| Message ID | 20220212182117.49438-2-manivannan.sadhasivam@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | Add initial support for MHI endpoint stack | expand |
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];
On Tue, Feb 15, 2022 at 02:01:54PM -0600, Alex Elder wrote: > 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. > I agree with you. It should be 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. > It makes sense to do it in the same patch itself as the change is minimal and moreover this patch will also get backported to stable. > > { > > - 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)". > We need to calculate index for the second check, so I guess the current code is fine. Thanks, Mani > -Alex > > > return mhi_pm_state_str[index]; >
On 2/16/22 5:33 AM, Manivannan Sadhasivam wrote: > On Tue, Feb 15, 2022 at 02:01:54PM -0600, Alex Elder wrote: >> 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. >> > > I agree with you. It should be 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. >> > > It makes sense to do it in the same patch itself as the change is > minimal and moreover this patch will also get backported to stable. Sounds good to me. -Alex >>> { >>> - 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)". >> > > We need to calculate index for the second check, so I guess the current > code is fine. > > Thanks, > Mani > >> -Alex >> >>> return mhi_pm_state_str[index]; >>
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) { - 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];