mail archive of the barebox mailing list
 help / color / mirror / Atom feed
From: Roland Hieber <rhi@pengutronix.de>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: barebox@lists.infradead.org, sam@ravnborg.org
Subject: Re: [PATCH v3 13/15] ARM: at91: microchip-ksz9477-evb: implement first stage
Date: Mon, 1 Apr 2019 14:37:58 +0200	[thread overview]
Message-ID: <20190401123758.ubx75kuc6shvuht3@pengutronix.de> (raw)
In-Reply-To: <20190401101822.7392-14-a.fatoum@pengutronix.de>

On Mon, Apr 01, 2019 at 12:18:21PM +0200, Ahmad Fatoum wrote:
> This imports the low level init code from at91bootstrap
> https://github.com/linux4sam/at91bootstrap/blob/v3.8.12/board/sama5d3_xplained/sama5d3_xplained.c
> 
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  .../boards/microchip-ksz9477-evb/lowlevel.c   | 208 +++++++++++++++++-
>  arch/arm/mach-at91/Kconfig                    |   2 +
>  arch/arm/mach-at91/include/mach/at91_pmc.h    |   8 +
>  arch/arm/mach-at91/include/mach/sama5d3.h     |   1 +
>  images/Makefile.at91                          |   5 +
>  5 files changed, 220 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/boards/microchip-ksz9477-evb/lowlevel.c b/arch/arm/boards/microchip-ksz9477-evb/lowlevel.c
> index 4293f8aaa57d..cf44021bdfb7 100644
> --- a/arch/arm/boards/microchip-ksz9477-evb/lowlevel.c
> +++ b/arch/arm/boards/microchip-ksz9477-evb/lowlevel.c
> @@ -1,7 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0-only AND BSD-1-Clause
>  /*
> + * Copyright (c) 2014, Atmel Corporation
>   * Copyright (C) 2018 Ahmad Fatoum, Pengutronix
>   *
> - * Under GPLv2
> + *
> + * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
> + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
> + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
> + * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
> + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
> + * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
> + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
> + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
> + * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>   */

Here you included the original disclaimer? For what reason? :)

 - Roland

>  
>  #include <common.h>
> @@ -10,18 +22,206 @@
>  #include <asm/barebox-arm-head.h>
>  #include <asm/barebox-arm.h>
>  
> -#include <mach/hardware.h>
> +#include <debug_ll.h>
> +#include <linux/kconfig.h>
> +#include <mach/at91_dbgu.h>
> +#include <mach/at91_ddrsdrc.h>
> +#include <mach/at91_pmc_ll.h>
> +#include <mach/at91_pio.h>
> +#include <mach/at91_wdt.h>
> +#include <mach/ddramc.h>
> +#include <mach/early_udelay.h>
> +#include <mach/gpio.h>
> +#include <mach/iomux.h>
> +
> +/* PCK = 528MHz, MCK = 132MHz */
> +#define MASTER_CLOCK	132000000
> +
> +#define PMC_BASE IOMEM(SAMA5D3_BASE_PMC)
> +#define sama5d3_pmc_enable_periph_clock(clk) \
> +	at91_pmc_enable_periph_clock(PMC_BASE, clk)
> +
> +#define BAUDRATE(mck, baud) \
> +	((((((mck) * 10) / ((baud) * 16)) % 10) >= 5) ? \
> +	(mck / (baud * 16) + 1) : ((mck) / (baud * 16)))
> +
> +
> +static void configure_periph_a_piob_pin(unsigned int pin)
> +{
> +	void __iomem *pio = IOMEM(SAMA5D3_BASE_PIOB);
> +	u32 mask = pin_to_mask(pin);
> +
> +	at91_mux_disable_interrupt(pio, mask);
> +	at91_mux_set_pullup(pio, mask, 0);
> +	at91_mux_pio3_set_pulldown(pio, mask, 0);
> +
> +	at91_mux_pio3_set_A_periph(pio, mask);
> +
> +	at91_mux_gpio_disable(pio, mask);
> +}
> +
> +static noinline void dbgu_init(void)
> +{
> +	sama5d3_pmc_enable_periph_clock(SAMA5D3_ID_PIOB);
> +
> +	configure_periph_a_piob_pin(AT91_PIN_PB30);
> +	configure_periph_a_piob_pin(AT91_PIN_PB31);
> +
> +	sama5d3_pmc_enable_periph_clock(SAMA5D3_ID_DBGU);
> +	at91_dbgu_setup_ll(AT91_BASE_DBGU1, BAUDRATE(MASTER_CLOCK, 115200));
> +
> +	putc_ll('>');
> +}
> +
> +static void ddramc_reg_config(struct at91_ddramc_register *ddramc_config)
> +{
> +	ddramc_config->mdr = (AT91C_DDRC2_DBW_32_BITS
> +				| AT91C_DDRC2_MD_DDR2_SDRAM);
> +
> +	ddramc_config->cr = (AT91C_DDRC2_NC_DDR10_SDR9
> +				| AT91C_DDRC2_NR_13
> +				| AT91C_DDRC2_CAS_3
> +				| AT91C_DDRC2_DISABLE_RESET_DLL
> +				| AT91C_DDRC2_ENABLE_DLL
> +				| AT91C_DDRC2_ENRDM_ENABLE
> +				| AT91C_DDRC2_NB_BANKS_8
> +				| AT91C_DDRC2_NDQS_DISABLED
> +				| AT91C_DDRC2_DECOD_INTERLEAVED
> +				| AT91C_DDRC2_UNAL_SUPPORTED);
> +
> +	/*
> +	 * The DDR2-SDRAM device requires a refresh every 15.625 us or 7.81 us.
