[PATCH v4 0/8] Move framebuffer reservation for SPL to RAM end
Move video memory reservation for SPL at end of RAM so that it does not interefere with reservations for next stage so that the next stage need not have holes in between for passed regions and instead it can maintain continuity in reservations.
Also catch the bloblist before starting reservations to avoid the same problem.
While at it, also fill missing fields in video handoff struct before passing it to next stage.
This is as per discussions at : For moving SPL framebuffer reservation at end of RAM:
https://lore.kernel.org/all/CAPnjgZ3xSoe_G3yrqwuAvoiVjUfZ+YQgkOR0ZTVXGT9VK8T...
For filling missing video handoff fields : https://lore.kernel.org/all/CAPnjgZ1Hs0rNf0JDirp6YPsOQ5=QqQSP9g9qRwLoOASUV8a...
Changelog: V2: - Make a generic function to reserve video memory at SPL stage. - Add debug prints while skipping framebuffer allocation at uboot. - Correct commenting style as suggested.
V3: - Change spl_reserve_video to spl_reserve_video_from_ram_top which enforce framebuffer reservation from end of RAM. - Use gd->ram_top instead of local ram_top and update gd->reloc_addr after each reservation. - Print error message on framebuffer reservation. - Update SPL doc with spl splash screen specific info.
V4: - Split patches into atomic commits. - Remove duplicate check for video blob passed addresses and error out if invalid address/size received from blob. - Improve SPL documentation memory reservation scheme and print message for video memory reservation from bloblist. - Add Reviewed-By.
Test logs: https://gist.github.com/devarsht/6a748b1d69bd2a4b60695a5e7776db73
Devarsh Thakkar (8): spl: Enforce framebuffer reservation from end of RAM arm: mach-k3: common: Reserve video memory from end of the RAM board: ti: am62x: evm: Remove video_setup from spl_board_init common/board_f: Catch bloblist before starting resevations video: Skip framebuffer reservation if already reserved video: Fill video handoff in video post probe doc: spl: Add info for missing Kconfigs doc: spl: Add info regarding memory reservation
arch/arm/mach-k3/common.c | 17 ++++++++++----- board/ti/am62x/evm.c | 18 ---------------- common/board_f.c | 41 +++++++++++++++++++++++++++++++----- common/spl/spl.c | 19 +++++++++++++++++ doc/develop/spl.rst | 37 ++++++++++++++++++++++++++++++++ drivers/video/video-uclass.c | 39 +++++++++++++++++++++++----------- include/spl.h | 10 +++++++++ 7 files changed, 141 insertions(+), 40 deletions(-)
Add an API which enforces framebuffer reservation from end of RAM. This is done so that next stage can directly skip this region before carrying out further reservations.
Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V2: No change.
V3: Change spl_reserve_video to spl_reserve_video_from_ram_top which enforce framebuffer reservation from end of RAM.
V4: Split this to an independent patch with more details added in comments for API in header file. --- common/spl/spl.c | 19 +++++++++++++++++++ include/spl.h | 10 ++++++++++ 2 files changed, 29 insertions(+)
diff --git a/common/spl/spl.c b/common/spl/spl.c index 3ce5bfeec8..b65c439e7a 100644 --- a/common/spl/spl.c +++ b/common/spl/spl.c @@ -42,6 +42,7 @@ #include <fdt_support.h> #include <bootcount.h> #include <wdt.h> +#include <video.h>
DECLARE_GLOBAL_DATA_PTR; DECLARE_BINMAN_MAGIC_SYM; @@ -152,6 +153,24 @@ void spl_fixup_fdt(void *fdt_blob) #endif }
+int spl_reserve_video_from_ram_top(void) +{ + if (CONFIG_IS_ENABLED(VIDEO)) { + ulong addr; + int ret; + + addr = gd->ram_top; + ret = video_reserve(&addr); + if (ret) + return ret; + debug("Reserving %luk for video at: %08lx\n", + ((unsigned long)gd->relocaddr - addr) >> 10, addr); + gd->relocaddr = addr; + } + + return 0; +} + ulong spl_get_image_pos(void) { if (!CONFIG_IS_ENABLED(BINMAN_UBOOT_SYMBOLS)) diff --git a/include/spl.h b/include/spl.h index 0952188901..043875f10f 100644 --- a/include/spl.h +++ b/include/spl.h @@ -889,6 +889,16 @@ int spl_usb_load(struct spl_image_info *spl_image,
int spl_ymodem_load_image(struct spl_image_info *spl_image, struct spl_boot_device *bootdev); +/** + * spl_reserve_video_from_ram_top() - Reserve framebuffer memory from end of RAM + * + * This enforces framebuffer reservation at SPL stage from end of RAM so that + * next stage can directly skip this pre-reserved area before carrying out + * further reservations. The allocation address is stored in struct video_uc_plat. + * + * Return: 0 on success, otherwise error code + */ +int spl_reserve_video_from_ram_top(void);
/** * spl_invoke_atf - boot using an ARM trusted firmware image
On Sat, 25 Nov 2023 at 09:27, Devarsh Thakkar devarsht@ti.com wrote:
Add an API which enforces framebuffer reservation from end of RAM. This is done so that next stage can directly skip this region before carrying out further reservations.
