Make the EFI earlycon driver be suitable for any linear framebuffers.
This should be helpful for early porting of boards with no other means of
output, like smartphones/tablets. There seems to be an issue with early_ioremap
function on ARM32, but I am unable to find the exact cause. It appears the mappings
returned by it are somehow incorrect, thus the driver is disabled on ARM. EFI early
console was disabled on IA64 previously because of missing early_memremap_prot,
and this is inherited to this driver.
This patch also changes behavior on EFI systems, by selecting the mapping type
based on if the framebuffer region intersects with system RAM. If it does, it's
common sense that it should be in RAM as a whole, and so the system RAM mapping is
used. It was tested to be working on my PC (Intel Z490 platform), as well as several
ARM64 boards (Samsung Galaxy S9 (Exynos), iPad Air 2, Xiaomi Mi Pad 4, ...).
Markuss Broks (2):
drivers: serial: earlycon: Pass device-tree node
efi: earlycon: Add support for generic framebuffers and move to fbdev
subsystem
v1 -> v2:
- a new patch correcting serial/earlycon.c argument name to "offset" instead
of "node"
- move IA64 exclusion from EFI earlycon Kconfig to earlycon driver Kconfig
(IA64 has no early_memremap_prot)
- move driver from fbdev to console subsystem
- select EFI earlycon by default
- fetch stride manually from device-tree, as on some devices it seems stride
doesn't match the horizontal resolution * bpp.
- use saner format (e.g. 1920x1080x32 instead of 1920,1080,32).
Markuss Broks (3):
drivers: serial: earlycon: Pass device-tree node
efi: earlycon: move to video/console to prepare for changes
efi: earlycon: Add support for generic framebuffers
.../admin-guide/kernel-parameters.txt | 12 +-
MAINTAINERS | 5 +
drivers/firmware/efi/Kconfig | 7 +-
drivers/firmware/efi/Makefile | 1 -
drivers/firmware/efi/earlycon.c | 246 --------------
drivers/tty/serial/earlycon.c | 3 +
drivers/video/console/Kconfig | 11 +
drivers/video/console/Makefile | 1 +
drivers/video/console/earlycon.c | 305 ++++++++++++++++++
include/linux/serial_core.h | 1 +
10 files changed, 336 insertions(+), 256 deletions(-)
delete mode 100644 drivers/firmware/efi/earlycon.c
create mode 100644 drivers/video/console/earlycon.c
--
2.39.0
This would make the next patch in series with this one to
show a clear diff, instead of just removing the previous
driver and creating a new one.
Signed-off-by: Markuss Broks <[email protected]>
---
drivers/{firmware/efi => video/console}/earlycon.c | 0
1 file changed, 0 insertions(+), 0 deletions(-)
rename drivers/{firmware/efi => video/console}/earlycon.c (100%)
diff --git a/drivers/firmware/efi/earlycon.c b/drivers/video/console/earlycon.c
similarity index 100%
rename from drivers/firmware/efi/earlycon.c
rename to drivers/video/console/earlycon.c
--
2.39.0
Add early console support for generic linear framebuffer devices.
This driver supports probing from cmdline early parameters
or from the device-tree using information in simple-framebuffer node.
The EFI functionality should be retained in whole.
The driver was disabled on ARM because of a bug in early_ioremap
implementation on ARM and on IA64 because of lack of early_memremap_prot.
Signed-off-by: Markuss Broks <[email protected]>
---
.../admin-guide/kernel-parameters.txt | 12 +-
MAINTAINERS | 5 +
drivers/firmware/efi/Kconfig | 7 +-
drivers/firmware/efi/Makefile | 1 -
drivers/video/console/Kconfig | 11 +
drivers/video/console/Makefile | 1 +
drivers/video/console/earlycon.c | 247 +++++++++++-------
7 files changed, 180 insertions(+), 104 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6cfa6e3996cf..3bfac80f9075 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1302,12 +1302,9 @@
specified address. The serial port must already be
setup and configured. Options are not yet supported.
