linux-kernel - Re: [PATCH] memory: omap-gpmc: Don't try to save the GPMC context

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Date:	Fri, 7 Aug 2015 12:10:57 +0300
From:	Roger Quadros <rogerq@...com>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>,
	<linux-kernel@...r.kernel.org>, Tony Lindgren <tony@...mide.com>
CC:	Javier Martinez Canillas <javier@...hile0.org>,
	<linux-omap@...r.kernel.org>
Subject: Re: [PATCH] memory: omap-gpmc: Don't try to save the GPMC context

On 05/08/15 15:24, Tomeu Vizoso wrote:
> ...if there isn't one already.
> 
> If for some reason the GPMC device hasn't been probed yet, gpmc_base is
> going to be NULL. Because there's no context yet to be saved, just turn
> these functions into no-ops until that device gets probed.
> 
> Unable to handle kernel NULL pointer dereference at virtual address 00000010
> pgd = c0204000
> [00000010] *pgd=00000000
> Internal error: Oops: 5 [#1] SMP ARM
> Modules linked in:
> CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc5-next-20150804-05947-g23f38fe8eda9 #1
> Hardware name: Generic OMAP3-GP (Flattened Device Tree)
> task: c0e623e8 ti: c0e5c000 task.ti: c0e5c000
> PC is at omap3_gpmc_save_context+0x8/0xc4
> LR is at omap_sram_idle+0x154/0x23c
> pc : [<c087c7ac>]    lr : [<c023262c>]    psr: 60000193
> sp : c0e5df40  ip : c0f92a80  fp : c0999eb0
> r10: c0e57364  r9 : c0e66f14  r8 : 00000003
> r7 : 00000000  r6 : 00000003  r5 : 00000000  r4 : c0f5f174
> r3 : c0fa4fe8  r2 : 00000000  r1 : 00000000  r0 : fa200280
> Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
> Control: 10c5387d  Table: 80204019  DAC: 00000015
> Process swapper/0 (pid: 0, stack limit = 0xc0e5c220)
> Stack: (0xc0e5df40 to 0xc0e5e000)
> df40: 00000000 c0e66ef8 c0f5f1a4 00000000 00000003 c02333a4 c3813822 00000000
> df60: 00000000 c0e5a5c8 cfb8a5d0 c07f0c44 0e4f1d7e 00000000 00000000 00000000
> df80: c3813822 00000000 cfb8a5d0 c0e5e4e4 cfb8a5d0 c0e66f14 c0e5a5c8 c0e5e54c
> dfa0: c0e5e544 c0e57364 c0999eb0 c0277758 000000fa c0f5d000 00000000 c0d61c18
> dfc0: ffffffff ffffffff 00000000 c0d61674 00000000 c0df7a48 00000000 c0f5d5d4
> dfe0: c0e5e4c0 c0df7a44 c0e634f8 80204059 00000000 8020807c 00000000 00000000
> [<c087c7ac>] (omap3_gpmc_save_context) from [<c023262c>] (omap_sram_idle+0x154/0x23c)
> [<c023262c>] (omap_sram_idle) from [<c02333a4>] (omap3_enter_idle_bm+0xec/0x1a8)
> [<c02333a4>] (omap3_enter_idle_bm) from [<c07f0c44>] (cpuidle_enter_state+0xbc/0x284)
> [<c07f0c44>] (cpuidle_enter_state) from [<c0277758>] (cpu_startup_entry+0x174/0x24c)
> [<c0277758>] (cpu_startup_entry) from [<c0d61c18>] (start_kernel+0x358/0x3c0)
> [<c0d61c18>] (start_kernel) from [<8020807c>] (0x8020807c)
> Code: c0ccace8 c0ccacc0 e59f30b4 e5932000 (e5921010)
> 
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
> Suggested-by: Javier Martinez Canillas <javier@...hile0.org>

Acked-by: Roger Quadros <rogerq@...com>

cheers,
-roger

> ---
>  drivers/memory/omap-gpmc.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/memory/omap-gpmc.c b/drivers/memory/omap-gpmc.c
> index 3a27a84ad3ec..9426276dbe14 100644
> --- a/drivers/memory/omap-gpmc.c
> +++ b/drivers/memory/omap-gpmc.c
> @@ -2245,6 +2245,9 @@ void omap3_gpmc_save_context(void)
>  {
>  	int i;
>  
> +	if (!gpmc_base)
> +		return;
> +
>  	gpmc_context.sysconfig = gpmc_read_reg(GPMC_SYSCONFIG);
>  	gpmc_context.irqenable = gpmc_read_reg(GPMC_IRQENABLE);
>  	gpmc_context.timeout_ctrl = gpmc_read_reg(GPMC_TIMEOUT_CONTROL);
> @@ -2277,6 +2280,9 @@ void omap3_gpmc_restore_context(void)
>  {
>  	int i;
>  
> +	if (!gpmc_base)
> +		return;
> +
>  	gpmc_write_reg(GPMC_SYSCONFIG, gpmc_context.sysconfig);
>  	gpmc_write_reg(GPMC_IRQENABLE, gpmc_context.irqenable);
>  	gpmc_write_reg(GPMC_TIMEOUT_CONTROL, gpmc_context.timeout_ctrl);
> 
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