[PATCH] ARM: rpi: parse memory from vc fdt

[PATCH] ARM: rpi: parse memory from vc fdt

[Marcin Niestroj]

From: Marcin Niestroj <m.niestroj@emb.dev>

Currently for RaspberryPi platform there is only one memory bank
created, based on information fetched over mailbox. This is fine for
booting Barebox, but unfortunately all the other memory banks are not
propagated to Linux during boot, thus cannot be utilized. In fact, even
when using /vc.dtb as device-tree for Linux, all memory nodes in FDT are
deleted and new ones are created by Barebox by memory fixup mechanism,
using exising RAM information. As a result RaspberryPi 4 boots Linux
with 1GB RAM available, instead of 2GB (2 banks, each 1GB).

At the end of VideoCore FDT parsing, do the same as of_probe_memory() in
mem_initcall does, but for VideoCore provided devicetree/memory
information. During Linux boot this information is used for memory fixup
mechanism and in case of RaspberryPi 4 this results in 2 memory banks
being propagated:

  # ls /proc/device-tree/memory*
  /proc/device-tree/memory@0:
  device_type  name         reg

  /proc/device-tree/memory@40000000:
  device_type  name         reg

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>
---
 arch/arm/boards/raspberry-pi/rpi-common.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boards/raspberry-pi/rpi-common.c b/arch/arm/boards/raspberry-pi/rpi-common.c
index 77935e5c88..0855eee872 100644
--- a/arch/arm/boards/raspberry-pi/rpi-common.c
+++ b/arch/arm/boards/raspberry-pi/rpi-common.c
@@ -258,7 +258,7 @@ static u32 rpi_boot_mode, rpi_boot_part;
 static void rpi_vc_fdt_parse(void *fdt)
 {
 	int ret;
-	struct device_node *root, *chosen, *bootloader;
+	struct device_node *root, *chosen, *bootloader, *memory;
 	char *str;
 
 	root = of_unflatten_dtb(fdt, INT_MAX);
@@ -324,6 +324,20 @@ static void rpi_vc_fdt_parse(void *fdt)
 	if (IS_ENABLED(CONFIG_RESET_SOURCE))
 		reset_source_set(rpi_decode_pm_rsts(chosen, bootloader));
 
+	/* Parse all available nodes with "memory" device_type */
+	memory = root;
+	while (1) {
+		int err;
+
+		memory = of_find_node_by_type(memory, "memory");
+		if (!memory)
+			break;
+
+		err = of_add_memory(memory, false);
+		if (err)
+			ret = err;
+	}
+
 out:
 	if (root)
 		of_delete_node(root);
-- 
2.39.0

Re: [PATCH] ARM: rpi: parse memory from vc fdt

[Ahmad Fatoum]

On 10.01.23 20:32, Marcin Niestroj wrote:
> From: Marcin Niestroj <m.niestroj@emb.dev>
> 
> Currently for RaspberryPi platform there is only one memory bank
> created, based on information fetched over mailbox. This is fine for
> booting Barebox, but unfortunately all the other memory banks are not
> propagated to Linux during boot, thus cannot be utilized. In fact, even
> when using /vc.dtb as device-tree for Linux, all memory nodes in FDT are
> deleted and new ones are created by Barebox by memory fixup mechanism,
> using exising RAM information. As a result RaspberryPi 4 boots Linux
> with 1GB RAM available, instead of 2GB (2 banks, each 1GB).
> 
> At the end of VideoCore FDT parsing, do the same as of_probe_memory() in
> mem_initcall does, but for VideoCore provided devicetree/memory
> information. During Linux boot this information is used for memory fixup
> mechanism and in case of RaspberryPi 4 this results in 2 memory banks
> being propagated:
> 
>   # ls /proc/device-tree/memory*
>   /proc/device-tree/memory@0:
>   device_type  name         reg
> 
>   /proc/device-tree/memory@40000000:
>   device_type  name         reg
> 
> Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>

Thanks for your patch. I suggest this be applied to master.

I think it may be worthwhile in future to only query the mailbox
interface for memory in PBL (lowlevel.c) for use as early mem and
depend solely on DT in barebox proper.

> ---
>  arch/arm/boards/raspberry-pi/rpi-common.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)

> +		err = of_add_memory(memory, false);
> +		if (err)
> +			ret = err;

No one does anything wither either err or ret, so you can drop that.
Anyways:

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> +	}
> +
>  out:
>  	if (root)
>  		of_delete_node(root);

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
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Re: [PATCH] ARM: rpi: parse memory from vc fdt

[Sascha Hauer]

On Tue, Jan 10, 2023 at 08:56:13PM +0100, Ahmad Fatoum wrote:
> On 10.01.23 20:32, Marcin Niestroj wrote:
> > From: Marcin Niestroj <m.niestroj@emb.dev>
> > 
> > Currently for RaspberryPi platform there is only one memory bank
> > created, based on information fetched over mailbox. This is fine for
> > booting Barebox, but unfortunately all the other memory banks are not
> > propagated to Linux during boot, thus cannot be utilized. In fact, even
> > when using /vc.dtb as device-tree for Linux, all memory nodes in FDT are
> > deleted and new ones are created by Barebox by memory fixup mechanism,
> > using exising RAM information. As a result RaspberryPi 4 boots Linux
> > with 1GB RAM available, instead of 2GB (2 banks, each 1GB).
> > 
> > At the end of VideoCore FDT parsing, do the same as of_probe_memory() in
> > mem_initcall does, but for VideoCore provided devicetree/memory
> > information. During Linux boot this information is used for memory fixup
> > mechanism and in case of RaspberryPi 4 this results in 2 memory banks
> > being propagated:
> > 
> >   # ls /proc/device-tree/memory*
> >   /proc/device-tree/memory@0:
> >   device_type  name         reg
> > 
> >   /proc/device-tree/memory@40000000:
> >   device_type  name         reg
> > 
> > Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>
> 
> Thanks for your patch. I suggest this be applied to master.
> 
> I think it may be worthwhile in future to only query the mailbox
> interface for memory in PBL (lowlevel.c) for use as early mem and
> depend solely on DT in barebox proper.
> 
> > ---
> >  arch/arm/boards/raspberry-pi/rpi-common.c | 16 +++++++++++++++-
> >  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> > +		err = of_add_memory(memory, false);
> > +		if (err)
> > +			ret = err;
> 
> No one does anything wither either err or ret, so you can drop that.

Did that and applied to master.

Sascha

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |