From: Geert Uytterhoeven geert+renesas@glider.be
commit 30332eeefec8f83afcea00c360f99ef64b87f220 upstream.
Hardware registers of devices under control of power management cannot be accessed at all times. If such a device is suspended, register accesses may lead to undefined behavior, like reading bogus values, or causing exceptions or system lock-ups.
Extend struct debugfs_regset32 with an optional field to let device drivers specify the device the registers in the set belong to. This allows debugfs_show_regset32() to make sure the device is resumed while its registers are being read.
Signed-off-by: Geert Uytterhoeven geert+renesas@glider.be Reviewed-by: Niklas Söderlund niklas.soderlund@ragnatech.se Reviewed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Acked-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Herbert Xu herbert@gondor.apana.org.au Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/debugfs/file.c | 8 ++++++++ include/linux/debugfs.h | 1 + 2 files changed, 9 insertions(+)
--- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -18,6 +18,7 @@ #include <linux/slab.h> #include <linux/atomic.h> #include <linux/device.h> +#include <linux/pm_runtime.h> #include <linux/poll.h>
#include "internal.h" @@ -1084,7 +1085,14 @@ static int debugfs_show_regset32(struct { struct debugfs_regset32 *regset = s->private;
+ if (regset->dev) + pm_runtime_get_sync(regset->dev); + debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, ""); + + if (regset->dev) + pm_runtime_put(regset->dev); + return 0; }
--- a/include/linux/debugfs.h +++ b/include/linux/debugfs.h @@ -35,6 +35,7 @@ struct debugfs_regset32 { const struct debugfs_reg32 *regs; int nregs; void __iomem *base; + struct device *dev; /* Optional device for Runtime PM */ };
extern struct dentry *arch_debugfs_dir;