> +	 * With a 133 MHz frequency, the refresh timer count register must to be
> +	 * set with (15.625 x 133 MHz) ~ 2084 i.e. 0x824
> +	 * or (7.81 x 133 MHz) ~ 1039 i.e. 0x40F.
> +	 */
> +	ddramc_config->rtr = 0x40F;     /* Refresh timer: 7.812us */
> +
> +	/* One clock cycle @ 133 MHz = 7.5 ns */
> +	ddramc_config->t0pr = (AT91C_DDRC2_TRAS_(6)	/* 6 * 7.5 = 45 ns */
> +			| AT91C_DDRC2_TRCD_(2)		/* 2 * 7.5 = 22.5 ns */
> +			| AT91C_DDRC2_TWR_(2)		/* 2 * 7.5 = 15   ns */
> +			| AT91C_DDRC2_TRC_(8)		/* 8 * 7.5 = 75   ns */
> +			| AT91C_DDRC2_TRP_(2)		/* 2 * 7.5 = 15   ns */
> +			| AT91C_DDRC2_TRRD_(2)		/* 2 * 7.5 = 15   ns */
> +			| AT91C_DDRC2_TWTR_(2)		/* 2 clock cycles min */
> +			| AT91C_DDRC2_TMRD_(2));	/* 2 clock cycles */
> +
> +	ddramc_config->t1pr = (AT91C_DDRC2_TXP_(2)	/* 2 clock cycles */
> +			| AT91C_DDRC2_TXSRD_(200)	/* 200 clock cycles */
> +			| AT91C_DDRC2_TXSNR_(19)	/* 19 * 7.5 = 142.5 ns */
> +			| AT91C_DDRC2_TRFC_(17));	/* 17 * 7.5 = 127.5 ns */
> +
> +	ddramc_config->t2pr = (AT91C_DDRC2_TFAW_(6)	/* 6 * 7.5 = 45 ns */
> +			| AT91C_DDRC2_TRTP_(2)		/* 2 clock cycles min */
> +			| AT91C_DDRC2_TRPA_(2)		/* 2 * 7.5 = 15 ns */
> +			| AT91C_DDRC2_TXARDS_(8)	/* = TXARD */
> +			| AT91C_DDRC2_TXARD_(8));	/* MR12 = 1 */
> +}
> +
> +static void sama5d3_ddramc_init(void)
> +{
> +	struct at91_ddramc_register ddramc_reg;
> +	u32 reg;
> +
> +	ddramc_reg_config(&ddramc_reg);
> +
> +	/* enable ddr2 clock */
> +	sama5d3_pmc_enable_periph_clock(SAMA5D3_ID_MPDDRC);
> +	at91_pmc_enable_system_clock(PMC_BASE, AT91CAP9_PMC_DDR);
> +
> +
> +	/* Init the special register for sama5d3x */
> +	/* MPDDRC DLL Slave Offset Register: DDR2 configuration */
> +	reg = AT91C_MPDDRC_S0OFF_1
> +		| AT91C_MPDDRC_S2OFF_1
> +		| AT91C_MPDDRC_S3OFF_1;
> +	writel(reg, SAMA5D3_BASE_MPDDRC + AT91C_MPDDRC_DLL_SOR);
>  
> +	/* MPDDRC DLL Master Offset Register */
> +	/* write master + clk90 offset */
> +	reg = AT91C_MPDDRC_MOFF_7
> +		| AT91C_MPDDRC_CLK90OFF_31
> +		| AT91C_MPDDRC_SELOFF_ENABLED | AT91C_MPDDRC_KEY;
> +	writel(reg, SAMA5D3_BASE_MPDDRC + AT91C_MPDDRC_DLL_MOR);
> +
> +	/* MPDDRC I/O Calibration Register */
> +	/* DDR2 RZQ = 50 Ohm */
> +	/* TZQIO = 4 */
> +	reg = AT91C_MPDDRC_RDIV_DDR2_RZQ_50
> +		| AT91C_MPDDRC_TZQIO_4;
> +	writel(reg, SAMA5D3_BASE_MPDDRC + AT91C_MPDDRC_IO_CALIBR);
> +
> +	/* DDRAM2 Controller initialize */
> +	at91_ddram_initialize(SAMA5D3_BASE_MPDDRC, SAMA5_DDRCS, &ddramc_reg);
> +}
> +
> +extern char __dtb_z_at91_microchip_ksz9477_evb_boot_bin_start[];
>  extern char __dtb_z_at91_microchip_ksz9477_evb_start[];
