[alsa-devel] [PATCH] ASoC: fsl: imx-audmux: Check if we are running a dt kernel

[Fabio Estevam]

On Tue, Sep 3, 2013 at 2:52 PM, Fabio Estevam
<fabio.estevam at freescale.com> wrote:
> Booting a mx51babbage board with a non-dt kernel leads to the following crash:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000001c
> pgd = 80004000
> [0000001c] *pgd=00000000
> Internal error: Oops: 5 [#1] SMP ARM
> Modules linked in:
> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.11.0-next-20130903 #287
> task: 9f860000 ti: 9f862000 task.ti: 9f862000
> PC is at of_get_next_available_child+0x5c/0x68
> LR is at of_get_next_available_child+0x1c/0x68
> pc : [<8043ea58>]    lr : [<8043ea18>]    psr: 60000193
> sp : 9f863d58  ip : 00000000  fp : 9f863d74
> r10: 9f89a010  r9 : 9f862000  r8 : 807bb26c
> r7 : 80615d5c  r6 : 00000000  r5 : 60000113  r4 : 00000000
> r3 : 00000000  r2 : 808770a4  r1 : 00000011  r0 : 60000113
> Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
> Control: 10c5387d  Table: 90004019  DAC: 00000017
> Process swapper/0 (pid: 1, stack limit = 0x9f862240)
> Stack: (0x9f863d58 to 0x9f864000)
>
> In order to fix it, return an error when 'of_id' is NULL, which happens for the
> non-dt case.
>
> Also checked that audio is still functional when running the dt kernel for this
> board after applying this patch.
>
> Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
> ---
>  sound/soc/fsl/imx-audmux.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/sound/soc/fsl/imx-audmux.c b/sound/soc/fsl/imx-audmux.c
> index ab17381..2b29b48 100644
> --- a/sound/soc/fsl/imx-audmux.c
> +++ b/sound/soc/fsl/imx-audmux.c
> @@ -317,6 +317,9 @@ static int imx_audmux_probe(struct platform_device *pdev)
>         const struct of_device_id *of_id =
>                         of_match_device(imx_audmux_dt_ids, &pdev->dev);
>
> +       if (!of_id)
> +               return -EINVAL;

Hmm, this will break all non-dt users such as mx31/mx27.

I will send a proper patch for this.

Please discard this one.