- efifb,[options]
+ efifb
Start an early, unaccelerated console on the EFI
- memory mapped framebuffer (if available). On cache
- coherent non-x86 systems that use system memory for
- the framebuffer, pass the 'ram' option so that it is
- mapped with the correct attributes.
+ memory mapped framebuffer (if available).
linflex,<addr>
Use early console provided by Freescale LINFlexD UART
@@ -1315,6 +1312,11 @@
address must be provided, and the serial port must
already be setup and configured.
+ simplefb,<addr>,<width>x<height>x<bpp>
+ Use early console with simple framebuffer that is
+ pre-initialized by firmware. A valid base address,
+ width, height and pixel size must be provided.
+
earlyprintk= [X86,SH,ARM,M68k,S390]
earlyprintk=vga
earlyprintk=sclp
diff --git a/MAINTAINERS b/MAINTAINERS
index 30e032abd196..270a4eecadec 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7373,6 +7373,11 @@ Q: http://patchwork.linuxtv.org/project/linux-media/list/
T: git git://linuxtv.org/anttip/media_tree.git
F: drivers/media/tuners/e4000*
+EARLY CONSOLE FRAMEBUFFER DRIVER
+M: Markuss Broks <[email protected]>
+S: Maintained
+F: drivers/video/console/earlycon.c
+
EARTH_PT1 MEDIA DRIVER
M: Akihiro Tsukada <[email protected]>
L: [email protected]
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 043ca31c114e..cedb718fab78 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -223,10 +223,9 @@ config EFI_DISABLE_PCI_DMA
may be used to override this option.
config EFI_EARLYCON
- def_bool y
- depends on SERIAL_EARLYCON && !ARM && !IA64
- select FONT_SUPPORT
- select ARCH_USE_MEMREMAP_PROT
+ bool "EFI early console support"
+ select FB_EARLYCON
+ default y
config EFI_CUSTOM_SSDT_OVERLAYS
bool "Load custom ACPI SSDT overlay from an EFI variable"
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index b51f2a4c821e..ec46351ce79b 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -38,6 +38,5 @@ obj-$(CONFIG_ARM64) += $(arm-obj-y)
riscv-obj-$(CONFIG_EFI) := efi-init.o riscv-runtime.o
obj-$(CONFIG_RISCV) += $(riscv-obj-y)
obj-$(CONFIG_EFI_CAPSULE_LOADER) += capsule-loader.o
-obj-$(CONFIG_EFI_EARLYCON) += earlycon.o
obj-$(CONFIG_UEFI_CPER_ARM) += cper-arm.o
obj-$(CONFIG_UEFI_CPER_X86) += cper-x86.o
diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
index 22cea5082ac4..6edfeddfe5ec 100644
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig
@@ -70,6 +70,17 @@ config DUMMY_CONSOLE_ROWS
monitor.
Select 25 if you use a 640x480 resolution by default.
+config FB_EARLYCON
+ bool "Generic framebuffer early console"
+ depends on SERIAL_EARLYCON && !ARM && !IA64
+ select FONT_SUPPORT
+ select ARCH_USE_MEMREMAP_PROT
+ help
+ Say Y here if you want early console support for firmware established
+ linear framebuffer. Unless you are using EFI framebuffer, you need to
+ specify framebuffer geometry and address in device-tree or in kernel
+ command line.
