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[73.185.129.58]) by smtp.googlemail.com with ESMTPSA id t11sm13670938qkp.82.2022.02.16.05.41.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 16 Feb 2022 05:41:58 -0800 (PST) Message-ID: <8481b845-31c2-a830-4fe1-27798618fc2e@linaro.org> Date: Wed, 16 Feb 2022 07:41:56 -0600 Precedence: bulk X-Mailing-List: mhi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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 Cc: mhi@lists.linux.dev, 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 , Hemant Kumar , stable@vger.kernel.org References: <20220212182117.49438-1-manivannan.sadhasivam@linaro.org> <20220212182117.49438-2-manivannan.sadhasivam@linaro.org> <0c95c9a5-cf66-dcec-bfde-0ca201206c8b@linaro.org> <20220216113353.GB6225@workstation> From: Alex Elder In-Reply-To: <20220216113353.GB6225@workstation> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 >>> >>> 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. >> > > 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]; >>