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[73.185.129.58]) by smtp.googlemail.com with ESMTPSA id p11sm25923177iov.38.2022.02.15.12.01.54 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Feb 2022 12:01:55 -0800 (PST) Message-ID: <0c95c9a5-cf66-dcec-bfde-0ca201206c8b@linaro.org> Date: Tue, 15 Feb 2022 14:01:54 -0600 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v3 01/25] bus: mhi: Fix pm_state conversion to string Content-Language: en-US To: Manivannan Sadhasivam , mhi@lists.linux.dev Cc: quic_hemantk@quicinc.com, quic_bbhatt@quicinc.com, quic_jhugo@quicinc.com, vinod.koul@linaro.org, bjorn.andersson@linaro.org, dmitry.baryshkov@linaro.org, quic_vbadigan@quicinc.com, quic_cang@quicinc.com, quic_skananth@quicinc.com, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Davey , Manivannan Sadhasivam , Hemant Kumar , stable@vger.kernel.org References: <20220212182117.49438-1-manivannan.sadhasivam@linaro.org> <20220212182117.49438-2-manivannan.sadhasivam@linaro.org> From: Alex Elder In-Reply-To: <20220212182117.49438-2-manivannan.sadhasivam@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/12/22 12:20 PM, Manivannan Sadhasivam wrote: > From: Paul Davey > > 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 > Reviewed-by: Manivannan Sadhasivam > Reviewed-by: Hemant Kumar > Cc: stable@vger.kernel.org > Signed-off-by: Manivannan Sadhasivam > --- > 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];