+
config FRAMEBUFFER_CONSOLE
bool "Framebuffer Console support"
depends on FB && !UML
diff --git a/drivers/video/console/Makefile b/drivers/video/console/Makefile
index db07b784bd2c..7818faee587f 100644
--- a/drivers/video/console/Makefile
+++ b/drivers/video/console/Makefile
@@ -9,4 +9,5 @@ obj-$(CONFIG_STI_CONSOLE) += sticon.o sticore.o
obj-$(CONFIG_VGA_CONSOLE) += vgacon.o
obj-$(CONFIG_MDA_CONSOLE) += mdacon.o
+obj-$(CONFIG_FB_EARLYCON) += earlycon.o
obj-$(CONFIG_FB_STI) += sticore.o
diff --git a/drivers/video/console/earlycon.c b/drivers/video/console/earlycon.c
index 4d6c5327471a..afba921e2222 100644
--- a/drivers/video/console/earlycon.c
+++ b/drivers/video/console/earlycon.c
@@ -1,118 +1,122 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2013 Intel Corporation; author Matt Fleming
+ * Copyright (C) 2022 Markuss Broks <[email protected]>
*/
+#include <asm/early_ioremap.h>
#include <linux/console.h>
#include <linux/efi.h>
#include <linux/font.h>
#include <linux/io.h>
#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/of.h>
+#include <linux/of_fdt.h>
#include <linux/serial_core.h>
#include <linux/screen_info.h>
-#include <asm/early_ioremap.h>
+struct fb_earlycon {
+ u32 x, y, curr_x, curr_y, depth, stride;
+ size_t size;
+ phys_addr_t phys_base;
+ void __iomem *virt_base;
+};
-static const struct console *earlycon_console __initdata;
+static const struct console *earlycon_console __initconst;
+static struct fb_earlycon info;
static const struct font_desc *font;
-static u32 efi_x, efi_y;
-static u64 fb_base;
-static bool fb_wb;
-static void *efi_fb;
-/*
- * EFI earlycon needs to use early_memremap() to map the framebuffer.
- * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
- * memremap() should be used instead. memremap() will be available after
- * paging_init() which is earlier than initcall callbacks. Thus adding this
- * early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
- */
-static int __init efi_earlycon_remap_fb(void)
+static int __init simplefb_earlycon_remap_fb(void)
{
- /* bail if there is no bootconsole or it was unregistered already */
- if (!earlycon_console || !console_is_registered(earlycon_console))
+ unsigned long mapping;
+ /* bail if there is no bootconsole or it has been disabled already */
+ if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
return 0;
- efi_fb = memremap(fb_base, screen_info.lfb_size,
- fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
+ if (region_intersects(info.phys_base, info.size,
+ IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE) == REGION_INTERSECTS)
+ mapping = MEMREMAP_WB;
+ else
+ mapping = MEMREMAP_WC;
+
+ info.virt_base = memremap(info.phys_base, info.size, mapping);
- return efi_fb ? 0 : -ENOMEM;
+ return info.virt_base ? 0 : -ENOMEM;
}
-early_initcall(efi_earlycon_remap_fb);
+early_initcall(simplefb_earlycon_remap_fb);
-static int __init efi_earlycon_unmap_fb(void)
+static int __init simplefb_earlycon_unmap_fb(void)
{
- /* unmap the bootconsole fb unless keep_bootcon left it registered */
- if (efi_fb && !console_is_registered(earlycon_console))
- memunmap(efi_fb);
+ /* unmap the bootconsole fb unless keep_bootcon has left it enabled */
+ if (info.virt_base && !(earlycon_console->flags & CON_ENABLED))
+ memunmap(info.virt_base);
return 0;
}
-late_initcall(efi_earlycon_unmap_fb);
+late_initcall(simplefb_earlycon_unmap_fb);
-static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
+static __ref void *simplefb_earlycon_map(unsigned long start, unsigned long len)
{
pgprot_t fb_prot;
- if (efi_fb)
- return efi_fb + start;
+ if (info.virt_base)
+ return info.virt_base + start;
- fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