Signed-off-by: Devarsh Thakkar devarsht@ti.com
V2: No change.
V3: Change spl_reserve_video to spl_reserve_video_from_ram_top which enforce framebuffer reservation from end of RAM.
V4: Split this to an independent patch with more details added in comments for API in header file.
common/spl/spl.c | 19 +++++++++++++++++++ include/spl.h | 10 ++++++++++
Reviewed-by: Simon Glass sjg@chromium.org
Setup video memory before page table reservation using "spl_reserve_video_from_ram_top" which ensures framebuffer memory gets reserved from the end of RAM.
This is done to enable the next stage to directly skip the pre-reserved area from previous stage right from the end of RAM without having to make any gaps/holes to accommodate those regions which was the case before as previous stage reserved region not from the end of RAM.
Use gd->ram_top instead of local ram_top and update gd->reloc_addr after each reservation to ensure further regions are reserved properly.
Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V2: - Make a generic function "spl_reserve_video" under common/spl which can be re-used by other platforms too for reserving video memory from spl.
V3: - Change spl_reserve_video to spl_reserve_video_from_ram_top which enforce framebuffer reservation from end of RAM - Use gd->ram_top instead of local ram_top and update gd->reloc_addr after each reservation - Print error message on framebuffer reservation
V4: - Split this into a separate patch --- arch/arm/mach-k3/common.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c index fd400e7e3d..42ceeb5296 100644 --- a/arch/arm/mach-k3/common.c +++ b/arch/arm/mach-k3/common.c @@ -524,19 +524,26 @@ void remove_fwl_configs(struct fwl_data *fwl_data, size_t fwl_data_size) void spl_enable_cache(void) { #if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF)) - phys_addr_t ram_top = CFG_SYS_SDRAM_BASE; + gd->ram_top = CFG_SYS_SDRAM_BASE; + int ret = 0;
dram_init();
/* reserve TLB table */ gd->arch.tlb_size = PGTABLE_SIZE;
- ram_top += get_effective_memsize(); + gd->ram_top += get_effective_memsize(); /* keep ram_top in the 32-bit address space */ - if (ram_top >= 0x100000000) - ram_top = (phys_addr_t) 0x100000000; + if (gd->ram_top >= 0x100000000) + gd->ram_top = (phys_addr_t)0x100000000;
- gd->arch.tlb_addr = ram_top - gd->arch.tlb_size; + gd->relocaddr = gd->ram_top; + + ret = spl_reserve_video_from_ram_top(); + if (ret) + panic("Failed to reserve framebuffer memory (%d)\n", ret); + + gd->arch.tlb_addr = gd->relocaddr - gd->arch.tlb_size; gd->arch.tlb_addr &= ~(0x10000 - 1); debug("TLB table from %08lx to %08lx\n", gd->arch.tlb_addr, gd->arch.tlb_addr + gd->arch.tlb_size);
Hi Devarsh,
On 25/11/23 21:56, Devarsh Thakkar wrote:
Setup video memory before page table reservation using "spl_reserve_video_from_ram_top" which ensures framebuffer memory gets reserved from the end of RAM.
This is done to enable the next stage to directly skip the pre-reserved area from previous stage right from the end of RAM without having to make any gaps/holes to accommodate those regions which was the case before as previous stage reserved region not from the end of RAM.
Use gd->ram_top instead of local ram_top and update gd->reloc_addr after each reservation to ensure further regions are reserved properly.