>  
> -ENTRY_FUNCTION(start_sama5d3_xplained_ung8071, r0, r1, r2)
> +static noinline void board_init(void)
>  {
> -	void *fdt;
> +	void *fdt = NULL;
> +
> +	at91_wdt_disable(IOMEM(SAMA5D3_BASE_WDT));
> +	at91_pmc_init(PMC_BASE, AT91_PMC_LL_SAMA5D3);
> +
> +	/* At this stage the main oscillator
> +	 * is supposed to be enabled PCK = MCK = MOSC
> +	 */
> +
> +	/* Configure PLLA = MOSC * (PLL_MULA + 1) / PLL_DIVA */
> +	at91_pmc_cfg_plla(PMC_BASE, AT91_PMC3_MUL_(43) | AT91_PMC_OUT_0
> +			  | AT91_PMC_PLLCOUNT
> +			  | AT91_PMC_DIV_BYPASS,
> +			  AT91_PMC_LL_SAMA5D3);
> +
> +	/* Initialize PLLA charge pump */
> +	at91_pmc_init_pll(PMC_BASE, AT91_PMC_IPLLA_3);
> +
> +	/* Switch PCK/MCK on Main clock output */
> +	at91_pmc_cfg_mck(PMC_BASE, AT91SAM9_PMC_MDIV_4 | AT91_PMC_CSS_MAIN,
> +			 AT91_PMC_LL_SAMA5D3);
> +
> +	/* Switch PCK/MCK on PLLA output */
> +	at91_pmc_cfg_mck(PMC_BASE, AT91SAM9_PMC_MDIV_4 | AT91_PMC_CSS_PLLA,
> +			 AT91_PMC_LL_SAMA5D3);
> +
> +	if (IS_ENABLED(CONFIG_DEBUG_LL))
> +		dbgu_init();
> +
> +	early_udelay_init(PMC_BASE, IOMEM(SAMA5D3_BASE_PIT),
> +			  SAMA5D3_ID_PIT, MASTER_CLOCK, AT91_PMC_LL_SAMA5D3);
> +
> +	sama5d3_ddramc_init();
>  
> +	fdt = __dtb_z_at91_microchip_ksz9477_evb_boot_bin_start + get_runtime_offset();
> +
> +	barebox_arm_entry(SAMA5_DDRCS, SZ_256M, fdt);
> +}
> +
> +ENTRY_FUNCTION(start_sama5d3_xplained_ung8071_boot_bin, r0, r1, r2)
> +{
>  	arm_cpu_lowlevel_init();
>  
>  	arm_setup_stack(SAMA5D3_SRAM_BASE + SAMA5D3_SRAM_SIZE - 16);
>  
> +	relocate_to_current_adr();
> +	setup_c();
> +	barrier();
> +
> +	board_init();
> +}
> +
> +ENTRY_FUNCTION(start_sama5d3_xplained_ung8071, r0, r1, r2)
> +{
> +	void *fdt;
> +
> +	arm_setup_stack(SAMA5D3_SRAM_BASE + SAMA5D3_SRAM_SIZE - 16);
> +
> +	if (IS_ENABLED(CONFIG_DEBUG_LL))
> +		dbgu_init();
> +
>  	fdt = __dtb_z_at91_microchip_ksz9477_evb_start + get_runtime_offset();
>  
>  	barebox_arm_entry(SAMA5_DDRCS, SZ_256M, fdt);
> diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
> index 1401b8cfc9bb..e72e37c2bf9e 100644
> --- a/arch/arm/mach-at91/Kconfig
> +++ b/arch/arm/mach-at91/Kconfig
> @@ -200,6 +200,7 @@ config ARCH_SAMA5D3
>  	select SOC_SAMA5D3
>  	select HAS_MACB
>  	select HAVE_MACH_ARM_HEAD
> +	select HAVE_AT91_LOAD_BAREBOX_SRAM
>  
>  config ARCH_SAMA5D4
>  	bool "SAMA5D4"
> @@ -548,6 +549,7 @@ config MACH_MICROCHIP_KSZ9477_EVB
>  	select OFDEVICE
>  	select COMMON_CLK_OF_PROVIDER
>  	select ARM_USE_COMPRESSED_DTB
> +	select HAVE_AT91_BOOTSTRAP
>  	help
>  	  Select this if you are using Microchip's EVB-KSZ9477 Evaluation Kit.