- return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
+ fb_prot = PAGE_KERNEL;
+ return early_memremap_prot(info.phys_base + start, len, pgprot_val(fb_prot));
}
-static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
+static __ref void simplefb_earlycon_unmap(void *addr, unsigned long len)
{
- if (efi_fb)
+ if (info.virt_base)
return;
early_memunmap(addr, len);
}
-static void efi_earlycon_clear_scanline(unsigned int y)
+static void simplefb_earlycon_clear_scanline(unsigned int y)
{
unsigned long *dst;
u16 len;
- len = screen_info.lfb_linelength;
- dst = efi_earlycon_map(y*len, len);
+ len = info.stride;
+ dst = simplefb_earlycon_map(y * len, len);
if (!dst)
return;
memset(dst, 0, len);
- efi_earlycon_unmap(dst, len);
+ simplefb_earlycon_unmap(dst, len);
}
-static void efi_earlycon_scroll_up(void)
+static void simplefb_earlycon_scroll_up(void)
{
unsigned long *dst, *src;
u16 len;
u32 i, height;
- len = screen_info.lfb_linelength;
- height = screen_info.lfb_height;
+ len = info.stride;
+ height = info.y;
for (i = 0; i < height - font->height; i++) {
- dst = efi_earlycon_map(i*len, len);
+ dst = simplefb_earlycon_map(i * len, len);
if (!dst)
return;
- src = efi_earlycon_map((i + font->height) * len, len);
+ src = simplefb_earlycon_map((i + font->height) * len, len);
if (!src) {
- efi_earlycon_unmap(dst, len);
+ simplefb_earlycon_unmap(dst, len);
return;
}
memmove(dst, src, len);
- efi_earlycon_unmap(src, len);
- efi_earlycon_unmap(dst, len);
+ simplefb_earlycon_unmap(src, len);
+ simplefb_earlycon_unmap(dst, len);
}
}
-static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
+static void simplefb_earlycon_write_char(u8 *dst, unsigned char c, unsigned int h)
{
- const u32 color_black = 0x00000000;
- const u32 color_white = 0x00ffffff;
const u8 *src;
int m, n, bytes;
u8 x;
@@ -124,23 +128,21 @@ static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
n = m % 8;
x = *(src + m / 8);
if ((x >> (7 - n)) & 1)
- *dst = color_white;
+ memset(dst, 0xff, (info.depth / 8));
else
- *dst = color_black;
- dst++;
+ memset(dst, 0, (info.depth / 8));
+ dst += (info.depth / 8);
}
}
static void
-efi_earlycon_write(struct console *con, const char *str, unsigned int num)
+simplefb_earlycon_write(struct console *con, const char *str, unsigned int num)
{
- struct screen_info *si;
unsigned int len;
const char *s;
void *dst;
- si = &screen_info;
- len = si->lfb_linelength;
+ len = info.stride;
while (num) {
unsigned int linemax;
@@ -152,95 +154,152 @@ efi_earlycon_write(struct console *con, const char *str, unsigned int num)
count++;
}
- linemax = (si->lfb_width - efi_x) / font->width;
+ linemax = (info.x - info.curr_x) / font->width;
if (count > linemax)
count = linemax;
for (h = 0; h < font->height; h++) {
unsigned int n, x;
- dst = efi_earlycon_map((efi_y + h) * len, len);
+ dst = simplefb_earlycon_map((info.curr_y + h) * len, len);
if (!dst)
return;
s = str;
n = count;
- x = efi_x;
+ x = info.curr_x;
while (n-- > 0) {
- efi_earlycon_write_char(dst + x*4, *s, h);
+ simplefb_earlycon_write_char(dst + (x * 4), *s, h);
x += font->width;
s++;
}
- efi_earlycon_unmap(dst, len);
+ simplefb_earlycon_unmap(dst, len);
}
num -= count;
- efi_x += count * font->width;
+ info.curr_x += count * font->width;
str += count;
if (num > 0 && *s == '\n') {
- efi_x = 0;
- efi_y += font->height;
+ info.curr_x = 0;
+ info.curr_y += font->height;
str++;
num--;
}
- if (efi_x + font->width > si->lfb_width) {
- efi_x = 0;
- efi_y += font->height;
+ if (info.curr_x + font->width > info.x) {
+ info.curr_x = 0;
+ info.curr_y += font->height;
}
- if (efi_y + font->height > si->lfb_height) {
+ if (info.curr_y + font->height > info.y) {