Signed-off-by: Devarsh Thakkar devarsht@ti.com
Reviewed-by: Nikhil M Jain n-jain1@ti.com
Regards, Nikhil
V2:
- Make a generic function "spl_reserve_video" under common/spl which can be re-used by other platforms too for reserving video memory from spl.
V3:
- Change spl_reserve_video to spl_reserve_video_from_ram_top which enforce framebuffer reservation from end of RAM
- Use gd->ram_top instead of local ram_top and update gd->reloc_addr after each reservation
- Print error message on framebuffer reservation
V4:
- Split this into a separate patch
arch/arm/mach-k3/common.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/arm/mach-k3/common.c b/arch/arm/mach-k3/common.c index fd400e7e3d..42ceeb5296 100644 --- a/arch/arm/mach-k3/common.c +++ b/arch/arm/mach-k3/common.c @@ -524,19 +524,26 @@ void remove_fwl_configs(struct fwl_data *fwl_data, size_t fwl_data_size) void spl_enable_cache(void) { #if !(defined(CONFIG_SYS_ICACHE_OFF) && defined(CONFIG_SYS_DCACHE_OFF))
- phys_addr_t ram_top = CFG_SYS_SDRAM_BASE;
gd->ram_top = CFG_SYS_SDRAM_BASE;
int ret = 0;
dram_init();
/* reserve TLB table */ gd->arch.tlb_size = PGTABLE_SIZE;
- ram_top += get_effective_memsize();
- gd->ram_top += get_effective_memsize(); /* keep ram_top in the 32-bit address space */
- if (ram_top >= 0x100000000)
ram_top = (phys_addr_t) 0x100000000;
- if (gd->ram_top >= 0x100000000)
gd->ram_top = (phys_addr_t)0x100000000;
- gd->arch.tlb_addr = ram_top - gd->arch.tlb_size;
- gd->relocaddr = gd->ram_top;
- ret = spl_reserve_video_from_ram_top();
- if (ret)
panic("Failed to reserve framebuffer memory (%d)\n", ret);- gd->arch.tlb_addr = gd->relocaddr - gd->arch.tlb_size; gd->arch.tlb_addr &= ~(0x10000 - 1); debug("TLB table from %08lx to %08lx\n", gd->arch.tlb_addr, gd->arch.tlb_addr + gd->arch.tlb_size);
Remove video_setup from evm_init sequence since video memory is getting called at an earlier place to make sure video memory is reserved at the end of RAM.
Suggested-by: Simon Glass sjg@chromium.org Signed-off-by: Devarsh Thakkar devarsht@ti.com Reviewed-by: Simon Glass sjg@chromium.org --- V2: No change V3: No change V4: Add Reviewed-by --- board/ti/am62x/evm.c | 18 ------------------ 1 file changed, 18 deletions(-)
diff --git a/board/ti/am62x/evm.c b/board/ti/am62x/evm.c index ad93908840..88e02155ee 100644 --- a/board/ti/am62x/evm.c +++ b/board/ti/am62x/evm.c @@ -60,27 +60,9 @@ int dram_init_banksize(void) }
#if defined(CONFIG_SPL_BUILD) -static int video_setup(void) -{ - if (CONFIG_IS_ENABLED(VIDEO)) { - ulong addr; - int ret; - - addr = gd->relocaddr; - ret = video_reserve(&addr); - if (ret) - return ret; - debug("Reserving %luk for video at: %08lx\n", - ((unsigned long)gd->relocaddr - addr) >> 10, addr); - gd->relocaddr = addr; - } - - return 0; -}
void spl_board_init(void) { - video_setup(); enable_caches(); if (IS_ENABLED(CONFIG_SPL_SPLASH_SCREEN) && IS_ENABLED(CONFIG_SPL_BMP)) splash_display();
Start reservations needed for init sequence only after catching bloblists from previous stage.
This is to avoid catching bloblists in the middle causing gaps while u-boot is reserving.
Adjust the relocaddr as per video hand-off information received from previous stage so that further reservations start only after regions reserved for previous stages
Skip reservation for video memory if it was already filled by a bloblist.
