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Message-ID: <aSQlqZPTAXHvTnrG@r1chard>
Date: Mon, 24 Nov 2025 17:30:17 +0800
From: Richard Lyu <richard.lyu@...e.com>
To: Thomas Zimmermann <tzimmermann@...e.de>, ardb@...nel.org,
javierm@...hat.com, arnd@...db.de
Cc: x86@...nel.org, linux-arm-kernel@...ts.infradead.org,
linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
loongarch@...ts.linux.dev, linux-riscv@...ts.infradead.org,
dri-devel@...ts.freedesktop.org, linux-hyperv@...r.kernel.org,
linux-pci@...r.kernel.org, linux-fbdev@...r.kernel.org
Subject: Re: [PATCH 2/6] efi: sysfb_efi: Reduce number of references to
global screen_info
Reviewed-by: Richard Lyu <richard.lyu@...e.com>
On 2025/11/21 14:36, Thomas Zimmermann wrote:
> Replace usage of global screen_info with local pointers. This will
> later reduce churn when screen_info is being moved.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@...e.de>
> ---
> drivers/firmware/efi/sysfb_efi.c | 81 ++++++++++++++++---------------
> drivers/firmware/sysfb.c | 4 +-
> drivers/firmware/sysfb_simplefb.c | 2 +-
> include/linux/sysfb.h | 9 ++--
> 4 files changed, 51 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/firmware/efi/sysfb_efi.c b/drivers/firmware/efi/sysfb_efi.c
> index 1e509595ac03..8e0f9d08397f 100644
> --- a/drivers/firmware/efi/sysfb_efi.c
> +++ b/drivers/firmware/efi/sysfb_efi.c
> @@ -92,7 +92,7 @@ void efifb_setup_from_dmi(struct screen_info *si, const char *opt)
> })
>
> #ifdef CONFIG_EFI
> -static int __init efifb_set_system(const struct dmi_system_id *id)
> +static int __init efifb_set_system(struct screen_info *si, const struct dmi_system_id *id)
> {
> struct efifb_dmi_info *info = id->driver_data;
>
> @@ -101,14 +101,14 @@ static int __init efifb_set_system(const struct dmi_system_id *id)
> return 0;
>
> /* Trust the bootloader over the DMI tables */
> - if (screen_info.lfb_base == 0) {
> + if (si->lfb_base == 0) {
> #if defined(CONFIG_PCI)
> struct pci_dev *dev = NULL;
> int found_bar = 0;
> #endif
> if (info->base) {
> - screen_info.lfb_base = choose_value(info->base,
> - screen_info.lfb_base, OVERRIDE_BASE,
> + si->lfb_base = choose_value(info->base,
> + si->lfb_base, OVERRIDE_BASE,
> info->flags);
>
> #if defined(CONFIG_PCI)
> @@ -135,49 +135,53 @@ static int __init efifb_set_system(const struct dmi_system_id *id)
>
> start = pci_resource_start(dev, i);
> end = pci_resource_end(dev, i);
> - if (screen_info.lfb_base >= start &&
> - screen_info.lfb_base < end) {
> + if (si->lfb_base >= start && si->lfb_base < end) {
> found_bar = 1;
> break;
> }
> }
> }
> if (!found_bar)
> - screen_info.lfb_base = 0;
> + si->lfb_base = 0;
> #endif
> }
> }
> - if (screen_info.lfb_base) {
> - screen_info.lfb_linelength = choose_value(info->stride,
> - screen_info.lfb_linelength, OVERRIDE_STRIDE,
> + if (si->lfb_base) {
> + si->lfb_linelength = choose_value(info->stride,
> + si->lfb_linelength, OVERRIDE_STRIDE,
> info->flags);
> - screen_info.lfb_width = choose_value(info->width,
> - screen_info.lfb_width, OVERRIDE_WIDTH,
> + si->lfb_width = choose_value(info->width,
> + si->lfb_width, OVERRIDE_WIDTH,
> info->flags);
> - screen_info.lfb_height = choose_value(info->height,
> - screen_info.lfb_height, OVERRIDE_HEIGHT,
> + si->lfb_height = choose_value(info->height,
> + si->lfb_height, OVERRIDE_HEIGHT,
> info->flags);
> - if (screen_info.orig_video_isVGA == 0)
> - screen_info.orig_video_isVGA = VIDEO_TYPE_EFI;
> + if (si->orig_video_isVGA == 0)
> + si->orig_video_isVGA = VIDEO_TYPE_EFI;
> } else {
> - screen_info.lfb_linelength = 0;
> - screen_info.lfb_width = 0;
> - screen_info.lfb_height = 0;
> - screen_info.orig_video_isVGA = 0;
> + si->lfb_linelength = 0;
> + si->lfb_width = 0;
> + si->lfb_height = 0;
> + si->orig_video_isVGA = 0;
> return 0;
> }
>
> printk(KERN_INFO "efifb: dmi detected %s - framebuffer at 0x%08x "
> "(%dx%d, stride %d)\n", id->ident,
> - screen_info.lfb_base, screen_info.lfb_width,
> - screen_info.lfb_height, screen_info.lfb_linelength);
> + si->lfb_base, si->lfb_width,
> + si->lfb_height, si->lfb_linelength);
>
> return 1;
> }
>
> +static int __init efifb_set_system_callback(const struct dmi_system_id *id)
> +{
> + return efifb_set_system(&screen_info, id);
> +}
> +
> #define EFIFB_DMI_SYSTEM_ID(vendor, name, enumid) \
> { \
> - efifb_set_system, \
> + efifb_set_system_callback, \
> name, \
> { \
> DMI_MATCH(DMI_BIOS_VENDOR, vendor), \
