On 2/12/22 12:20 PM, Manivannan Sadhasivam wrote:
From: Paul Davey <paul.davey@xxxxxxxxxxxxxxxxxxx>
On big endian architectures the mhi debugfs files which report pm state
give "Invalid State" for all states. This is caused by using
find_last_bit which takes an unsigned long* while the state is passed in
as an enum mhi_pm_state which will be of int size.
I think this would have fixed it too, but your fix is better.
int index = find_last_bit(&(unsigned long)state, 32);
Fix by using __fls to pass the value of state instead of find_last_bit.
Fixes: a6e2e3522f29 ("bus: mhi: core: Add support for PM state transitions")
Signed-off-by: Paul Davey <paul.davey@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Manivannan Sadhasivam <mani@xxxxxxxxxx>
Reviewed-by: Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
---
drivers/bus/mhi/core/init.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index 046f407dc5d6..af484b03558a 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -79,10 +79,12 @@ static const char * const mhi_pm_state_str[] = {
const char *to_mhi_pm_state_str(enum mhi_pm_state state)
The mhi_pm_state enumerated type is an enumerated sequence, not
a bit mask. So knowing what the last (most significant) set bit
is not meaningful. Or normally it shouldn't be.
If mhi_pm_state really were a bit mask, then its values should
be defined that way, i.e.,
MHI_PM_STATE_DISABLE = 1 << 0,
MHI_PM_STATE_DISABLE = 1 << 1,
. . .
What's really going on is that the state value passed here
*is* a bitmask, whose bit positions are those mhi_pm_state
values. So the state argument should have type u32.
This is a *separate* bug/issue. It could be fixed separately
(before this patch), but I'd be OK with just explaining why
this change would occur as part of this modified patch.
{
- unsigned long pm_state = state;
- int index = find_last_bit(&pm_state, 32);
+ int index;
- if (index >= ARRAY_SIZE(mhi_pm_state_str))
+ if (state)
+ index = __fls(state);
+
+ if (!state || index >= ARRAY_SIZE(mhi_pm_state_str))
return "Invalid State";
Do this test and return first, and skip the additional
check for "if (state)".
-Alex
return mhi_pm_state_str[index];
