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SubjectRe: [PATCH] powerpc/legacy_serial: Use early_ioremap()
Date
Hi Christophe,

On Wed, 2020-02-05 at 12:03 +0000, Christophe Leroy wrote:
> [ 0.000000] ioremap() called early from
> find_legacy_serial_ports+0x3cc/0x474. Use early_ioremap() instead
>

I was just about to dig into this error message and found you patch. I
applied it to a v5.5 base.

> find_legacy_serial_ports() is called early from setup_arch(), before
> paging_init(). vmalloc is not available yet, ioremap shouldn't be
> used that early.
>
> Use early_ioremap() and switch to a regular ioremap() later.
>
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>

On my system (Freescale T2080 SOC) this seems to cause a crash/hang in
early boot. Unfortunately because this is affecting the boot console I
don't get any earlyprintk output.

> ---
> arch/powerpc/kernel/legacy_serial.c | 33 +++++++++++++++++++++++++
> ----
> 1 file changed, 29 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/legacy_serial.c
> b/arch/powerpc/kernel/legacy_serial.c
> index f061e06e9f51..8b2c1a8553a0 100644
> --- a/arch/powerpc/kernel/legacy_serial.c
> +++ b/arch/powerpc/kernel/legacy_serial.c
> @@ -15,6 +15,7 @@
> #include <asm/udbg.h>
> #include <asm/pci-bridge.h>
> #include <asm/ppc-pci.h>
> +#include <asm/early_ioremap.h>
>
> #undef DEBUG
>
> @@ -34,6 +35,7 @@ static struct legacy_serial_info {
> unsigned int clock;
> int irq_check_parent;
> phys_addr_t taddr;
> + void __iomem *early_addr;
> } legacy_serial_infos[MAX_LEGACY_SERIAL_PORTS];
>
> static const struct of_device_id legacy_serial_parents[] __initconst
> = {
> @@ -325,17 +327,16 @@ static void __init
> setup_legacy_serial_console(int console)
> {
> struct legacy_serial_info *info =
> &legacy_serial_infos[console];
> struct plat_serial8250_port *port =
> &legacy_serial_ports[console];
> - void __iomem *addr;
> unsigned int stride;
>
> stride = 1 << port->regshift;
>
> /* Check if a translated MMIO address has been found */
> if (info->taddr) {
> - addr = ioremap(info->taddr, 0x1000);
> - if (addr == NULL)
> + info->early_addr = early_ioremap(info->taddr, 0x1000);
> + if (info->early_addr == NULL)
> return;
> - udbg_uart_init_mmio(addr, stride);
> + udbg_uart_init_mmio(info->early_addr, stride);
> } else {
> /* Check if it's PIO and we support untranslated PIO */
> if (port->iotype == UPIO_PORT && isa_io_special)
> @@ -353,6 +354,30 @@ static void __init
> setup_legacy_serial_console(int console)
> udbg_uart_setup(info->speed, info->clock);
> }
>
> +static int __init ioremap_legacy_serial_console(void)
> +{
> + struct legacy_serial_info *info =
> &legacy_serial_infos[legacy_serial_console];
> + struct plat_serial8250_port *port =
> &legacy_serial_ports[legacy_serial_console];
> + void __iomem *vaddr;
> +
> + if (legacy_serial_console < 0)
> + return 0;
> +
> + if (!info->early_addr)
> + return 0;
> +
> + vaddr = ioremap(info->taddr, 0x1000);
> + if (WARN_ON(!vaddr))
> + return -ENOMEM;
> +
> + udbg_uart_init_mmio(vaddr, 1 << port->regshift);
> + early_iounmap(info->early_addr, 0x1000);
> + info->early_addr = NULL;
> +
> + return 0;
> +}
> +early_initcall(ioremap_legacy_serial_console);
> +
> /*
> * This is called very early, as part of setup_system() or
> eventually
> * setup_arch(), basically before anything else in this file. This
> function
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