Signed-off-by: Devarsh Thakkar devarsht@ti.com Reviewed-by: Simon Glass sjg@chromium.org --- V2: Fix typo in commit title and checkpatch warnings/checks V3: No change V4: Add Reviewed-by --- common/board_f.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-)
diff --git a/common/board_f.c b/common/board_f.c index d4d7d01f8f..acf802c9cb 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -403,7 +403,7 @@ __weak int arch_reserve_mmu(void) return 0; }
-static int reserve_video(void) +static int reserve_video_from_videoblob(void) { if (IS_ENABLED(CONFIG_SPL_VIDEO_HANDOFF) && spl_phase() > PHASE_SPL) { struct video_handoff *ho; @@ -412,8 +412,34 @@ static int reserve_video(void) if (!ho) return log_msg_ret("blf", -ENOENT); video_reserve_from_bloblist(ho); - gd->relocaddr = ho->fb; - } else if (CONFIG_IS_ENABLED(VIDEO)) { + + /* Sanity check fb from blob is before current relocaddr */ + if (likely(gd->relocaddr > (unsigned long)ho->fb)) + gd->relocaddr = ho->fb; + } + + return 0; +} + +/* + * Check if any bloblist received specifying reserved areas from previous stage and adjust + * gd->relocaddr accordingly, so that we start reserving after pre-reserved areas + * from previous stage. + * + * NOTE: + * IT is recommended that all bloblists from previous stage are reserved from ram_top + * as next stage will simply start reserving further regions after them. + */ +static int setup_relocaddr_from_bloblist(void) +{ + reserve_video_from_videoblob(); + + return 0; +} + +static int reserve_video(void) +{ + if (CONFIG_IS_ENABLED(VIDEO)) { ulong addr; int ret;
@@ -923,6 +949,7 @@ static const init_fnc_t init_sequence_f[] = { reserve_pram, #endif reserve_round_4k, + setup_relocaddr_from_bloblist, arch_reserve_mmu, reserve_video, reserve_trace,
Skip framebufer reservation if it was already reserved from previous stage and whose information was passed using a bloblist.
Return error in case framebuffer information received from bloblist is invalid i.e NULL or empty.
While at it, improve the debug message to make it more clear that address in discussion is of framebuffer and not bloblist and also match it with printing scheme followed in video_reserve function.
Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V2: - Add debug prints - Fix commenting style V3: - Fix commenting style V4: - Remove extra checks on gd for video data in video_reserve - Add check and return error if video handoff provided info is invalid - Improve debug message - Remove Reviewed-by due to additional changes per review comments --- common/board_f.c | 8 ++++++-- drivers/video/video-uclass.c | 10 ++++++++-- 2 files changed, 14 insertions(+), 4 deletions(-)
diff --git a/common/board_f.c b/common/board_f.c index acf802c9cb..442b8349d0 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -407,11 +407,15 @@ static int reserve_video_from_videoblob(void) { if (IS_ENABLED(CONFIG_SPL_VIDEO_HANDOFF) && spl_phase() > PHASE_SPL) { struct video_handoff *ho; + int ret = 0;
ho = bloblist_find(BLOBLISTT_U_BOOT_VIDEO, sizeof(*ho)); if (!ho) - return log_msg_ret("blf", -ENOENT); - video_reserve_from_bloblist(ho); + return log_msg_ret("Missing video bloblist", -ENOENT); + + ret = video_reserve_from_bloblist(ho); + if (ret) + return log_msg_ret("Invalid Video handoff info", ret);
/* Sanity check fb from blob is before current relocaddr */ if (likely(gd->relocaddr > (unsigned long)ho->fb)) diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c index f743ed74c8..378f01f3d7 100644 --- a/drivers/video/video-uclass.c +++ b/drivers/video/video-uclass.c @@ -123,6 +123,9 @@ int video_reserve(ulong *addrp) struct udevice *dev; ulong size;
+ if (IS_ENABLED(CONFIG_SPL_VIDEO_HANDOFF) && spl_phase() > PHASE_SPL) + return 0; + gd->video_top = *addrp; for (uclass_find_first_device(UCLASS_VIDEO, &dev); dev; @@ -208,11 +211,14 @@ int video_fill_part(struct udevice *dev, int xstart, int ystart, int xend,
int video_reserve_from_bloblist(struct video_handoff *ho) { + if (!ho->fb || ho->size == 0) + return -ENOENT; + gd->video_bottom = ho->fb; gd->fb_base = ho->fb; gd->video_top = ho->fb + ho->size; - debug("Reserving %luk for video using blob at: %08x\n", - ((unsigned long)ho->size) >> 10, (u32)ho->fb); + debug("%s: Reserving %lx bytes at %08x as per bloblist received\n", + __func__, (unsigned long)ho->size, (u32)ho->fb);
return 0; }
On Sat, 25 Nov 2023 at 09:27, Devarsh Thakkar devarsht@ti.com wrote:
Skip framebufer reservation if it was already reserved from previous stage and whose information was passed using a bloblist.