u32 i;
- efi_y -= font->height;
- efi_earlycon_scroll_up();
+ info.curr_y -= font->height;
+ simplefb_earlycon_scroll_up();
for (i = 0; i < font->height; i++)
- efi_earlycon_clear_scanline(efi_y + i);
+ simplefb_earlycon_clear_scanline(info.curr_y + i);
}
}
}
-static int __init efi_earlycon_setup(struct earlycon_device *device,
- const char *opt)
+static int __init simplefb_earlycon_setup_common(struct earlycon_device *device,
+ const char *opt)
{
- struct screen_info *si;
- u16 xres, yres;
- u32 i;
+ int i;
+
+ info.size = info.x * info.y * (info.depth / 8);
+
+ font = get_default_font(info.x, info.y, -1, -1);
+ if (!font)
+ return -ENODEV;
+
+ info.curr_y = rounddown(info.y, font->height) - font->height;
+ for (i = 0; i < (info.y - info.curr_y) / font->height; i++)
+ simplefb_earlycon_scroll_up();
+
+ device->con->write = simplefb_earlycon_write;
+ earlycon_console = device->con;
+ return 0;
+}
+
+static int __init simplefb_earlycon_setup(struct earlycon_device *device,
+ const char *opt)
+{
+ struct uart_port *port = &device->port;
+ int ret;
+
+ if (!port->mapbase)
+ return -ENODEV;
+
+ info.phys_base = port->mapbase;
+ ret = sscanf(device->options, "%ux%ux%u", &info.x, &info.y, &info.depth);
+ if (ret != 3)
+ return -ENODEV;
+
+ info.stride = info.x * (info.depth / 8);
+
+ return simplefb_earlycon_setup_common(device, opt);
+}
+
+EARLYCON_DECLARE(simplefb, simplefb_earlycon_setup);
+
+#ifdef CONFIG_EFI_EARLYCON
+static int __init simplefb_earlycon_setup_efi(struct earlycon_device *device,
+ const char *opt)
+{
if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
return -ENODEV;
- fb_base = screen_info.lfb_base;
+ info.phys_base = screen_info.lfb_base;
if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
- fb_base |= (u64)screen_info.ext_lfb_base << 32;
+ info.phys_base |= (u64)screen_info.ext_lfb_base << 32;
- fb_wb = opt && !strcmp(opt, "ram");
+ info.x = screen_info.lfb_width;
+ info.y = screen_info.lfb_height;
+ info.depth = screen_info.lfb_depth;
+ info.stride = screen_info.lfb_linelength;
- si = &screen_info;
- xres = si->lfb_width;
- yres = si->lfb_height;
+ return simplefb_earlycon_setup_common(device, opt);
+}
- /*
- * efi_earlycon_write_char() implicitly assumes a framebuffer with
- * 32 bits per pixel.
- */
- if (si->lfb_depth != 32)
+EARLYCON_DECLARE(efifb, simplefb_earlycon_setup_efi);
+#endif
+
+#ifdef CONFIG_OF_EARLY_FLATTREE
+static int __init simplefb_earlycon_setup_of(struct earlycon_device *device,
+ const char *opt)
+{
+ struct uart_port *port = &device->port;
+ const __be32 *val;
+
+ if (!port->mapbase)
return -ENODEV;
- font = get_default_font(xres, yres, -1, -1);
- if (!font)
+ info.phys_base = port->mapbase;
+
+ val = of_get_flat_dt_prop(device->node, "width", NULL);
+ if (!val)
return -ENODEV;
+ info.x = be32_to_cpu(*val);
- efi_y = rounddown(yres, font->height) - font->height;
- for (i = 0; i < (yres - efi_y) / font->height; i++)
- efi_earlycon_scroll_up();
+ val = of_get_flat_dt_prop(device->node, "height", NULL);
+ if (!val)
+ return -ENODEV;
+ info.y = be32_to_cpu(*val);
- device->con->write = efi_earlycon_write;
- earlycon_console = device->con;
- return 0;
+ val = of_get_flat_dt_prop(device->node, "stride", NULL);
+ if (!val)
+ return -ENODEV;
+ info.stride = be32_to_cpu(*val);
+ info.depth = (info.stride / info.x) * 8;
+
+ return simplefb_earlycon_setup_common(device, opt);
}
-EARLYCON_DECLARE(efifb, efi_earlycon_setup);
+
+OF_EARLYCON_DECLARE(simplefb, "simple-framebuffer", simplefb_earlycon_setup_of);
+#endif
--
2.39.0
(cc Andy)
On Wed, 21 Dec 2022 at 11:54, Markuss Broks <[email protected]> wrote:
>
> Make the EFI earlycon driver be suitable for any linear framebuffers.