> @@ -284,12 +288,13 @@ static const struct dmi_system_id efifb_dmi_swap_width_height[] __initconst = {
> {},
> };
>
> -static bool efifb_overlaps_pci_range(const struct of_pci_range *range)
> +static bool efifb_overlaps_pci_range(const struct screen_info *si,
> + const struct of_pci_range *range)
> {
> - u64 fb_base = screen_info.lfb_base;
> + u64 fb_base = si->lfb_base;
>
> - if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> - fb_base |= (u64)(unsigned long)screen_info.ext_lfb_base << 32;
> + if (si->capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> + fb_base |= (u64)(unsigned long)si->ext_lfb_base << 32;
>
> return fb_base >= range->cpu_addr &&
> fb_base < (range->cpu_addr + range->size);
> @@ -311,7 +316,7 @@ static struct device_node *find_pci_overlap_node(void)
> }
>
> for_each_of_pci_range(&parser, &range)
> - if (efifb_overlaps_pci_range(&range))
> + if (efifb_overlaps_pci_range(&screen_info, &range))
> return np;
> }
> return NULL;
> @@ -349,25 +354,25 @@ static const struct fwnode_operations efifb_fwnode_ops = {
>
> static struct fwnode_handle efifb_fwnode;
>
> -__init void sysfb_apply_efi_quirks(void)
> +__init void sysfb_apply_efi_quirks(struct screen_info *si)
> {
> - if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI ||
> - !(screen_info.capabilities & VIDEO_CAPABILITY_SKIP_QUIRKS))
> + if (si->orig_video_isVGA != VIDEO_TYPE_EFI ||
> + !(si->capabilities & VIDEO_CAPABILITY_SKIP_QUIRKS))
> dmi_check_system(efifb_dmi_system_table);
>
> - if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI &&
> + if (si->orig_video_isVGA == VIDEO_TYPE_EFI &&
> dmi_check_system(efifb_dmi_swap_width_height)) {
> - u16 temp = screen_info.lfb_width;
> + u16 temp = si->lfb_width;
>
> - screen_info.lfb_width = screen_info.lfb_height;
> - screen_info.lfb_height = temp;
> - screen_info.lfb_linelength = 4 * screen_info.lfb_width;
> + si->lfb_width = si->lfb_height;
> + si->lfb_height = temp;
> + si->lfb_linelength = 4 * si->lfb_width;
> }
> }
>
> -__init void sysfb_set_efifb_fwnode(struct platform_device *pd)
> +__init void sysfb_set_efifb_fwnode(const struct screen_info *si, struct platform_device *pd)
> {
> - if (screen_info.orig_video_isVGA == VIDEO_TYPE_EFI && IS_ENABLED(CONFIG_PCI)) {
> + if (si->orig_video_isVGA == VIDEO_TYPE_EFI && IS_ENABLED(CONFIG_PCI)) {
> fwnode_init(&efifb_fwnode, &efifb_fwnode_ops);
> pd->dev.fwnode = &efifb_fwnode;
> }
> diff --git a/drivers/firmware/sysfb.c b/drivers/firmware/sysfb.c
> index 889e5b05c739..916b28538a29 100644
> --- a/drivers/firmware/sysfb.c
> +++ b/drivers/firmware/sysfb.c
> @@ -155,7 +155,7 @@ static __init int sysfb_init(void)
> if (disabled)
> goto unlock_mutex;
>
> - sysfb_apply_efi_quirks();
> + sysfb_apply_efi_quirks(si);
>
> parent = sysfb_parent_dev(si);
> if (IS_ERR(parent)) {
> @@ -200,7 +200,7 @@ static __init int sysfb_init(void)
>
> pd->dev.parent = parent;
>
> - sysfb_set_efifb_fwnode(pd);
> + sysfb_set_efifb_fwnode(si, pd);
>
> ret = platform_device_add_data(pd, si, sizeof(*si));
> if (ret)
> diff --git a/drivers/firmware/sysfb_simplefb.c b/drivers/firmware/sysfb_simplefb.c
> index 592d8a644619..71f542e37732 100644
> --- a/drivers/firmware/sysfb_simplefb.c
> +++ b/drivers/firmware/sysfb_simplefb.c
> @@ -117,7 +117,7 @@ __init struct platform_device *sysfb_create_simplefb(const struct screen_info *s
>
> pd->dev.parent = parent;
>
> - sysfb_set_efifb_fwnode(pd);
> + sysfb_set_efifb_fwnode(si, pd);
>
> ret = platform_device_add_resources(pd, &res, 1);
> if (ret)
> diff --git a/include/linux/sysfb.h b/include/linux/sysfb.h
> index b449665c686a..8527a50a5290 100644
> --- a/include/linux/sysfb.h
> +++ b/include/linux/sysfb.h
> @@ -82,16 +82,17 @@ static inline bool sysfb_handles_screen_info(void)
> #ifdef CONFIG_EFI
>
> extern struct efifb_dmi_info efifb_dmi_list[];
> -void sysfb_apply_efi_quirks(void);
> -void sysfb_set_efifb_fwnode(struct platform_device *pd);
> +void sysfb_apply_efi_quirks(struct screen_info *si);
> +void sysfb_set_efifb_fwnode(const struct screen_info *si, struct platform_device *pd);
>
> #else /* CONFIG_EFI */
>
> -static inline void sysfb_apply_efi_quirks(void)
> +static inline void sysfb_apply_efi_quirks(struct screen_info *si)
> {
> }
>
> -static inline void sysfb_set_efifb_fwnode(struct platform_device *pd)
> +static inline void sysfb_set_efifb_fwnode(const struct screen_info *si,
> + struct platform_device *pd)
> {
> }
>
> --
> 2.51.1
>
>
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