>  
> diff --git a/arch/arm/mach-at91/include/mach/at91_pmc.h b/arch/arm/mach-at91/include/mach/at91_pmc.h
> index 4d60becefbab..dfc0fa63017f 100644
> --- a/arch/arm/mach-at91/include/mach/at91_pmc.h
> +++ b/arch/arm/mach-at91/include/mach/at91_pmc.h
> @@ -66,9 +66,17 @@
>  #define	AT91_CKGR_PLLAR		0x28			/* PLL A Register */
>  #define	AT91_CKGR_PLLBR		0x2c			/* PLL B Register */
>  #define		AT91_PMC_DIV		(0xff  <<  0)		/* Divider */
> +#define			AT91_PMC_DIV_BYPASS	(1 << 0)		/* Divider bypass */
>  #define		AT91_PMC_PLLCOUNT	(0x3f  <<  8)		/* PLL Counter */
>  #define		AT91_PMC_OUT		(3     << 14)		/* PLL Clock Frequency Range */
> +#define			AT91_PMC_OUT_0		(0 << 14)
> +#define			AT91_PMC_OUT_1		(1 << 14)
> +#define			AT91_PMC_OUT_2		(2 << 14)
> +#define			AT91_PMC_OUT_3		(3 << 14)
>  #define		AT91_PMC_MUL		(0x7ff << 16)		/* PLL Multiplier */
> +#define			AT91_PMC_MUL_(n)		(((n) << 16) & AT91_PMC_MUL)
> +#define		AT91_PMC3_MUL		(0x7f << 18)		/* PLL Multiplier [SAMA5 only]*/
> +#define			AT91_PMC3_MUL_(n)		(((n) << 18) & AT91_PMC3_MUL)
>  #define		AT91_PMC_USBDIV		(3     << 28)		/* USB Divisor (PLLB only) */
>  #define			AT91_PMC_USBDIV_1		(0 << 28)
>  #define			AT91_PMC_USBDIV_2		(1 << 28)
> diff --git a/arch/arm/mach-at91/include/mach/sama5d3.h b/arch/arm/mach-at91/include/mach/sama5d3.h
> index f0e53610c6c0..da6e825593e6 100644
> --- a/arch/arm/mach-at91/include/mach/sama5d3.h
> +++ b/arch/arm/mach-at91/include/mach/sama5d3.h
> @@ -87,6 +87,7 @@
>  #define SAMA5D3_BASE_PIOC	0xfffff600
>  #define SAMA5D3_BASE_PIOD	0xfffff800
>  #define SAMA5D3_BASE_PIOE	0xfffffa00
> +#define SAMA5D3_BASE_PMC	0xfffffc00
>  #define SAMA5D3_BASE_MPDDRC	0xffffea00
>  #define	SAMA5D3_BASE_HSMC	0xffffc000
>  #define SAMA5D3_BASE_RSTC	0xfffffe00
> diff --git a/images/Makefile.at91 b/images/Makefile.at91
> index 3f1dd57f6c58..3c3be0a30f66 100644
> --- a/images/Makefile.at91
> +++ b/images/Makefile.at91
> @@ -14,6 +14,11 @@ pblb-$(CONFIG_MACH_MICROCHIP_KSZ9477_EVB) += start_sama5d3_xplained_ung8071
>  FILE_barebox-microchip-ksz9477-evb.img = start_sama5d3_xplained_ung8071.pblb
>  at91-barebox-$(CONFIG_MACH_MICROCHIP_KSZ9477_EVB) += barebox-microchip-ksz9477-evb.img
>  
> +pblb-$(CONFIG_MACH_MICROCHIP_KSZ9477_EVB) += start_sama5d3_xplained_ung8071_boot_bin
> +MAX_PBL_IMAGE_SIZE_start_sama5d3_xplained_ung8071_boot_bin = 0x10000
> +FILE_barebox-microchip-ksz9477-evb-boot.bin.img = start_sama5d3_xplained_ung8071_boot_bin.pblb
> +at91-boot-bin-$(CONFIG_MACH_MICROCHIP_KSZ9477_EVB) += barebox-microchip-ksz9477-evb-boot.bin.img
> +
>  ifdef CONFIG_AT91_LOAD_BAREBOX_SRAM
>  image-y += $(at91-boot-bin-y)
>  else
> -- 
> 2.20.1
> 
> 
> _______________________________________________
> barebox mailing list
> barebox@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/barebox
> 

-- 
Roland Hieber                     | r.hieber@pengutronix.de     |
Pengutronix e.K.                  | https://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim | Phone: +49-5121-206917-5086 |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |

_______________________________________________
barebox mailing list
