linux-kernel - Re: [PATCH 1/2] bus: mhi: core: Fix parsing of mhi

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Date:   Thu, 16 Apr 2020 12:01:30 -0700
From:   Hemant Kumar <hemantk@...eaurora.org>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        "jhugo@...eaurora.org; dan.carpenter"@oracle.com
Cc:     linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        smohanad@...eaurora.org, dan.carpenter@...cle.com
Subject: Re: [PATCH 1/2] bus: mhi: core: Fix parsing of mhi_flags

Hi Mani,

On 4/13/20 5:07 AM, Manivannan Sadhasivam wrote:
> With the current parsing of mhi_flags, the following statement always
> return false:
>
> eob = !!(flags & MHI_EOB);
>
> This is due to the fact that 'enum mhi_flags' starts with index 0 and we
> are using direct AND operation to extract each bit. Fix this by using
> BIT() macro to extract each bit and make the mhi_flags index start from 1.
>
> Fixes: 189ff97cca53 ("bus: mhi: core: Add support for data transfer")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>   drivers/bus/mhi/core/main.c | 6 +++---
>   include/linux/mhi.h         | 2 +-
>   2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index eb4256b81406..4165a853c189 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -1090,9 +1090,9 @@ int mhi_gen_tre(struct mhi_controller *mhi_cntrl, struct mhi_chan *mhi_chan,
>   	if (ret)
>   		return ret;
>   
> -	eob = !!(flags & MHI_EOB);
> -	eot = !!(flags & MHI_EOT);
> -	chain = !!(flags & MHI_CHAIN);
> +	eob = !!(flags & BIT(0));
> +	eot = !!(flags & BIT(1));
> +	chain = !!(flags & BIT(2));

How about setting enums  with BIT macro and still use same enums above. 
If flags is having MHI _CHAIN (enum value 3) but comparing with BIT(2) 
(value 4) will not work.

>   	bei = !!(mhi_chan->intmod);
>   
>   	mhi_tre = tre_ring->wp;
> diff --git a/include/linux/mhi.h b/include/linux/mhi.h
> index ad1996001965..22185fecbbf2 100644
> --- a/include/linux/mhi.h
> +++ b/include/linux/mhi.h
> @@ -53,7 +53,7 @@ enum mhi_callback {
>    * @MHI_CHAIN: Linked transfer
>    */
>   enum mhi_flags {
> -	MHI_EOB,
> +	MHI_EOB = 1,
>   	MHI_EOT,
>   	MHI_CHAIN,
>   };

enum mhi_flags {

     MHI_EOB = BIT(0),

     MHI_EOT = BIT(1),

     MHI_CHAIN = BIT(2),

}

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