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Date:   Tue, 4 Apr 2023 16:35:13 +0100
From:   Jonathan Cameron <Jonathan.Cameron@huawei.com>
To:     Vladimir Oltean <vladimir.oltean@nxp.com>
CC:     Arnd Bergmann <arnd@arndb.de>, <linux-arch@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/2] asm-generic/io.h: suppress endianness warnings for
 readq() and writeq()
Message-ID: <20230404163513.00003b9f@huawei.com>
In-Reply-To: <20230109131153.991322-1-vladimir.oltean@nxp.com>
References: <20230109131153.991322-1-vladimir.oltean@nxp.com>
Organization: Huawei Technologies R&D (UK) Ltd.
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On Mon,  9 Jan 2023 15:11:52 +0200
Vladimir Oltean <vladimir.oltean@nxp.com> wrote:

> Commit c1d55d50139b ("asm-generic/io.h: Fix sparse warnings on
> big-endian architectures") missed fixing the 64-bit accessors.
> 
> Arnd explains in the attached link why the casts are necessary, even if
> __raw_readq() and __raw_writeq() do not take endian-specific types.
> 
> Link: https://lore.kernel.org/lkml/9105d6fc-880b-4734-857d-e3d30b87ccf6@app.fastmail.com/
> Suggested-by: Arnd Bergmann <arnd@arndb.de>
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Found this when about to send an equivalent patch. Not seeing this in linux-next yet
and would be good to clean the resulting warnings up.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  include/asm-generic/io.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/asm-generic/io.h b/include/asm-generic/io.h
> index 4c44a29b5e8e..d78c3056c98f 100644
> --- a/include/asm-generic/io.h
> +++ b/include/asm-generic/io.h
> @@ -236,7 +236,7 @@ static inline u64 readq(const volatile void __iomem *addr)
>  
>  	log_read_mmio(64, addr, _THIS_IP_, _RET_IP_);
>  	__io_br();
> -	val = __le64_to_cpu(__raw_readq(addr));
> +	val = __le64_to_cpu((__le64 __force)__raw_readq(addr));
>  	__io_ar(val);
>  	log_post_read_mmio(val, 64, addr, _THIS_IP_, _RET_IP_);
>  	return val;
> @@ -287,7 +287,7 @@ static inline void writeq(u64 value, volatile void __iomem *addr)
>  {
>  	log_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
>  	__io_bw();
> -	__raw_writeq(__cpu_to_le64(value), addr);
> +	__raw_writeq((u64 __force)__cpu_to_le64(value), addr);
>  	__io_aw();
>  	log_post_write_mmio(value, 64, addr, _THIS_IP_, _RET_IP_);
>  }