> This should be helpful for early porting of boards with no other means of
> output, like smartphones/tablets. There seems to be an issue with early_ioremap
> function on ARM32, but I am unable to find the exact cause. It appears the mappings
> returned by it are somehow incorrect, thus the driver is disabled on ARM.
The reason that this driver is disabled on ARM is because the struct
screen_info is not populated early enough, as it is retrieved from a
UEFI configuration table.
early_ioremap() works fine on ARM as long as they mapping is torn down
before paging_init()
> EFI early
> console was disabled on IA64 previously because of missing early_memremap_prot,
> and this is inherited to this driver.
>
> This patch also changes
"This patch also changes ..." is usually a strong hint to self that
the patches need to be split up.
> behavior on EFI systems, by selecting the mapping type
> based on if the framebuffer region intersects with system RAM. If it does, it's
> common sense that it should be in RAM as a whole, and so the system RAM mapping is
> used. It was tested to be working on my PC (Intel Z490 platform), as well as several
> ARM64 boards (Samsung Galaxy S9 (Exynos), iPad Air 2, Xiaomi Mi Pad 4, ...).
>
> Markuss Broks (2):
> drivers: serial: earlycon: Pass device-tree node
> efi: earlycon: Add support for generic framebuffers and move to fbdev
> subsystem
>
>
> v1 -> v2:
>
> - a new patch correcting serial/earlycon.c argument name to "offset" instead
> of "node"
> - move IA64 exclusion from EFI earlycon Kconfig to earlycon driver Kconfig
> (IA64 has no early_memremap_prot)
> - move driver from fbdev to console subsystem
> - select EFI earlycon by default
> - fetch stride manually from device-tree, as on some devices it seems stride
> doesn't match the horizontal resolution * bpp.
> - use saner format (e.g. 1920x1080x32 instead of 1920,1080,32).
>
>
> Markuss Broks (3):
> drivers: serial: earlycon: Pass device-tree node
> efi: earlycon: move to video/console to prepare for changes
> efi: earlycon: Add support for generic framebuffers
>
> .../admin-guide/kernel-parameters.txt | 12 +-
> MAINTAINERS | 5 +
> drivers/firmware/efi/Kconfig | 7 +-
> drivers/firmware/efi/Makefile | 1 -
> drivers/firmware/efi/earlycon.c | 246 --------------
> drivers/tty/serial/earlycon.c | 3 +
> drivers/video/console/Kconfig | 11 +
> drivers/video/console/Makefile | 1 +
> drivers/video/console/earlycon.c | 305 ++++++++++++++++++
> include/linux/serial_core.h | 1 +
> 10 files changed, 336 insertions(+), 256 deletions(-)
> delete mode 100644 drivers/firmware/efi/earlycon.c
> create mode 100644 drivers/video/console/earlycon.c
>
> --
> 2.39.0
>
Hi Ard,
On 12/23/22 16:42, Ard Biesheuvel wrote:
> (cc Andy)
>
>
> On Wed, 21 Dec 2022 at 11:54, Markuss Broks <[email protected]> wrote:
>> Make the EFI earlycon driver be suitable for any linear framebuffers.
