Re: [Regression 5.6-rc1][Bisected b6231ea2b3c6] Powerpc 8xx doesn't boot anymore

On 02/12/2020 02:24 PM, Christophe Leroy wrote:

Hi Rasmus,

Kernel 5.6-rc1 silently fails on boot.

I bisected the problem to commit b6231ea2b3c6 ("soc: fsl: qe: drop 
broken lazy call of cpm_muram_init()")

I get a bad_page_fault() for an access at address 8 in 
cpm_muram_alloc_common(), called from cpm_uart_console_setup() via 
cpm_uart_allocbuf()

Reverting the guilty commit on top of 5.6-rc1 is not trivial.

In your commit text you explain that cpm_muram_init() is called via 
subsys_initcall. But console init is done before that, so it cannot work.

Do you have a fix for that ?

The following patch allows powerpc 8xx to boot again. Don't know if 
that's the good place and way to do the fix though.

---

diff --git a/drivers/tty/serial/cpm_uart/cpm_uart_core.c 

b/drivers/tty/serial/cpm_uart/cpm_uart_core.c
index 4cabded8390b..341d682ec6eb 100644

--- a/drivers/tty/serial/cpm_uart/cpm_uart_core.c
+++ b/drivers/tty/serial/cpm_uart/cpm_uart_core.c

@@ -1351,6 +1351,7 @@ static int __init cpm_uart_console_setup(struct 

console *co, char *options)
  		clrbits32(&pinfo->sccp->scc_gsmrl, SCC_GSMRL_ENR | SCC_GSMRL_ENT);
  	}

+	cpm_muram_init();
  	ret = cpm_uart_allocbuf(pinfo, 1);

  	if (ret)

---
Christophe

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