Return error in case framebuffer information received from bloblist is invalid i.e NULL or empty.
While at it, improve the debug message to make it more clear that address in discussion is of framebuffer and not bloblist and also match it with printing scheme followed in video_reserve function.
Signed-off-by: Devarsh Thakkar devarsht@ti.com
V2:
- Add debug prints
- Fix commenting style
V3:
- Fix commenting style
V4:
- Remove extra checks on gd for video data in video_reserve
- Add check and return error if video handoff provided info is invalid
- Improve debug message
- Remove Reviewed-by due to additional changes per review comments
common/board_f.c | 8 ++++++-- drivers/video/video-uclass.c | 10 ++++++++-- 2 files changed, 14 insertions(+), 4 deletions(-)
Reviewed-by: Simon Glass sjg@chromium.org
with nit below
diff --git a/common/board_f.c b/common/board_f.c index acf802c9cb..442b8349d0 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -407,11 +407,15 @@ static int reserve_video_from_videoblob(void) { if (IS_ENABLED(CONFIG_SPL_VIDEO_HANDOFF) && spl_phase() > PHASE_SPL) {
This is board_f.c so the SPL phase will always be PHASE_BOARD_F so can you please drop that second condition? It will confuse people.
struct video_handoff *ho;
int ret = 0; ho = bloblist_find(BLOBLISTT_U_BOOT_VIDEO, sizeof(*ho)); if (!ho)
return log_msg_ret("blf", -ENOENT);video_reserve_from_bloblist(ho);
return log_msg_ret("Missing video bloblist", -ENOENT);ret = video_reserve_from_bloblist(ho);if (ret)return log_msg_ret("Invalid Video handoff info", ret); /* Sanity check fb from blob is before current relocaddr */ if (likely(gd->relocaddr > (unsigned long)ho->fb))
[..]
Regards, Simon
Fill video handoff fields in video_post_probe as at this point we have full framebuffer-related information.
Also fill all the fields available in video hand-off struct as those were missing earlier and U-boot framework expects them to be filled for some of the functionalities.
Reported-by: Simon Glass sjg@chromium.org Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V2: - No change
V3: - Fix commit message per review comment - Add a note explaining assumption of single framebuffer
V4: - Wrap message to 72 chars --- drivers/video/video-uclass.c | 29 +++++++++++++++++++---------- 1 file changed, 19 insertions(+), 10 deletions(-)
diff --git a/drivers/video/video-uclass.c b/drivers/video/video-uclass.c index 378f01f3d7..f4cebf3087 100644 --- a/drivers/video/video-uclass.c +++ b/drivers/video/video-uclass.c @@ -144,16 +144,6 @@ int video_reserve(ulong *addrp) debug("Video frame buffers from %lx to %lx\n", gd->video_bottom, gd->video_top);
- if (spl_phase() == PHASE_SPL && CONFIG_IS_ENABLED(VIDEO_HANDOFF)) { - struct video_handoff *ho; - - ho = bloblist_add(BLOBLISTT_U_BOOT_VIDEO, sizeof(*ho), 0); - if (!ho) - return log_msg_ret("blf", -ENOENT); - ho->fb = *addrp; - ho->size = size; - } - return 0; }
@@ -552,6 +542,25 @@ static int video_post_probe(struct udevice *dev)
priv->fb_size = priv->line_length * priv->ysize;
+ /* + * Set up video handoff fields for passing video blob to next stage + * NOTE: + * This assumes that reserved video memory only uses a single framebuffer + */ + if (spl_phase() == PHASE_SPL && CONFIG_IS_ENABLED(BLOBLIST)) { + struct video_handoff *ho; + + ho = bloblist_add(BLOBLISTT_U_BOOT_VIDEO, sizeof(*ho), 0); + if (!ho) + return log_msg_ret("blf", -ENOENT); + ho->fb = gd->video_bottom; + ho->size = gd->video_top - gd->video_bottom; + ho->xsize = priv->xsize; + ho->ysize = priv->ysize; + ho->line_length = priv->line_length; + ho->bpix = priv->bpix; + } + if (IS_ENABLED(CONFIG_VIDEO_COPY) && plat->copy_base) priv->copy_fb = map_sysmem(plat->copy_base, plat->size);
Add info regarding splash screen, video, bloblist and GPIO related Kconfigs which were missing in the documentation.
Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V2: No change V3: No change V4: Patch split from parent --- doc/develop/spl.rst | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index 76e87f07c7..814530d348 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -65,6 +65,15 @@ CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/raw/nand_spl_load.o) CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o) CONFIG_SPL_RAM_DEVICE (common/spl/spl.c) CONFIG_SPL_WATCHDOG (drivers/watchdog/libwatchdog.o) +CONFIG_SPL_SYSCON (drivers/core/syscon-uclass.o) +CONFIG_SPL_GZIP (lib/gzip.o) +CONFIG_SPL_VIDEO (drivers/video/video-uclass.o drivers/video/vidconsole-uclass.o) +CONFIG_SPL_SPLASH_SCREEN (common/splash.o) +CONFIG_SPL_SPLASH_SOURCE (common/splash_source.o) +CONFIG_SPL_GPIO (drivers/gpio) +CONFIG_SPL_DM_GPIO (drivers/gpio/gpio-uclass.o) +CONFIG_SPL_BMP (drivers/video/bmp.o) +CONFIG_SPL_BLOBLIST (common/bloblist.o)
Adding SPL-specific code ------------------------
On Sat, 25 Nov 2023 at 09:27, Devarsh Thakkar devarsht@ti.com wrote:
Add info regarding splash screen, video, bloblist and GPIO related Kconfigs which were missing in the documentation.
Signed-off-by: Devarsh Thakkar devarsht@ti.com
V2: No change V3: No change V4: Patch split from parent
doc/develop/spl.rst | 9 +++++++++ 1 file changed, 9 insertions(+)
Reviewed-by: Simon Glass sjg@chromium.org
Add details regarding scheme which need to be followed in SPL and further stages for those regions which need to be preserved across bootstages.
Signed-off-by: Devarsh Thakkar devarsht@ti.com --- V1->V3: No change.
V4: Split this to separate patch and add more details regarding memory reservation scheme that needs to be followed at SPL. --- doc/develop/spl.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index 814530d348..0a3e572310 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -173,3 +173,31 @@ cflow will spit out a number of warnings as it does not parse the config files and picks functions based on #ifdef. Parsing the '.i' files instead introduces another set of headaches. These warnings are not usually important to understanding the flow, however. + + +Reserving memory in SPL +----------------------- + +If memory needs to be reserved in RAM during SPL stage with the requirement that +the SPL reserved memory remains preserved across further boot stages too +then it needs to be reserved mandatorily starting from end of RAM. This is to +ensure that further stages can simply skip this region before carrying out +further reservations or updating the relocation address. + +Also out of these regions which are to be preserved across further stages of +boot, video framebuffer memory region must be reserved first starting from +end of RAM for which helper function spl_reserve_video_from_ram_top is provided +which makes sure that video memory is placed at top of reservation area with +further reservations below it. + +The corresponding information of reservation for those regions can be passed to +further boot stages using a bloblist. For e.g. the information for +framebuffer area reserved by SPL can be passed onto U-boot using +BLOBLISTT_U_BOOT_VIDEO. + +The further boot stages need to parse each of the bloblist passed from SPL stage +starting from video bloblist and skip this whole SPL reserved memory area from +end of RAM as per the bloblists received, before carrying out further +reservations or updating the relocation address. For e.g, U-boot proper uses +function "setup_relocaddr_from_bloblist" to parse the bloblists passed from +previous stage and skip the memory reserved from previous stage accordingly.
On Sat, 25 Nov 2023 at 09:27, Devarsh Thakkar devarsht@ti.com wrote:
Add details regarding scheme which need to be followed in SPL and further stages for those regions which need to be preserved across bootstages.
Signed-off-by: Devarsh Thakkar devarsht@ti.com
V1->V3: No change.
V4: Split this to separate patch and add more details regarding memory reservation scheme that needs to be followed at SPL.
doc/develop/spl.rst | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
Reviewed-by: Simon Glass sjg@chromium.org
participants (3)
-
Devarsh Thakkar -
Nikhil Jain -
Simon Glass