>> This should be helpful for early porting of boards with no other means of
>> output, like smartphones/tablets. There seems to be an issue with early_ioremap
>> function on ARM32, but I am unable to find the exact cause. It appears the mappings
>> returned by it are somehow incorrect, thus the driver is disabled on ARM.
> The reason that this driver is disabled on ARM is because the struct
> screen_info is not populated early enough, as it is retrieved from a
> UEFI configuration table.
I believe I must be hitting some other bug then, since my driver should
not use `struct screen_info` when the arguments are specified manually
(e.g. in device-tree or in kernel command line options), and it still is
broken on ARM when they are. I got it to work on ARM when I moved the
early console initialization later into the kernel booting process, but
that mostly defeats the purpose of early console driver, I believe. I've
been thinking that it could be some stuff not getting initialized early
enough indeed, but I've got no clue what could it be.
>
> early_ioremap() works fine on ARM as long as they mapping is torn down
> before paging_init()
>
>> EFI early
>> console was disabled on IA64 previously because of missing early_memremap_prot,
>> and this is inherited to this driver.
>>
>> This patch also changes
> "This patch also changes ..." is usually a strong hint to self that
> the patches need to be split up.
>
>> behavior on EFI systems, by selecting the mapping type
>> based on if the framebuffer region intersects with system RAM. If it does, it's
>> common sense that it should be in RAM as a whole, and so the system RAM mapping is
>> used. It was tested to be working on my PC (Intel Z490 platform), as well as several
>> ARM64 boards (Samsung Galaxy S9 (Exynos), iPad Air 2, Xiaomi Mi Pad 4, ...).
>>
>> Markuss Broks (2):
>> drivers: serial: earlycon: Pass device-tree node
>> efi: earlycon: Add support for generic framebuffers and move to fbdev
>> subsystem
>>
>>
>> v1 -> v2:
>>
>> - a new patch correcting serial/earlycon.c argument name to "offset" instead
>> of "node"
>> - move IA64 exclusion from EFI earlycon Kconfig to earlycon driver Kconfig
>> (IA64 has no early_memremap_prot)
>> - move driver from fbdev to console subsystem
>> - select EFI earlycon by default
>> - fetch stride manually from device-tree, as on some devices it seems stride
>> doesn't match the horizontal resolution * bpp.
>> - use saner format (e.g. 1920x1080x32 instead of 1920,1080,32).
>>
>>
>> Markuss Broks (3):
>> drivers: serial: earlycon: Pass device-tree node
>> efi: earlycon: move to video/console to prepare for changes
>> efi: earlycon: Add support for generic framebuffers
>>
>> .../admin-guide/kernel-parameters.txt | 12 +-
>> MAINTAINERS | 5 +
>> drivers/firmware/efi/Kconfig | 7 +-
>> drivers/firmware/efi/Makefile | 1 -
>> drivers/firmware/efi/earlycon.c | 246 --------------
>> drivers/tty/serial/earlycon.c | 3 +
>> drivers/video/console/Kconfig | 11 +
>> drivers/video/console/Makefile | 1 +
>> drivers/video/console/earlycon.c | 305 ++++++++++++++++++
>> include/linux/serial_core.h | 1 +
>> 10 files changed, 336 insertions(+), 256 deletions(-)
>> delete mode 100644 drivers/firmware/efi/earlycon.c
>> create mode 100644 drivers/video/console/earlycon.c
>>
>> --
>> 2.39.0
>>
- Markuss
P.S. Just noticed I forgot to Ctrl^S the cover letter before saving...
The main change v3 does is separate the moving action and edit action
into two separate commits, I don't think there're more major changes.
With v4 I'd try to attach the proper version log.
On Fri, Dec 23, 2022 at 03:42:33PM +0100, Ard Biesheuvel wrote:
> (cc Andy)
I believe there are two reasons I'm Cc'ed now:
- the Cc was forgotten. because I remember reviewing some parts
of this contribution
- this conflicts (to some extent) with my patch that speeds up
the scrolling
For the first it's obvious what to do, I think Markuss can include me
in his v4.
