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Date:   Mon, 28 Feb 2022 09:30:26 -0600
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Subject: Re: [PATCH v4 01/27] bus: mhi: Fix pm_state conversion to string
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To:     Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>,
        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 <paul.davey@alliedtelesis.co.nz>,
        Manivannan Sadhasivam <mani@kernel.org>,
        Hemant Kumar <hemantk@codeaurora.org>, stable@vger.kernel.org
References: <20220228124344.77359-1-manivannan.sadhasivam@linaro.org>
 <20220228124344.77359-2-manivannan.sadhasivam@linaro.org>
From:   Alex Elder <elder@linaro.org>
In-Reply-To: <20220228124344.77359-2-manivannan.sadhasivam@linaro.org>
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On 2/28/22 6:43 AM, 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.
> 
> 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.

(Grumble grumble too much static data in header file.)

Reviewed-by: Alex Elder <elder@linaro.org>

> 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
> [mani: changed the function argument to u32]
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
>   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 046f407dc5d6..09394a1c29ec 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 e2e10474a9d9..3508cbbf555d 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);