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Subject[PATCH 5.15 111/230] bus: mhi: Fix pm_state conversion to string
From: Paul Davey <>

[ Upstream commit 64f93a9a27c1970fa8ee5ffc5a6ae2bda477ec5b ]

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.

Fix by using __fls to pass the value of state instead of find_last_bit.

Also the current API expects "mhi_pm_state" enumerator as the function
argument but the function only works with bitmasks. So as Alex suggested,
let's change the argument to u32 to avoid confusion.

Fixes: a6e2e3522f29 ("bus: mhi: core: Add support for PM state transitions")
[mani: changed the function argument to u32]
Reviewed-by: Manivannan Sadhasivam <>
Reviewed-by: Hemant Kumar <>
Reviewed-by: Alex Elder <>
Signed-off-by: Paul Davey <>
Signed-off-by: Manivannan Sadhasivam <>
Signed-off-by: Greg Kroah-Hartman <>
Signed-off-by: Sasha Levin <>
drivers/bus/mhi/core/init.c | 10 ++++++----
drivers/bus/mhi/core/internal.h | 2 +-
2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index c0187367ae75..d8787aaa176b 100644
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -77,12 +77,14 @@ static const char * const mhi_pm_state_str[] = {
[MHI_PM_STATE_LD_ERR_FATAL_DETECT] = "Linkdown or Error Fatal Detect",

-const char *to_mhi_pm_state_str(enum mhi_pm_state state)
+const char *to_mhi_pm_state_str(u32 state)
- 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";

return mhi_pm_state_str[index];
diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index c02c4d48b744..71f181402be9 100644
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -622,7 +622,7 @@ void mhi_free_bhie_table(struct mhi_controller *mhi_cntrl,
enum mhi_pm_state __must_check mhi_tryset_pm_state(
struct mhi_controller *mhi_cntrl,
enum mhi_pm_state state);
-const char *to_mhi_pm_state_str(enum mhi_pm_state state);
+const char *to_mhi_pm_state_str(u32 state);
int mhi_queue_state_transition(struct mhi_controller *mhi_cntrl,
enum dev_st_transition state);
void mhi_pm_st_worker(struct work_struct *work);

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