For the second I don't see the functional clash. The scrolling in this
series is not anyhow optimized. I think my patch should go first as
- it is less intrusive
- it has been tested, or can be tested easily
Tell me if I'm missing something here.
> On Wed, 21 Dec 2022 at 11:54, Markuss Broks <[email protected]> wrote:
> >
> > Make the EFI earlycon driver be suitable for any linear framebuffers.
> > This should be helpful for early porting of boards with no other means of
> > output, like smartphones/tablets. There seems to be an issue with early_ioremap
> > function on ARM32, but I am unable to find the exact cause. It appears the mappings
> > returned by it are somehow incorrect, thus the driver is disabled on ARM.
>
> The reason that this driver is disabled on ARM is because the struct
> screen_info is not populated early enough, as it is retrieved from a
> UEFI configuration table.
>
> early_ioremap() works fine on ARM as long as they mapping is torn down
> before paging_init()
>
> > EFI early
> > console was disabled on IA64 previously because of missing early_memremap_prot,
> > and this is inherited to this driver.
> >
> > This patch also changes
>
> "This patch also changes ..." is usually a strong hint to self that
> the patches need to be split up.
>
> > behavior on EFI systems, by selecting the mapping type
> > based on if the framebuffer region intersects with system RAM. If it does, it's
> > common sense that it should be in RAM as a whole, and so the system RAM mapping is
> > used. It was tested to be working on my PC (Intel Z490 platform), as well as several
> > ARM64 boards (Samsung Galaxy S9 (Exynos), iPad Air 2, Xiaomi Mi Pad 4, ...).
--
With Best Regards,
Andy Shevchenko
On Wed, 28 Dec 2022 at 15:04, Andy Shevchenko
<[email protected]> wrote:
>
> On Fri, Dec 23, 2022 at 03:42:33PM +0100, Ard Biesheuvel wrote:
> > (cc Andy)
>
> I believe there are two reasons I'm Cc'ed now:
> - the Cc was forgotten. because I remember reviewing some parts
> of this contribution
> - this conflicts (to some extent) with my patch that speeds up
> the scrolling
>
> For the first it's obvious what to do, I think Markuss can include me
> in his v4.
>
> For the second I don't see the functional clash. The scrolling in this
> series is not anyhow optimized. I think my patch should go first as
> - it is less intrusive
> - it has been tested, or can be tested easily
>
> Tell me if I'm missing something here.
>
Thanks for your input.
On Fri, 23 Dec 2022 at 15:58, Markuss Broks <[email protected]> wrote:
>
> Hi Ard,
>
> On 12/23/22 16:42, Ard Biesheuvel wrote:
> > (cc Andy)
> >
> >
> > On Wed, 21 Dec 2022 at 11:54, Markuss Broks <[email protected]> wrote:
> >> Make the EFI earlycon driver be suitable for any linear framebuffers.
> >> This should be helpful for early porting of boards with no other means of
> >> output, like smartphones/tablets. There seems to be an issue with early_ioremap
> >> function on ARM32, but I am unable to find the exact cause. It appears the mappings
> >> returned by it are somehow incorrect, thus the driver is disabled on ARM.
> > The reason that this driver is disabled on ARM is because the struct
> > screen_info is not populated early enough, as it is retrieved from a
> > UEFI configuration table.
>
> I believe I must be hitting some other bug then, since my driver should
> not use `struct screen_info` when the arguments are specified manually
> (e.g. in device-tree or in kernel command line options), and it still is
> broken on ARM when they are.
Define 'broken'
> I got it to work on ARM when I moved the
> early console initialization later into the kernel booting process, but
> that mostly defeats the purpose of early console driver, I believe. I've
> been thinking that it could be some stuff not getting initialized early
> enough indeed, but I've got no clue what could it be.
>
This is likely due to the fact that the ARM init code sets up the PTE
bits for various memory types, and using them beforehand is likely to
result in problems.