On 2/12/22 12:20 PM, Manivannan Sadhasivam wrote:
From: Paul Davey paul.davey@alliedtelesis.co.nz
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@alliedtelesis.co.nz Reviewed-by: Manivannan Sadhasivam mani@kernel.org Reviewed-by: Hemant Kumar hemantk@codeaurora.org Cc: stable@vger.kernel.org Signed-off-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
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];