SUBSET:
> > +		snprintf(uart, ACPI_SPCR_BUF_SIZE, "uart");
> > +		break;
> > +	default:
> > +		break;
> >  	}
> >  
> > -	if (xgene_8250_erratum_present(table)) {
> > -		iotype = "mmio32";
> > +	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
> > +		u8 width = ACPI_ACCESS_BIT_WIDTH((
> > +					table->serial_port.access_width));
> > +		switch (width) {
> > +		default:
> > +			pr_err("Unexpected SPCR Access Width.  Defaulting to byte size\n");
> > +		case 8:
> > +			snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio");
> > +			break;
> > +		case 16:
> > +		case 32:
> > +			snprintf(iotype, ACPI_SPCR_BUF_SIZE, "mmio%d", width);
> > +			break;
> > +		}
> > +	} else
> > +		snprintf(iotype, ACPI_SPCR_BUF_SIZE, "io");
> >  
> > -		/* for xgene v1 and v2 we don't know the clock rate of the
> > -		 * UART so don't attempt to change to the baud rate state
> > -		 * in the table because driver cannot calculate the dividers
> > -		 */
> > -		snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
> > -			 table->serial_port.address);
> > -	} else {
> > -		snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
> > -			 table->serial_port.address, baud_rate);
> > -	}
> > +	err = acpi_arch_setup_console(table, opts, uart, iotype, baud_rate,
> > +				      earlycon);
> > +	if (err)
> > +		goto done;
> >  
> >  	pr_info("console: %s\n", opts);
> >  
> > @@ -209,7 +113,6 @@ int __init parse_spcr(bool earlycon)
> >  		setup_earlycon(opts);
> >  
> >  	err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
> > -
> >  done:
> >  	acpi_put_table((struct acpi_table_header *)table);
> >  	return err;
> > diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
> > index 4c8b80f1c688..b22afb62c7a3 100644
> > --- a/drivers/tty/serial/earlycon.c
> > +++ b/drivers/tty/serial/earlycon.c
> > @@ -196,26 +196,15 @@ int __init setup_earlycon(char *buf)
> >  	return -ENOENT;
> >  }
> >  
> > -/*
> > - * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in
> > - * command line does not start DT earlycon immediately, instead it defers
> > - * starting it until DT/ACPI decision is made.  At that time if ACPI is enabled
> > - * call parse_spcr(), else call early_init_dt_scan_chosen_stdout()
> > - */
> > -bool earlycon_init_is_deferred __initdata;
> > -
> >  /* early_param wrapper for setup_earlycon() */
> >  static int __init param_setup_earlycon(char *buf)
> >  {
> >  	int err;
> >  
> > -	/*
> > -	 * Just 'earlycon' is a valid param for devicetree earlycons;
> > -	 * don't generate a warning from parse_early_params() in that case
> > -	 */
> > +	/* Just 'earlycon' is a valid param for devicetree and ACPI SPCR. */
> >  	if (!buf || !buf[0]) {
> >  		if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
> > -			earlycon_init_is_deferred = true;
> > +			console_acpi_spcr_enable = true;
> >  			return 0;
> >  		} else if (!buf) {
> >  			return early_init_dt_scan_chosen_stdout();
> > diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> > index dc1ebfeeb5ec..875d7327d91c 100644
> > --- a/include/linux/acpi.h
> > +++ b/include/linux/acpi.h
> > @@ -1241,10 +1241,17 @@ static inline bool acpi_has_watchdog(void) { return false; }
> >  #endif
> >  
> >  #ifdef CONFIG_ACPI_SPCR_TABLE
> > +#define ACPI_SPCR_OPTS_SIZE 64
> > +#define ACPI_SPCR_BUF_SIZE 32
> >  extern bool qdf2400_e44_present;
> > -int parse_spcr(bool earlycon);
> > +extern bool console_acpi_spcr_enable __initdata;
> > +extern int acpi_arch_setup_console(struct acpi_table_spcr *table,
> > +				   char *opts, char *uart, char *iotype,
> > +				   int baud_rate, bool earlycon);
> > +int acpi_parse_spcr(bool earlycon);
> >  #else
> > -static inline int parse_spcr(bool earlycon) { return 0; }
> > +static const bool console_acpi_spcr_enable;
> > +static inline int acpi_parse_spcr(bool earlycon) { return 0; }
> >  #endif
> >  
> >  #if IS_ENABLED(CONFIG_ACPI_GENERIC_GSI)
> > diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> > index 37b044e78333..abfffb4b1c37 100644
> > --- a/include/linux/serial_core.h
> > +++ b/include/linux/serial_core.h
> > @@ -376,10 +376,8 @@ extern int of_setup_earlycon(const struct earlycon_id *match,
> >  			     const char *options);
> >  
> >  #ifdef CONFIG_SERIAL_EARLYCON
> > -extern bool earlycon_init_is_deferred __initdata;
> >  int setup_earlycon(char *buf);
> >  #else
> > -static const bool earlycon_init_is_deferred;
> >  static inline int setup_earlycon(char *buf) { return 0; }
> >  #endif
> >  
> > 
> 
> 

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