barebox@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/barebox

  reply	other threads:[~2019-04-01 12:38 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-01 10:18 [PATCH v3 00/15] ARM: at91: microchip-kz9477-evb: support first stage boot Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 01/15] LICENSES: add BSD-1-Clause license Ahmad Fatoum
2019-04-01 12:20   ` Roland Hieber
2019-04-21  9:03     ` Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 02/15] ARM: at91: import at91bootstrap's at91_ddrsdrc.h Ahmad Fatoum
2019-04-01 12:32   ` Roland Hieber
2019-04-01 13:36     ` Ahmad Fatoum
2019-04-01 14:23       ` Roland Hieber
2019-04-01 10:18 ` [PATCH v3 03/15] ARM: at91: migrate at91sam9_ddrsdr.h to use " Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 04/15] ARM: at91: replace at91sam9_ddrsdr.h with " Ahmad Fatoum
2019-04-02 17:25   ` Sam Ravnborg
2019-04-02 18:36     ` Ahmad Fatoum
2019-04-02 19:18       ` Sam Ravnborg
2019-04-03  7:22         ` Sascha Hauer
2019-04-03  9:54         ` Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 05/15] ARM: at91: watchdog: implement at91_wdt_disable Ahmad Fatoum
2019-04-02 17:38   ` Sam Ravnborg
2019-04-02 18:39     ` Ahmad Fatoum
2019-04-02 19:20       ` Sam Ravnborg
2019-04-01 10:18 ` [PATCH v3 06/15] ARM: at91: import lowlevel clock initialization from at91bootstrap Ahmad Fatoum
2019-04-02 17:42   ` Sam Ravnborg
2019-04-02 18:44     ` Ahmad Fatoum
2019-04-02 19:22       ` Sam Ravnborg
2019-04-01 10:18 ` [PATCH v3 07/15] ARM: at91: import early_udelay " Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 08/15] ARM: at91: import low level DDRAMC initialization code " Ahmad Fatoum
2019-04-03  7:48   ` Sascha Hauer
2019-04-01 10:18 ` [PATCH v3 09/15] ARM: at91: import lowlevel dbgu UART init " Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 10/15] images: at91: differentiate between first and second stage images Ahmad Fatoum
2019-04-02 17:49   ` Sam Ravnborg
2019-04-21  9:21     ` Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 11/15] ARM: at91: microchip-ksz9477-evb: use compressed DTB Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 12/15] ARM: dts: microchip-ksz9477-evb: add dummy first stage device tree Ahmad Fatoum
2019-04-01 10:18 ` [PATCH v3 13/15] ARM: at91: microchip-ksz9477-evb: implement first stage Ahmad Fatoum
2019-04-01 12:37   ` Roland Hieber [this message]
2019-04-01 13:37     ` Ahmad Fatoum
2019-04-03  7:58   ` Sascha Hauer
2019-04-01 10:18 ` [PATCH v3 14/15] ARM: at91: microchip-ksz9477: provide board code fallback Ahmad Fatoum
2019-04-02 18:01   ` Sam Ravnborg
2019-04-21  9:42     ` Ahmad Fatoum
2019-04-03  8:15   ` Sascha Hauer
2019-04-01 10:18 ` [PATCH v3 15/15] doc: microchip-ksz9477-evb: add documentation Ahmad Fatoum
2019-04-02 18:03   ` Sam Ravnborg
2019-04-02 18:06 ` [PATCH v3 00/15] ARM: at91: microchip-kz9477-evb: support first stage boot Sam Ravnborg

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190401123758.ubx75kuc6shvuht3@pengutronix.de \
    --to=rhi@pengutronix.de \
    --cc=a.fatoum@pengutronix.de \
    --cc=barebox@lists.infradead.org \
    --cc=sam@ravnborg.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox