On 02/23/2018 05:47 PM, Shawn Lin wrote:
> cat /sys/kernel/debug/mmc0/regs will hang up the system since
> it's in runtime suspended state, so the genpd and biu_clk is
> off. This patch fixes this problem by calling pm_runtime_get_sync
> to wake it up before reading the registers.
>
> Fixes: e9ed8835e990 ("mmc: dw_mmc: add runtime PM callback")
> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Shawn Lin <shawn.lin@xxxxxxxxxxxxxx>
Reviewed-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>
Best Regards,
Jaehoon Chung
> ---
>
> drivers/mmc/host/dw_mmc.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
> index 0aa3997..e38dcf4 100644
> --- a/drivers/mmc/host/dw_mmc.c
> +++ b/drivers/mmc/host/dw_mmc.c
> @@ -165,6 +165,8 @@ static int dw_mci_regs_show(struct seq_file *s, void *v)
> {
> struct dw_mci *host = s->private;
>
> + pm_runtime_get_sync(host->dev);
> +
> seq_printf(s, "STATUS:\t0x%08x\n", mci_readl(host, STATUS));
> seq_printf(s, "RINTSTS:\t0x%08x\n", mci_readl(host, RINTSTS));
> seq_printf(s, "CMD:\t0x%08x\n", mci_readl(host, CMD));
> @@ -172,6 +174,8 @@ static int dw_mci_regs_show(struct seq_file *s, void *v)
> seq_printf(s, "INTMASK:\t0x%08x\n", mci_readl(host, INTMASK));
> seq_printf(s, "CLKENA:\t0x%08x\n", mci_readl(host, CLKENA));
>
> + pm_runtime_put_autosuspend(host->dev);
> +
> return 0;
> }
>
>